Document and Entity Information (USD $) In Billions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Feb. 20, 2013	Jun. 30, 2012
Document and Entity Information
Entity Registrant Name	Transocean Ltd.
Entity Central Index Key	0001451505
Document Type	10-K
Document Period End Date	Dec. 31, 2012
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Public Float			$ 16.1
Entity Common Stock, Shares Outstanding		359,542,668
Document Fiscal Year Focus	2012
Document Fiscal Period Focus	FY

CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating revenues
Contract drilling revenues	$ 8,773	$ 7,407	$ 7,698
Other revenues	423	620	251
Total operating revenues	9,196	8,027	7,949
Costs and expenses
Operating and maintenance	6,106	6,179	4,219
Depreciation and amortization	1,123	1,109	1,009
General and administrative	282	288	246
Total costs and expenses	7,511	7,576	5,474
Loss on impairment	(140)	(5,201)
Gain (loss) on disposal of assets, net	36	(12)	255
Operating income (loss)	1,581	(4,762)	2,730
Other income (expense), net
Interest income	56	44	23
Interest expense, net of amounts capitalized	(723)	(621)	(567)
Gain (loss) on retirement of debt	2		(33)
Other, net	(50)	(99)	2
Total other income (expense), net	(715)	(676)	(575)
Income (loss) from continuing operations before income tax expense	866	(5,438)	2,155
Income tax expense	50	324	292
Income (loss) from continuing operations	816	(5,762)	1,863
Income (loss) from discontinued operations, net of tax	(1,027)	85	(894)
Net income (loss)	(211)	(5,677)	969
Net income attributable to noncontrolling interest	8	77	43
Net income (loss) attributable to controlling interest	$ (219)	$ (5,754)	$ 926
Earnings (loss) per share-basic
Earnings (loss) from continuing operations (in dollars per share)	$ 2.27	$ (18.14)	$ 5.66
Earnings (loss) from discontinued operations (in dollars per share)	$ (2.89)	$ 0.26	$ (2.78)
Earnings (loss) per share (in dollars per share)	$ (0.62)	$ (17.88)	$ 2.88
Earnings (loss) per share-diluted
Earnings (loss) from continuing operations (in dollars per share)	$ 2.27	$ (18.14)	$ 5.66
Earnings (loss) from discontinued operations (in dollars per share)	$ (2.89)	$ 0.26	$ (2.78)
Earnings (loss) per share (in dollars per share)	$ (0.62)	$ (17.88)	$ 2.88
Weighted-average shares outstanding
Basic (in shares)	356	322	320
Diluted (in shares)	356	322	320

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)
Net income (loss)	$ (211)	$ (5,677)	$ 969
Other comprehensive income (loss) before income taxes
Unrecognized components of net periodic benefit costs	(52)	(204)	(8)
Unrecognized gain (loss) on derivative instruments	3	(13)	(29)
Unrecognized loss on marketable securities		(13)
Recognized components of net periodic benefit costs	47	25	16
Recognized (gain) loss on derivative instruments	(1)	11	12
Recognized loss on marketable securities	2	13
Other comprehensive income (loss) before income taxes	(1)	(181)	(9)
Income taxes related to other comprehensive income (loss)	(7)	13	(9)
Other comprehensive income (loss), net of income taxes	(8)	(168)	(18)
Total comprehensive income (loss)	(219)	(5,845)	951
Total comprehensive income attributable to noncontrolling interest	8	73	22
Total comprehensive income (loss) attributable to controlling interest	$ (227)	$ (5,918)	$ 929

CONSOLIDATED BALANCE SHEETS (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Assets
Cash and cash equivalents	$ 5,134	$ 4,017	$ 3,354	$ 1,130
Accounts receivable, net
Trade	1,940	2,049	1,653
Other	260	127	190
Materials and supplies, net	610	529	425
Assets held for sale	179	26
Deferred income taxes, net	142	142	115
Other current assets	382	646	472
Total current assets	8,647	7,536	6,209
Property and equipment	26,967	24,833	22,149
Property and equipment of consolidated variable interest entities	1,092	2,252	2,214
Less accumulated depreciation	7,179	6,297	5,244
Property and equipment, net	20,880	20,788	19,119
Goodwill	2,987	3,217	8,132
Other assets	1,741	3,491	3,354
Total assets	34,255	35,032	36,814
Liabilities and equity
Accounts payable	1,047	880	832
Accrued income taxes	116	86	109
Debt due within one year	1,339	1,942	1,917
Debt of consolidated variable interest entities due within one year	28	245	243
Other current liabilities	2,933	2,375	895
Total current liabilities	5,463	5,528	3,996
Long-term debt	10,929	10,756	8,354
Long-term debt of consolidated variable interest entities	163	593	707
Deferred income taxes, net	366	487	585
Other long-term liabilities	1,604	1,925	1,791
Total long-term liabilities	13,062	13,761	11,437
Commitments and contingencies
Redeemable noncontrolling interest		116	41
Shares, CHF 15.00 par value, 402,282,355 authorized, 167,617,649 conditionally authorized at December 31, 2012 and 2011, 373,830,649 and 365,135,298 issued at December 31, 2012 and 2011, respectively; and 359,505,251 and 349,805,793 outstanding at December 31, 2012 and 2011, respectively	5,130	4,982	4,482
Additional paid-in capital	7,521	7,211	7,504
Treasury shares, at cost, 2,863,267 held at December 31, 2012 and 2011	(240)	(240)	(240)
Retained earnings	3,855	4,180	9,934
Accumulated other comprehensive loss	(521)	(496)	(332)
Total controlling interest shareholders' equity	15,745	15,637	21,348
Noncontrolling interest	(15)	(10)	(8)
Total equity	15,730	15,627	21,340	20,559
Total liabilities and equity	$ 34,255	$ 35,032	$ 36,814

CONSOLIDATED BALANCE SHEETS (Parenthetical) In Millions, except Share data, unless otherwise specified	Dec. 31, 2012 USD ($)	Dec. 31, 2012 CHF	Dec. 31, 2011 USD ($)	Dec. 31, 2011 CHF
CONSOLIDATED BALANCE SHEETS
Shares, CHF par value (in Swiss francs per share)		15.00		15.00
Shares, authorized	402,282,355	402,282,355	402,282,355	402,282,355
Shares, conditionally authorized	167,617,649	167,617,649	167,617,649	167,617,649
Shares, issued	373,830,649	373,830,649	365,135,298	365,135,298
Shares, outstanding	359,505,251	359,505,251	349,805,793	349,805,793
Treasury shares	2,863,267	2,863,267	2,863,267	2,863,267
Accounts receivable, allowance for doubtful accounts (in dollars)	$ 20		$ 28

- Definition

Number of shares of common stock outstanding. Common stock represent the ownership interest in a corporation.

+ References+ Details

CONSOLIDATED STATEMENTS OF EQUITY In Millions, unless otherwise specified	Total USD ($)	Total CHF	Total controlling interest shareholders' equity USD ($)	Shares USD ($)	Additional paid-in capital USD ($)	Treasury shares, at cost USD ($)	Retained earnings USD ($)	Accumulated other comprehensive loss USD ($)	Noncontrolling interest USD ($)
Balance at Dec. 31, 2009	$ 20,559		$ 20,552	$ 4,472	$ 7,407		$ 9,008	$ (335)	$ 7
Balance (in shares) at Dec. 31, 2009				321
Increase (Decrease) in Shareholders' Equity
Share-based compensation	102		102		102
Issuance of shares under share-based compensation plans	(1)		(1)	10	(11)
Issuance of shares under share-based compensation plans (in shares)				1
Reclassification from redeemable noncontrolling interest									(26)
Purchases of shares held in treasury	(240)	(257)	(240)			(240)
Purchases of shares held in treasury (in shares)	(2.9)			(3.0)
Other, net	(16)		6		6				4
Net income (loss) attributable to controlling interest	926						926
Other comprehensive income (loss) attributable to controlling interest								3
Total comprehensive income (loss) attributable to controlling interest	929		929
Total comprehensive income attributable to noncontrolling interest	(22)								7
Total comprehensive income (loss)	951
Balance at Dec. 31, 2010	21,340		21,348	4,482	7,504	(240)	9,934	(332)	(8)
Balance (in shares) at Dec. 31, 2010				319
Increase (Decrease) in Shareholders' Equity
Share-based compensation	95		95		95
Issuance of shares in public offering, net of issue costs	1,159		1,159	488	671
Issuance of shares (in shares)				30.0
Issuance of shares under share-based compensation plans	(6)		(6)	12	(18)
Issuance of shares under share-based compensation plans (in shares)				1
Obligation for distribution of qualifying additional paid-in capital	(1,041)		(1,041)		(1,041)
Net income (loss) attributable to controlling interest	(5,754)						(5,754)
Other comprehensive income (loss) attributable to controlling interest								(164)
Total comprehensive income (loss) attributable to controlling interest	(5,918)		(5,918)
Total comprehensive income attributable to noncontrolling interest	(73)								(2)
Total comprehensive income (loss)	(5,845)
Balance at Dec. 31, 2011	15,627		15,637	4,982	7,211	(240)	4,180	(496)	(10)
Balance (in shares) at Dec. 31, 2011				350
Increase (Decrease) in Shareholders' Equity
Share-based compensation	97		97		97
Issuance of shares under share-based compensation plans	(3)		(3)	14	(17)
Issuance of shares under share-based compensation plans (in shares)				1
Issuance of shares in exchange for redeemable noncontrolling interest	367		367	134	233
Issuance of shares in exchange for redeemable noncontrolling interest (in shares)				9.0
Fair value adjustment of redeemable noncontrolling interest	(106)		(106)				(106)
Reclassification from redeemable noncontrolling interest	(17)		(17)					(17)
Other, net	(3)		(3)		(3)
Net income (loss) attributable to controlling interest	(219)						(219)
Other comprehensive income (loss) attributable to controlling interest								(8)
Total comprehensive income (loss) attributable to controlling interest	(227)		(227)
Total comprehensive income attributable to noncontrolling interest	(8)								(5)
Total comprehensive income (loss)	(219)
Balance at Dec. 31, 2012	$ 15,730		$ 15,745	$ 5,130	$ 7,521	$ (240)	$ 3,855	$ (521)	$ (15)
Balance (in shares) at Dec. 31, 2012				360

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Cash flows from operating activities
Net income (loss)	$ (211)	$ (5,677)	$ 969
Adjustments to reconcile to net cash provided by operating activities:
Amortization of drilling contract intangibles	(42)	(45)	(98)
Depreciation and amortization	1,123	1,109	1,009
Depreciation and amortization of assets in discontinued operations	183	342	580
Share-based compensation expense	97	95	102
Loss on impairment	140	5,201
Loss on impairment of assets in discontinued operations	986	38	1,012
(Gain) loss on disposal of assets, net	(36)	12	(255)
Gain on disposal of assets in discontinued operations, net	(82)	(183)	(2)
Amortization of debt issue costs, discounts and premiums, net	68	125	189
Deferred income taxes	(133)	(62)	(104)
Other, net	72	144	(1)
Changes in deferred revenue, net	(54)	(16)	205
Changes in deferred expenses, net	85	(61)	(79)
Changes in operating assets and liabilities	512	803	379
Net cash provided by operating activities	2,708	1,825	3,906
Cash flows from investing activities
Capital expenditures	(1,303)	(974)	(1,349)
Capital expenditures for discontinued operations	(106)	(46)	(42)
Investment in business combination, net of cash acquired		(1,246)
Payment for settlement of forward exchange contract, net		(78)
Proceeds from disposal of assets, net	191	14	60
Proceeds from disposal of assets in discontinued operations, net	789	447
Proceeds from insurance recoveries for loss of drilling unit			560
Proceeds from sale of marketable securities			37
Other, net	40	(13)	13
Net cash used in investing activities	(389)	(1,896)	(721)
Cash flows from financing activities
Changes in short-term borrowings, net	(260)	(88)	(193)
Proceeds from debt	1,493	2,939	2,054
Repayments of debt	(2,282)	(2,409)	(2,565)
Proceeds from restricted cash investments	311	479
Deposits to restricted cash investments	(167)	(523)
Proceeds from share issuance		1,211
Distribution of qualifying additional paid-in capital	(278)	(763)
Purchases of shares held in treasury			(240)
Financing costs	(24)	(83)	(15)
Other, net	5	(29)	(2)
Net cash provided by (used in) financing activities	(1,202)	734	(961)
Net increase in cash and cash equivalents	1,117	663	2,224
Cash and cash equivalents at beginning of period	4,017	3,354	1,130
Cash and cash equivalents at end of period	$ 5,134	$ 4,017	$ 3,354

Nature of Business	12 Months Ended
Nature of Business	Dec. 31, 2012
Nature of Business
Nature of Business	Note 1—Nature of Business Transocean Ltd. (together with its subsidiaries and predecessors, unless the context requires otherwise, “Transocean,” the “Company,” “we,” “us” or “our”) is a leading international provider of offshore contract drilling services for oil and gas wells. We specialize in technically demanding sectors of the offshore drilling business with a particular focus on deepwater and harsh environment drilling services. Our mobile offshore drilling fleet is considered one of the most versatile fleets in the world. We contract our drilling rigs, related equipment and work crews predominantly on a dayrate basis to drill oil and gas wells. At December 31, 2012, we owned or had partial ownership interests in and operated 82 mobile offshore drilling units associated with our continuing operations. As of this date, our fleet consisted of 48 High-Specification Floaters (Ultra-Deepwater, Deepwater and Harsh Environment semisubmersibles and drillships), 25 Midwater Floaters, and nine High-Specification Jackups. We also had six Ultra-Deepwater drillships and three High-Specification Jackups under construction or under contract to be constructed. See Note 12—Drilling Fleet. We also provide oil and gas drilling management services, drilling engineering and drilling project management services through Applied Drilling Technology Inc., our wholly owned subsidiary, and through ADT International, a division of one of our United Kingdom (“U.K.”) subsidiaries (together, “ADTI”). ADTI conducts drilling management services primarily either on a dayrate or on a completed-project, fixed-price or turnkey basis. In November 2012, in connection with our plan to discontinue operations associated with the Standard Jackup and swamp barge asset groups, we completed the sale of 37 Standard Jackups and one swamp barge to Shelf Drilling Holdings, Ltd. (“Shelf Drilling”). For a transition period following the completion of the sale transactions, we agreed to continue to operate a substantial portion of the Standard Jackups on behalf of Shelf Drilling and to provide certain other transition services to Shelf Drilling. Under operating agreements, we agreed to continue to operate these Standard Jackups on behalf of Shelf Drilling for periods ranging from nine months to 27 months, until expiration or novation of the underlying drilling contracts by Shelf Drilling. Under a transition services agreement, we agreed to provide certain transition services for a period of up to 18 months following the completion of the sale transactions. As of December 31, 2012, we operated 25 Standard Jackups under operating agreements with Shelf Drilling. See Note 9—Discontinued Operations. In March 2012, we announced our intent to discontinue drilling management operations in the shallow waters of the U.S. Gulf of Mexico, upon completion of our then existing contracts. In December 2012, we completed the final project of our drilling management services operations in the U.S. Gulf of Mexico and discontinued offering our drilling management services in this region. See Note 9—Discontinued Operations. In March 2011, we engaged an unaffiliated advisor to coordinate the sale of the assets of our oil and gas properties operating segment, which comprised the exploration, development and production activities performed by Challenger Minerals Inc., Challenger Minerals (North Sea) Limited and Challenger Minerals (Ghana) Limited (collectively, “CMI”). In October 2011, we completed the sale of Challenger Minerals (North Sea) Limited, in April 2012, we completed the sale of the assets of Challenger Minerals Inc. and in December 2012, we completed the sale of the assets of Challenger Minerals (Ghana) Limited. See Note 9—Discontinued Operations.

Significant Accounting Policies	12 Months Ended
Significant Accounting Policies	Dec. 31, 2012
Significant Accounting Policies
Significant Accounting Policies	Note 2—Significant Accounting Policies Accounting estimates—To prepare financial statements in accordance with accounting principles generally accepted in the U.S., we are required to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosures of contingent assets and liabilities. On an ongoing basis, we evaluate our estimates and assumptions, including those related to our discontinued operations, allowance for doubtful accounts, materials and supplies obsolescence, property and equipment, investments, notes receivable, goodwill and other intangible assets, income taxes, contingencies, share-based compensation, defined benefit pension plans and other postretirement benefits. We base our estimates and assumptions on historical experience and on various other factors we believe are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying amounts of assets and liabilities that are not readily apparent from other sources. Actual results could differ from such estimates. Fair value measurements—We estimate fair value at a price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants in the principal market for the asset or liability. Our valuation techniques require inputs that we categorize using a three-level hierarchy, from highest to lowest level of observable inputs, as follows: (1) significant observable inputs, including unadjusted quoted prices for identical assets or liabilities in active markets (“Level 1”), (2) significant other observable inputs, including direct or indirect market data for similar assets or liabilities in active markets or identical assets or liabilities in less active markets (“Level 2”) and (3) significant unobservable inputs, including those that require considerable judgment for which there is little or no market data (“Level 3”). When multiple input levels are required for a valuation, we categorize the entire fair value measurement according to the lowest level of input that is significant to the measurement even though we may have also utilized significant inputs that are more readily observable. Consolidation—We consolidate entities in which we have a majority voting interest and entities that meet the criteria for variable interest entities for which we are deemed to be the primary beneficiary for accounting purposes. We eliminate intercompany transactions and accounts in consolidation. We apply the equity method of accounting for an investment in an entity if we have the ability to exercise significant influence over the entity that (a) does not meet the variable interest entity criteria or (b) meets the variable interest entity criteria, but for which we are not deemed to be the primary beneficiary. We apply the cost method of accounting for an investment in an entity if we do not have the ability to exercise significant influence over the unconsolidated entity. See Note 6—Variable Interest Entities. In the year ended December 31, 2012, we did not have interests in any unconsolidated entities for which we earned equity in earnings. In the years ended December 31, 2011 and 2010, we recognized equity in earnings of unconsolidated entities in the amount of $5 million and $8 million, respectively. At December 31, 2012 and 2011, our investments in and advances to unconsolidated affiliates had carrying amounts of less than $1 million. Business combination—In connection with our acquisition of Aker Drilling ASA (“Aker Drilling), we applied the acquisition method of accounting. Accordingly, we recorded the acquired assets and assumed liabilities at fair value and recognized goodwill to the extent the fair value of the business acquired exceeded the fair value of the net assets. We estimated the fair values of the acquired assets and assumed liabilities as of the date of the acquisition. See Note 5—Business Combination. Discontinued operations—We present as discontinued operations the operating results of a component of our business that either has been disposed of or is classified as held for sale when both of the following conditions are met: (a) the operations and cash flows of the component have been or will be eliminated from our ongoing operations as a result of the disposal transaction and (b) we will not have any significant continuing involvement in the operations of the disposed component. For discontinued operations that are disposed of other than by sale, we present the operating results as discontinued in the period in which the disposal group is either abandoned, distributed or exchanged, depending on the manner of disposal. We consider a component of our business to be one that comprises operations and cash flows that can be clearly distinguished, operationally and for financial reporting purposes, from the rest of our business. During the year ended December 31, 2012, we reclassified to discontinued operations the operating results, assets and liabilities associated with the operations of our Standard Jackup and swamp barge asset groups, components of our contract drilling services segment, and the operations of our U.S. Gulf of Mexico drilling management services, a component of our drilling management services segment. During the year ended December 31, 2011, we reclassified to discontinued operations the operating results, assets and liabilities associated with the operations of our Caspian Sea contract drilling operations, a component of our contract drilling services segment, and the operations of our oil and gas properties segment. See Note 9—Discontinued Operations. Operating revenues and expenses—We recognize operating revenues as they are earned, based on contractual dayrates or on a fixed-price basis. In connection with drilling contracts, we may receive revenues for preparation and mobilization of equipment and personnel or for capital improvements to rigs. In connection with new drilling contracts, revenues earned and incremental costs incurred directly related to contract preparation and mobilization are deferred and recognized over the primary contract term of the drilling project using the straight-line method. Our policy to amortize the fees related to contract preparation, mobilization and capital upgrades on a straight-line basis over the estimated firm period of drilling is consistent with the general pace of activity, level of services being provided and dayrates being earned over the life of the contract. For contractual daily rate contracts, we account for loss contracts as the losses are incurred. Costs of relocating drilling units without contracts to more promising market areas are expensed as incurred. Upon completion of drilling contracts, any demobilization fees received are reported in income, as are any related expenses. Capital upgrade revenues received are deferred and recognized over the primary contract term of the drilling project. The actual cost incurred for the capital upgrade is depreciated over the estimated useful life of the asset. We incur periodic survey and drydock costs in connection with obtaining regulatory certification to operate our rigs and well control systems on an ongoing basis. Costs associated with these certifications are deferred and amortized on a straight-line basis over the period until the next survey. Included in our contract drilling revenues, we recognize amortization associated with our drilling contract intangible assets and liabilities. In connection with our business combination with GlobalSantaFe Corporation in November 2007, we recognized drilling contract intangible assets and liabilities for acquired drilling contracts for future contract drilling services. The terms of the acquired contracts include fixed dayrates that were above or below the market dayrates that were available for similar contracts as of the date of the business combination. We recognized the fair value adjustments as contract intangible assets and liabilities, recorded in other assets and other long-term liabilities, respectively. We amortize the resulting contract drilling intangible revenues on a straight-line basis over the respective contract period and include such revenues in contract drilling revenues on our consolidated statements of operations. In the years ended December 31, 2012, 2011 and 2010, we recognized contract drilling intangible revenues of $42 million, $45 million and $98 million, respectively. See Note 13—Goodwill and Other Intangible Assets. Other revenues—Our other revenues represent those derived from drilling management services and customer reimbursable revenues. For fixed-price contracts associated with our drilling management services, we recognize revenues and expenses upon well completion and customer acceptance, and we recognize loss provisions on contracts in progress when losses are probable. We consider customer reimbursable revenues to be billings to our customers for reimbursement of certain equipment, materials and supplies, third-party services, employee bonuses and other expenses that we recognize in operating and maintenance expense, the result of which has little or no effect on operating income. Share-based compensation—For time-based awards, we recognize compensation expense on a straight-line basis through the date the employee is no longer required to provide service to earn the award (the “service period”). For market-based awards that vest at the end of the service period, we recognize compensation expense on a straight-line basis through the end of the service period. For performance-based awards with graded vesting conditions, we recognize compensation expense on a straight-line basis over the service period for each separately vesting portion of the award as if the award was, in substance, multiple awards. We recognize share-based compensation expense net of a forfeiture rate that we estimate at the time of grant based on historical experience and future expectations, and we adjust the estimated forfeiture rate, if necessary, in subsequent periods based on actual forfeitures or changed expectations. To measure the fair values of time-based restricted shares and deferred units granted or modified, we use the market price of our shares on the grant date or modification date. To measure the fair values of stock options and stock appreciation rights granted or modified, we use the Black-Scholes-Merton option-pricing model and apply assumptions for the expected life, risk-free interest rate, dividend yield and expected volatility. The expected life is based on historical information of past employee behavior regarding exercises and forfeitures of options. The risk-free interest rate is based upon the published U.S. Treasury yield curve in effect at the time of grant or modification for instruments with a similar life. The dividend yield is based on our history and expectation of dividend payouts. The expected volatility is based on a blended rate with an equal weighting of the (a) historical volatility based on historical data for an amount of time approximately equal to the expected life and (b) implied volatility derived from our at-the-money, long-dated call options. To measure the fair values of market-based deferred units granted or modified, we use a Monte Carlo simulation model and, in addition to the assumptions applied for the Black-Scholes-Merton option-pricing model, we apply assumptions using a risk neutral approach and an average price at the performance start date. The risk neutral approach assumes that all peer group stocks grow at the risk-free rate. The average price at the performance start date is based on the average stock price for the preceding 30 trading days. We recognize share-based compensation expense in the same financial statement line item as cash compensation paid to the respective employees. Tax deduction benefits for awards in excess of recognized compensation costs are reported as a financing cash flow. In the years ended December 31, 2012, 2011 and 2010, share-based compensation expense was $97 million, $95 million and $102 million, respectively. In the years ended December 31, 2012, 2011 and 2010, income tax benefit on share-based compensation expense was $12 million, $16 million, and $13 million, respectively. See Note 20—Share-Based Compensation Plans. Capitalized interest—We capitalize interest costs for qualifying construction and upgrade projects. In the years ended December 31, 2012, 2011 and 2010, we capitalized interest costs on construction work in progress of $54 million, $39 million and $89 million, respectively. Foreign currency—The majority of our revenues and expenditures are denominated in U.S. dollars to limit our exposure to currency exchange rate fluctuations, resulting in the use of the U.S. dollar as the functional currency for all of our operations. We recognize foreign currency exchange gains and losses in other, net. In the years ended December 31, 2012, 2011 and 2010, we recognized net foreign currency exchange gains (losses) of $(27) million, $(99) million and $1 million, respectively. See Note 15—Derivatives and Hedging. Income taxes—We provide for income taxes based upon the tax laws and rates in effect in the countries in which operations are conducted and income is earned. There is little or no expected relationship between the provision for or benefit from income taxes and income or loss before income taxes because the countries in which we operate have taxation regimes that vary not only with respect to nominal rate, but also in terms of the availability of deductions, credits and other benefits. Variations also arise because income earned and taxed in any particular country or countries may fluctuate from year to year. We recognize deferred tax assets and liabilities for the anticipated future tax effects of temporary differences between the financial statement basis and the tax basis of our assets and liabilities using the applicable jurisdictional tax rates in effect at year end. We record a valuation allowance for deferred tax assets when it is more likely than not that some or all of the benefit from the deferred tax asset will not be realized. We provide a valuation allowance to offset deferred tax assets for net operating losses incurred during the year in certain jurisdictions and for other deferred tax assets where, in our opinion, it is more likely than not that the financial statement benefit of these losses will not be realized. We provide a valuation allowance for foreign tax credit carryforwards to reflect the possible expiration of these benefits prior to their utilization. We maintain liabilities for estimated tax exposures in our jurisdictions of operation, and the provisions and benefits resulting from changes to those liabilities are included in our annual tax provision along with related interest and penalties. Tax exposure items include potential challenges to permanent establishment positions, intercompany pricing, disposition transactions, and withholding tax rates and their applicability. These exposures are resolved primarily through the settlement of audits within these tax jurisdictions or by judicial means, but can also be affected by changes in applicable tax law or other factors, which could cause us to revise past estimates. See Note 8—Income Taxes. Cash and cash equivalents—Cash equivalents are highly liquid debt instruments with original maturities of three months or less that may include time deposits with commercial banks that have high credit ratings, U.S. Treasury and government securities, Eurodollar time deposits, certificates of deposit and commercial paper. We may also invest excess funds in no-load, open-end, management investment trusts (“management trusts”). The management trusts invest exclusively in high-quality money market instruments. We maintain restricted cash investments that are pledged for debt service, as required under certain bank credit agreements. We classify such restricted cash investment balances in other current assets if the restriction is expected to expire within one year and in other assets if the restriction is expected to expire in greater than one year. At December 31, 2012, the aggregate carrying amount of our restricted cash investments was $857 million, of which $195 million and $662 million was classified in other current assets and other assets, respectively. At December 31, 2011, the aggregate carrying amount of our restricted cash investments was $934 million, of which $182 million and $752 million was classified in other current assets and other assets, respectively. See Note 14—Debt. Accounts receivable—We derive a majority of our revenues from services to international oil companies and government-owned or government-controlled oil companies. We evaluate the credit quality of our customers on an ongoing basis, and we do not generally require collateral or other security to support customer receivables. We establish an allowance for doubtful accounts on a case-by-case basis, considering changes in the financial position of a major customer, when we believe the required payment of specific amounts owed to us is unlikely to occur. At December 31, 2012 and 2011, the allowance for doubtful accounts was $20 million and $28 million, respectively. Materials and supplies—We record materials and supplies at their average cost less an allowance for obsolescence. We estimate the allowance for obsolescence based on historical experience and expectations for future use of the materials and supplies. At December 31, 2012 and 2011, the allowance for obsolescence was $66 million and $73 million, respectively. Assets held for sale—We classify an asset as held for sale when the facts and circumstances meet the criteria for such classification, including the following: (a) we have committed to a plan to sell the asset, (b) the asset is available for immediate sale, (c) we have initiated actions to complete the sale, including locating a buyer, (d) the sale is expected to be completed within one year, (e) the asset is being actively marketed at a price that is reasonable relative to its fair value, and (f) the plan to sell is unlikely to be subject to significant changes or termination. At December 31, 2012 and 2011, assets held for sale were $179 million and $26 million, respectively. See Note 9—Discontinued Operations. Property and equipment—The carrying amounts of our property and equipment, consisting primarily of offshore drilling rigs and related equipment, are based on our estimates, assumptions and judgments relative to capitalized costs, useful lives and salvage values of our rigs. These estimates, assumptions and judgments reflect both historical experience and expectations regarding future industry conditions and operations. At December 31, 2012, the aggregate carrying amount of our property and equipment represented approximately 61 percent of our total assets. We compute depreciation using the straight-line method after allowing for salvage values. We capitalize expenditures for renewals, replacements and improvements, and we expense maintenance and repair costs as incurred. Upon sale or other disposition of an asset, we recognize a net gain or loss on disposal of the asset, which is measured as the difference between the net carrying amount of the asset and the net proceeds received. Estimated original useful lives of our drilling units range from 18 to 35 years, our buildings and improvements range from 10 to 30 years and our machinery and equipment range from four to 12 years. From time to time, we may review the estimated remaining useful lives of our drilling units, and we may extend the useful life when events and circumstances indicate a drilling unit can operate beyond its remaining useful life. During the year ended December 31, 2012, we adjusted the useful lives for three rigs, extending the estimated useful lives from between 29 and 30 years to between 35 and 38 years. During the year ended December 31, 2011, we adjusted the useful lives for two rigs, extending the estimated useful lives from between 20 and 30 years to between 23 and 38 years. During the year ended December 31, 2010, we adjusted the useful lives for five rigs, extending the estimated useful lives from between 20 and 36 years to between 25 and 39 years. We deemed the life extensions appropriate for each of these rigs based on the respective contracts under which the rigs were operating and the additional life-extending work, upgrades and inspections we performed on the rigs. In each of the years ended December 31, 2012, 2011 and 2010, the changes in estimated useful lives of these rigs resulted in a reduction in annual depreciation expense of $27 million ($0.08 per diluted share from continuing operations), $2 million ($0.01 per diluted share from continuing operations) and $23 million ($0.07 per diluted share from continuing operations), respectively, which had no tax effect for any period. Long-lived assets and definite-lived intangible assets—We review the carrying amounts of long-lived assets and definite-lived intangible assets, principally property and equipment for potential impairment when events occur or circumstances change that indicate that the carrying value of such assets may not be recoverable. For assets classified as held and used, we determine recoverability by evaluating the undiscounted estimated future net cash flows, based on projected dayrates and utilization, of the asset group under review. We consider our asset groups to be Ultra-Deepwater Floaters, Deepwater Floaters, Harsh Environment Floaters, Midwater Floaters and High-Specification Jackups. When an impairment of one or more of our asset groups is indicated, we measure the impairment as the amount by which the asset group’s carrying amount exceeds its estimated fair value. We measure the fair values of our contract drilling asset groups by applying a combination of income and market approaches, using projected discounted cash flows and estimates of the exchange price that would be received for the assets in the principal or most advantageous market for the assets in an orderly transaction between market participants as of the measurement date. For our drilling management services customer relationships asset, we estimate fair value using the excess earnings method, which applies the income approach. For an asset classified as held for sale, we consider the asset to be impaired to the extent its carrying amount exceeds its estimated fair value less cost to sell. In the year ended December 31, 2012, we determined that the customer relationships intangible asset associated with our drilling management services reporting unit was impaired, and we recognized a loss on impairment of $22 million ($17 million, or $0.05 per diluted share, net of tax). Goodwill and other indefinite-lived intangible assets—We conduct impairment testing for our goodwill and other indefinite-lived intangible assets annually as of October 1 and more frequently, on an interim basis, when an event occurs or circumstances change that may indicate a reduction in the fair value of a reporting unit or the indefinite-lived intangible asset is below its carrying value. We test goodwill at the reporting unit level, which is defined as an operating segment or one level below an operating segment that constitutes a business for which financial information is available and is regularly reviewed by management. We have identified two reporting units for this purpose: (1) contract drilling services and (2) drilling management services. Before testing goodwill, we consider whether or not to first assess qualitative factors to determine whether the existence of events or circumstances lead to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount and whether the two-step impairment test is required. If, as the result of our qualitative assessment, we determine that the two-step impairment test is required, or, alternatively, if we elect to forgo the qualitative assessment, we test goodwill for impairment by comparing the carrying amount of the reporting unit, including goodwill, to the fair value of the reporting unit. For our contract drilling services reporting unit, we estimate fair value using projected discounted cash flows, publicly traded company multiples and acquisition multiples. To develop the projected cash flows associated with our contract drilling services reporting unit, which are based on estimated future dayrates and utilization, we consider key factors that include assumptions regarding future commodity prices, credit market conditions and the effect these factors may have on our contract drilling operations and the capital expenditure budgets of our customers. We discount the projected cash flows using a long-term, risk-adjusted weighted-average cost of capital, which is based on our estimate of the investment returns that market participants would require for each of our reporting units. We derive publicly traded company multiples for companies with operations similar to our reporting units using observable information related to shares traded on stock exchanges and, when available, observable information related to recent acquisitions. If the reporting unit’s carrying amount exceeds its fair value, we consider goodwill impaired and perform a second step to measure the amount of the impairment loss, if any. As a result of our annual impairment test, performed as of October 1, 2011, we determined that the goodwill associated with our contract drilling services reporting unit was impaired due to a decline in projected cash flows and market valuations for this reporting unit. In the year ended December 31, 2011, we recognized a loss on impairment, representing our best estimate, in the amount of $5.2 billion ($16.15 per diluted share from continuing operations), which had no tax effect. In the three months ended March 31, 2012, we completed our analysis and recognized an incremental adjustment to our original estimate in the amount of $118 million ($0.33 per diluted share from continuing operations), which had no tax effect. As a result of our annual goodwill impairment test in the years ended December 31, 2012 and 2010, we concluded that goodwill was not impaired. See Note 7—Intangible Asset Impairments and Note 13—Goodwill and Other Intangible Assets. Derivatives and hedging—From time to time, we may enter into a variety of derivative financial instruments in connection with the management of our exposure to variability in interest rates and currency exchange rates. We record derivatives on our consolidated balance sheet, measured at fair value. For derivatives that do not qualify for hedge accounting, we recognize the gains and losses associated with changes in the fair value in current period earnings. We may enter into cash flow hedges to manage our exposure to variability of the expected future cash flows of recognized assets or liabilities or of unrecognized forecasted transactions. For a derivative that is designated and qualifies as a cash flow hedge, we initially recognize the effective portion of the gains or losses in other comprehensive income and subsequently recognize the gains and losses in earnings in the period in which the hedged forecasted transaction affects earnings. We recognize the gains and losses associated with the ineffective portion of the hedges in interest expense in the period in which they are realized. We may enter into fair value hedges to manage our exposure to changes in fair value of recognized assets or liabilities, such as fixed-rate debt, or of unrecognized firm commitments. For a derivative that is designated and qualifies as a fair value hedge, we simultaneously recognize in current period earnings the gains or losses on the derivative along with the offsetting losses or gains on the hedged item attributable to the hedged risk. The resulting ineffective portion, which is measured as the difference between the change in fair value of the derivative and the hedged item, is recognized in current period earnings. See Note 15—Derivatives and Hedging, Note 23—Financial Instruments and Note 24—Risk Concentration. Pension and other postretirement benefits—We use a measurement date of January 1 for determining net periodic benefit costs and December 31 for determining benefit obligations and the fair value of plan assets. We determine our net periodic benefit costs based on a market-related value of assets that reduces year-to-year volatility by including investment gains or losses subject to amortization over a five-year period from the year in which they occur. Investment gains or losses for this purpose are measured as the difference between the expected return calculated using the market-related value of assets and the actual return based on the market-related value of assets. If gains or losses exceed 10 percent of the greater of plan assets or plan liabilities, we amortize such gains or losses over the average expected future service period of the employee participants. We measure our actuarially determined obligations and related costs for our defined benefit pension and other postretirement benefit plans, retiree life insurance and medical benefits, by applying assumptions, including long-term rate of return on plan assets, discount rates, compensation increases, employee turnover rates and health care cost trend rates. The two most critical assumptions are the long-term rate of return on plan assets and the discount rate. For the long-term rate of return, we develop our assumptions regarding the expected rate of return on plan assets based on historical experience and projected long-term investment returns, which are weighted to consider each plan’s target asset allocation. For the discount rate, we base our assumptions on a yield curve approach using Aa-rated corporate bonds and the expected timing of future benefit payments. For the projected compensation trend rate, we consider short-term and long-term compensation expectations for participants, including salary increases and performance bonus payments. For the health care cost trend rate for other postretirement benefits, we establish our assumptions for health care cost trends, applying an initial trend rate that reflects both our recent historical experience and broader national statistics with an ultimate trend rate that assumes that the portion of gross domestic product devoted to health care eventually becomes constant. At December 31, 2012 and 2011, pension and other postretirement benefit plan obligations represented an aggregate liability in the amount of their net underfunded status of $639 million and $640 million, respectively. In the years ended December 31, 2012, 2011 and 2010, net periodic benefit costs were $149 million, $88 million and $91 million, respectively. See Note 16—Postemployment Benefit Plans. Contingencies—We perform assessments of our contingencies on an ongoing basis to evaluate the appropriateness of our liabilities and disclosures for such contingencies. We establish liabilities for estimated loss contingencies when we believe a loss is probable and the amount of the probable loss can be reasonably estimated. We recognize corresponding assets for those loss contingencies that we believe are probable of being recovered through insurance. Once established, we adjust the carrying amount of a contingent liability upon the occurrence of a recognizable event when facts and circumstances change, altering our previous assumptions with respect to the likelihood or amount of loss. We recognize liabilities for legal costs as they are incurred, and we recognize a corresponding asset for those legal costs only if we expect such legal costs to be recovered through insurance. Reclassifications—We have made certain reclassifications, which did not have an effect on net income, to prior period amounts to conform with the current year’s presentation, including certain reclassifications to our consolidated statements of financial position, results of operations and cash flows to present our Standard Jackup and swamp barge disposal groups and our U.S. Gulf of Mexico drilling management services operations as discontinued operations (see Note 9—Discontinued Operations). Other reclassifications did not have a material effect on our consolidated statement of financial position, results of operations or cash flows. Subsequent events—We evaluate subsequent events through the time of our filing on the date we issue our financial statements. See Note 29—Subsequent Events.

- Definition

The entire disclosure for all significant accounting policies of the reporting entity.

+ References+ Details

New Accounting Pronouncements	12 Months Ended
New Accounting Pronouncements	Dec. 31, 2012
New Accounting Pronouncements
New Accounting Pronouncements	Note 3—New Accounting Pronouncements *Recently Adopted Accounting Standards* Intangibles—goodwill and other—Effective January 1, 2012, we adopted the accounting standards update that amends the goodwill impairment testing requirements by giving an entity the option to first assess qualitative factors to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount and whether the two-step impairment test is required. The update is effective for goodwill impairment tests performed for annual and interim periods beginning after December 15, 2011. Our adoption did not have an effect on our consolidated financial statements. Fair value measurements—Effective January 1, 2012, we adopted the accounting standards update that requires additional disclosure about fair value measurements that involve significant unobservable inputs, including additional quantitative information about the unobservable inputs, a description of valuation techniques used, and a qualitative evaluation of the sensitivity of these measurements. Our adoption did not have a material effect on the disclosures contained in our notes to consolidated financial statements. *Recently Issued Accounting Standards* Balance sheet—Effective January 1, 2013, we will adopt the accounting standards update that expands the disclosure requirements for the offsetting of assets and liabilities related to certain financial instruments and derivative instruments. The update requires disclosures to present both gross information and net information for financial instruments and derivative instruments that are eligible for net presentation due to a right of offset, an enforceable master netting arrangement or similar agreement. The update is effective for interim and annual periods beginning on or after January 1, 2013. We do not expect that our adoption will have a material effect on our condensed consolidated balance sheet or the disclosures contained in our notes to consolidated financial statements.

- Definition

The entire disclosure of changes in accounting principles, including adoption of new accounting pronouncements, that describes the new methods, amount and effects on financial statement line items.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 270

-SubTopic 10

-Section 45

-Paragraph 13

-URI http://asc.fasb.org/extlink&oid=6372559&loc=d3e765-108305

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-Topic 270

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-Section 50

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-Name Accounting Standards Codification

-Glossary Accounting Change

-URI http://asc.fasb.org/extlink&oid=6503790

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-Name Accounting Standards Codification

-Glossary Direct Effects of a Change in Accounting Principle

-URI http://asc.fasb.org/extlink&oid=6510796

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Indirect Effects of a Change in Accounting Principle

-URI http://asc.fasb.org/extlink&oid=6515603

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Change in Accounting Principle

-URI http://asc.fasb.org/extlink&oid=6507316

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-Topic 270

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-Subparagraph (SX 210.10-01.(b)(6))

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-Glossary Retrospective Application

-URI http://asc.fasb.org/extlink&oid=6523989

Reference 12: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 01

-Paragraph b

-Subparagraph 6

-Article 10

+ Details

Correction of Errors in Previously Reported Consolidated Financial Statements

12 Months Ended

Dec. 31, 2012

Correction of Errors in Previously Reported Consolidated Financial Statements

Correction of Errors in Previously Reported Consolidated Financial Statements

Note 4—Correction of Errors in Previously Reported Consolidated Financial Statements

We perform assessments of our contingencies and corresponding assets for insurance recoveries on an ongoing basis to evaluate the appropriateness of our balances and disclosures for such contingencies and insurance recoveries. We establish liabilities for estimated loss contingencies when we believe a loss is probable and the amount of the probable loss can be reasonably estimated. We recognize corresponding assets for those loss contingencies that we believe are probable of being recovered through insurance. In performing these assessments in the three months ended June 30, 2012, we identified an error in our previously issued financial statements for the year ended December 31, 2011 related to the recognition of assets for insurance recoveries related to legal and other costs totaling $67 million, which we have concluded should not have been recorded because they were not probable of recovery.

We assessed the materiality of this error in accordance with the U.S. Securities and Exchange Commission (“SEC”) Staff Accounting Bulletin (“SAB”) No. 99, Materiality and SAB No. 108, Considering the Effects of Prior Year Misstatements when Quantifying Misstatements in Current Year Financial Statements (“SAB 108”), using both the rollover method and the iron curtain method, as defined in SAB 108, and concluded the error, inclusive of other adjustments discussed below, was immaterial to prior years but could have been material to the current year. Under SAB 108, if the prior year error that, if corrected in the current year, would be material to the current year, the prior year financial statements should be corrected, even though such correction previously was immaterial to the prior year financial statements.

In addition to the adjustments related to the assets for insurance recoveries, we recorded other adjustments related to the years ended December 31, 2011 and 2010 and the three months ended March 31, 2012 to correct for immaterial errors for repair and maintenance costs, income taxes, discontinued operations, and the allocation of net income attributable to noncontrolling interest. These other adjustments were not previously recorded in the appropriate periods, as we concluded that they were immaterial to our previously issued consolidated financial statements.

For the year ended December 31, 2011, correction of these errors increased our loss from continuing operations by $31 million and net loss attributable to controlling interest by $29 million. For the year ended December 31, 2010, correction of these errors reduced our income from continuing operations by $19 million and net income attributable to controlling interest by $35 million. We have reflected the corrections in our financial statements for each of the interim periods in the year ended December 31, 2011 as presented in Note 28—Quarterly Results.

The summary of adjustments for increases and (decreases) to net income (loss) from continuing operations and net income (loss) attributable to controlling interest for the applicable periods were as follows (in millions):

	Years ended December 31,
	2011			2010
Legal and other costs	$	(67	)	$	—
Repair and maintenance costs	11			(11		)
Income tax (expense) benefit	16			(4		)
Other immaterial adjustments, net	9			(4		)
Net adjustment to income from continuing operations	(31		)	(19		)
Net adjustment to income from discontinued operations, net of tax	(14		)	—
Net adjustment to net income attributable to noncontrolling interest	16			(16		)
Net adjustment to net income attributable to controlling interest	$	(29	)	$	(35	)

The effects of the corrections of the errors on our consolidated statements of operations and balance sheets are presented in the tables below. Previously reported amounts have been adjusted to reflect the reclassifications associated with our discontinued operations. The corrections of the errors had no effect on our consolidated statements of comprehensive income (loss) other than the effect of the changes to net income (loss) for each period. The corrections of the errors had no effect on the previously reported amounts of operating, investing, and financing cash flows in our consolidated statements of cash flows.

	Year ended December 31, 2011									Year ended December 31, 2010
	Previously reported			Adjustments			As adjusted			Previously reported			Adjustments			As adjusted
Operating revenues
Contract drilling revenues	$	7,413		$	(6	)	$	7,407		$	7,698		$	—		$	7,698
Other revenues	620			—			620			251			—			251
	8,033			(6		)	8,027			7,949			—			7,949
Costs and expenses
Operating and maintenance	6,134			45			6,179			4,204			15			4,219
Depreciation and amortization	1,113			(4		)	1,109			1,009			—			1,009
General and administrative	288			—			288			246			—			246
	7,535			41			7,576			5,459			15			5,474
Loss on impairment	(5,201		)	—			(5,201		)	—			—			—
Gain (loss) on disposal of assets, net	(12		)	—			(12		)	255			—			255
Operating income (loss)	(4,715		)	(47		)	(4,762		)	2,745			(15		)	2,730

Other income (expense), net
Interest income	44			—			44			23			—			23
Interest expense, net of amounts capitalized	(621		)	—			(621		)	(567		)	—			(567		)
Other, net	(99		)	—			(99		)	(31		)	—			(31		)
	(676		)	—			(676		)	(575		)	—			(575		)
Income (loss) from continuing operations before income tax expense	(5,391		)	(47		)	(5,438		)	2,170			(15		)	2,155
Income tax (benefit) expense	340			(16		)	324			288			4			292
Income (loss) from continuing operations	(5,731		)	(31		)	(5,762		)	1,882			(19		)	1,863
Income (loss) from discontinued operations, net of tax	99			(14		)	85			(894		)	—			(894		)

Net income (loss)	(5,632		)	(45		)	(5,677		)	988			(19		)	969
Net income (loss) attributable to noncontrolling interest	93			(16		)	77			27			16			43
Net income (loss) attributable to controlling interest	$	(5,725	)	$	(29	)	$	(5,754	)	$	961		$	(35	)	$	926

Earnings (loss) per share-basic
Earnings (loss) from continuing operations	$	(18.10	)	$	(0.04	)	$	(18.14	)	$	5.77		$	(0.11	)	$	5.66
Earnings (loss) from discontinued operations	0.31			(0.05		)	0.26			(2.78		)	—			(2.78		)
Earnings (loss) per share	$	(17.79	)	$	(0.09	)	$	(17.88	)	$	2.99		$	(0.11	)	$	2.88

Earnings (loss) per share-diluted
Earnings (loss) from continuing operations	$	(18.10	)	$	(0.04	)	$	(18.14	)	$	5.77		$	(0.11	)	$	5.66
Earnings (loss) from discontinued operations	0.31			(0.05		)	0.26			(2.78		)	—			(2.78		)
Earnings (loss) per share	$	(17.79	)	$	(0.09	)	$	(17.88	)	$	2.99		$	(0.11	)	$	2.88

	December 31, 2011									December 31, 2010
	Previously reported			Adjustments			As adjusted			Previously reported			Adjustments			As adjusted
Assets
Cash and cash equivalents	$	4,017		$	—		$	4,017		$	3,394		$	(40	)	$	3,354
Accounts receivable, net
Trade	2,049			—			2,049			1,653			—			1,653
Other	127			—			127			190			—			190
Materials and supplies, net	529			—			529			425			—			425
Deferred income taxes, net	142			—			142			115			—			115
Assets held for sale	26			—			26			—			—			—
Other current assets	719			(73		)	646			418			54			472
Total current assets	7,609			(73		)	7,536			6,195			14			6,209

Property and equipment	24,833			—			24,833			22,149			—			22,149
Property and equipment of consolidated variable interest entities	2,252			—			2,252			2,214			—			2,214
Less accumulated depreciation	6,301			(4		)	6,297			5,244			—			5,244
Property and equipment, net	20,784			4			20,788			19,119			—			19,119
Goodwill	3,205			12			3,217			8,132			—			8,132
Other assets	3,490			1			3,491			3,365			(11		)	3,354
Total assets	$	35,088		$	(56	)	$	35,032		$	36,811		$	3		$	36,814

Liabilities and equity
Accounts payable	$	880		$	—		$	880		$	832		$	—		$	832
Accrued income taxes	86			—			86			109			—			109
Debt due within one year	1,942			—			1,942			1,917			—			1,917
Debt of consolidated variable interest entities due within one year	97			148			245			95			148			243
Other current liabilities	2,353			22			2,375			883			12			895
Total current liabilities	5,358			170			5,528			3,836			160			3,996

Long-term debt	10,756			—			10,756			8,354			—			8,354
Long-term debt of consolidated variable interest entities	741			(148		)	593			855			(148		)	707
Deferred income taxes, net	491			(4		)	487			575			10			585
Other long-term liabilities	1,935			(10		)	1,925			1,791			—			1,791
Total long-term liabilities	13,923			(162		)	13,761			11,575			(138		)	11,437

Commitments and contingencies
Redeemable noncontrolling interest	116			—			116			25			16			41

Shares	4,982			—			4,982			4,482			—			4,482
Additional paid-in capital	7,211			—			7,211			7,504			—			7,504
Treasury shares, at cost	(240		)	—			(240		)	(240		)	—			(240		)
Retained earnings	4,244			(64		)	4,180			9,969			(35		)	9,934
Accumulated other comprehensive loss	(496		)	—			(496		)	(332		)	—			(332		)
Total controlling interest shareholders’ equity	15,701			(64		)	15,637			21,383			(35		)	21,348
Noncontrolling interest	(10		)	—			(10		)	(8		)	—			(8		)
Total equity	15,691			(64		)	15,627			21,375			(35		)	21,340
Total liabilities and equity	$	35,088		$	(56	)	$	35,032		$	36,811		$	3		$	36,814

- Definition

The entire disclosure for reporting accounting changes and error corrections. It includes the conveyance of information necessary for a user of the Company's financial information to understand all aspects and required disclosure information concerning all changes and error corrections reported in the Company's financial statements for the period.

+ References+ Details

Business Combination

12 Months Ended

Dec. 31, 2012

Business Combination

Business Combination

Note 5—Business Combination

On August 14, 2011, we entered into an irrevocable agreement with Aker Capital AS to acquire its 41 percent interest in Aker Drilling. After receiving clearance by the Oslo Stock Exchange on August 26, 2011, we launched an all cash offer for 100 percent of the shares of Aker Drilling for NOK 26.50 per share.

As of October 3, 2011, the acquisition date, we held 99 percent of the shares of Aker Drilling, having paid an aggregate amount of NOK 7.9 billion, equivalent to $1.4 billion. On October 4, 2011, we acquired the remaining noncontrolling interest from holders that were required to tender their shares pursuant to Norwegian law. We believe the acquisition of Aker Drilling enhances the composition of our High-Specification Floater fleet and strengthens our presence in Norway. In accounting for the business combination, we applied the acquisition method of accounting, recording the assets and liabilities of Aker Drilling at their estimated fair values as of the acquisition date. In the year ended December 31, 2011, we incurred acquisition costs of $22 million, recognized in general and administrative expense.

As of October 3, 2011, the acquisition price included the following, measured at estimated fair value: current assets of $323 million, drilling rigs and other property and equipment of $1.8 billion, other assets of $757 million, and the assumption of long-term debt of $1.6 billion and other liabilities of $291 million. The acquired assets included $901 million of cash investments restricted for the payment of certain assumed debt instruments. The excess of the purchase price over the estimated fair value of net assets acquired was approximately $285 million, which was recorded as goodwill.

We included approximately three months of operating results of Aker Drilling in our consolidated results of operations for the year ended December 31, 2011. In the years ended December 31, 2012 and 2011, our contract drilling revenues included approximately $380 million and $100 million, respectively, of contract drilling revenues associated with the operations of Aker Drilling.

Unaudited pro forma combined operating results, assuming the acquisition was completed as of January 1, 2010, were as follows (in millions, except per share data):

	Years ended December 31,
	2011			2010
Operating revenues	$	8,339		$	8,280
Operating income (loss)	(4,616		)	2,848
Income (loss) from continuing operations	(5,664		)	1,899

Per share earnings (loss) from continuing operations
Basic	$	(17.84	)	$	5.77
Diluted	$	(17.84	)	$	5.77

The pro forma financial information includes various adjustments, primarily related to depreciation expense resulting from the fair value adjustments to the acquired property and equipment. The pro forma information is not necessarily indicative of the results of operations had the acquisition of Aker Drilling been completed on the assumed date or the results of operations for any future periods.

- Definition

The entire disclosure for a business combination (or series of individually immaterial business combinations) completed during the period, including background, timing, and recognized assets and liabilities. The disclosure may include leverage buyout transactions (as applicable).

+ References

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+ Details

Variable Interest Entities

12 Months Ended

Dec. 31, 2012

Variable Interest Entities

Variable Interest Entities

Note 6—Variable Interest Entities

Consolidated variable interest entities—The carrying amounts associated with our consolidated variable interest entities, after eliminating the effect of intercompany transactions, were as follows (in millions):

	December 31, 2012						December 31, 2011
	Assets		Liabilities		Net carrying amount		Assets		Liabilities		Net carrying amount
Variable interest entity
TPDI	$	—	$	—	$	—	$	1,562	$	673	$	889
ADDCL	954		296		658		930		334		596
TDSOI	277		15		262		—		—		—
Total	$	1,231	$	311	$	920	$	2,492	$	1,007	$	1,485

Transocean Pacific Drilling Inc. (“TPDI”), a consolidated British Virgin Islands company, Angola Deepwater Drilling Company Limited (“ADDCL”), a consolidated Cayman Islands company, and Transocean Drilling Services Offshore Inc. (“TDSOI”), a consolidated British Virgin Islands Company, were joint venture companies formed to own and operate certain drilling units. We determined that each of these joint venture companies met the criteria of a variable interest entity for accounting purposes because its equity at risk was insufficient to permit it to carry on its activities without additional subordinated financial support from us. We also determined, in each case, that we were the primary beneficiary for accounting purposes since (a) we had the power to direct the construction, marketing and operating activities, which are the activities that most significantly impact each entity’s economic performance, and (b) we had the obligation to absorb losses or the right to receive a majority of the benefits that could be potentially significant to the variable interest entity. As a result, we consolidated TPDI, ADDCL and TDSOI in our consolidated financial statements, we eliminated intercompany transactions, and we presented the interests that were not owned by us as noncontrolling interest on our consolidated balance sheets.

In October 2012, Angco II, a Cayman Islands company, acquired a 30 percent interest in TDSOI, a British Virgin Islands joint venture company formed to own and operate Transocean Honor. We hold the remaining 70 percent interest in TDSOI. Under certain circumstances, Angco II will have the right to exchange its interest in the joint venture for cash at an amount based on an appraisal of the fair value of the jackup, subject to certain adjustments.

On May 31, 2012, TPDI became a wholly owned subsidiary and no longer met the definition of a variable interest entity. See Note 18—Redeemable Noncontrolling Interest.

At December 31, 2012 and 2011, the aggregate carrying amount of assets of our consolidated variable interest entities that were pledged as security for the outstanding debt of our consolidated variable interest entities was $805 million and $2.2 billion, respectively. See Note 14—Debt.

Unconsolidated variable interest entities—As holder of two notes receivable and a lender under a working capital loan, we hold a variable interest in Awilco Drilling plc (“Awilco”), a U.K. company listed on the Oslo Stock Exchange. We determined that Awilco met the definition of a variable interest entity since its equity at risk was insufficient to permit it to carry on its activities without additional subordinated financial support. We believe that we are not the primary beneficiary since we do not have the power to direct the activities that most significantly impact the entity’s economic performance.

The notes receivable were originally accepted in exchange for and are secured by two drilling units. The notes receivable have stated interest rates of nine percent and are payable in scheduled quarterly installments of principal and interest through maturity in January 2015. Borrowings under the working capital loan, also secured by the two drilling units, had a stated interest rate of 10 percent and were payable in scheduled quarterly installments of principal and interest through maturity in January 2013, subject to acceleration under certain conditions. On a quarterly basis, we evaluate the credit quality and financial condition of Awilco with respect to our maximum exposure of loss, represented by the outstanding amounts due. At December 31, 2012 and 2011, the aggregate carrying amount of the notes receivable was $105 million and $110 million, respectively. In October 2012, Awilco repaid the remaining outstanding borrowings under the working capital loan. At December 31, 2011, the aggregate carrying amount of the working capital loan receivable was $29 million.

Intangible Asset Impairments	12 Months Ended
Intangible Asset Impairments	Dec. 31, 2012
Intangible Asset Impairments
Intangible Asset Impairments	Note 7—Intangible Asset Impairments Goodwill—As a result of our annual impairment test, performed as of October 1, 2011, we determined that the goodwill associated with our contract drilling services reporting unit was impaired due to a decline in projected cash flows and market valuations for this reporting unit. In the year ended December 31, 2011, we recognized a loss on impairment, representing our best estimate, in the amount of $5.2 billion ($16.15 per diluted share from continuing operations), which had no tax effect. In the year ended December 31, 2012, we completed our analysis and recognized an incremental adjustment to our original estimate in the amount of $118 million ($0.33 per diluted share from continuing operations), which had no tax effect. We estimated the implied fair value of the goodwill using a variety of valuation methods, including cost, income and market approaches. Our estimate of fair value required us to use significant unobservable inputs, representative of a Level 3 fair value measurement, including assumptions related to the future performance of our contract drilling services reporting unit, such as future commodity prices, projected demand for our services, rig availability and dayrates. Definite-lived intangible assets—During the year ended December 31, 2012, we determined that the customer relationships intangible asset associated with the U.K. operations of our drilling management services reporting unit was impaired due to the diminishing demand for our drilling management services. We estimated the fair value of the customer relationships intangible asset using the multiperiod excess earnings method, a valuation methodology that applies the income approach. We estimated fair value using significant unobservable inputs, representative of a Level 3 fair value measurement, including assumptions related to the future performance of the drilling management services reporting unit, such as future commodity prices, projected demand for our services, rig availability and dayrates. As a result of our valuation, we determined that the carrying amount of the customer relationships intangible asset exceeded its fair value, and we recognized a loss on impairment of $22 million ($17 million, or $0.05 per diluted share from continuing operations, net of tax) in the year ended December 31, 2012. See Note 9—Discontinued Operations.

Income Taxes

12 Months Ended

Dec. 31, 2012

Income Taxes

Income Taxes

Note 8—Income Taxes

Tax rate—Transocean Ltd., a holding company and Swiss resident, is exempt from cantonal and communal income tax in Switzerland, but is subject to Swiss federal income tax. At the federal level, qualifying net dividend income and net capital gains on the sale of qualifying investments in subsidiaries are exempt from Swiss federal income tax. Consequently, Transocean Ltd. expects dividends from its subsidiaries and capital gains from sales of investments in its subsidiaries to be exempt from Swiss federal income tax.

Our provision for income taxes is based on the tax laws and rates applicable in the jurisdictions in which we operate and earn income. The relationship between our provision for or benefit from income taxes and our income or loss before income taxes can vary significantly from period to period considering, among other factors, (a) the overall level of income before income taxes, (b) changes in the blend of income that is taxed based on gross revenues rather than income before taxes, (c) rig movements between taxing jurisdictions and (d) our rig operating structures. Generally, our annual marginal tax rate is lower than our annual effective tax rate.

The components of our provision (benefit) for income taxes were as follows (in millions):

	Years ended December 31,
	2012			2011			2010
Current tax expense	$	183		$	386		$	396
Deferred tax benefit	(133		)	(62		)	(104		)
Income tax expense	$	50		$	324		$	292

The following is a reconciliation of the differences between the income tax expense for our continuing operations computed at the Swiss holding company federal statutory rate of 7.83 percent and our reported provision for income taxes (in millions):

	Years ended December 31,
	2012			2011			2010
Income tax expense at the Swiss federal statutory rate	$	68		$	(426	)	$	168
Taxes on earnings subject to rates different than the Swiss federal statutory rate	141			221			72
Taxes on impairment loss subject to rates different than the Swiss federal statutory rate	5			409			—
Taxes on asset sales subject to rates different than the Swiss federal statutory rate	(1		)	—			—
Taxes on litigation matters subject to rates different than the Swiss federal statutory rate	59			78			—
Changes in unrecognized tax benefits, net	(179		)	40			73
Change in valuation allowance	1			19			4
Benefit from foreign tax credits	(38		)	(28		)	(23		)
Taxes on asset acquisition costs at rates lower than the Swiss federal statutory rate	—			8			—
Other, net	(6		)	3			(2		)
Income tax expense	$	50		$	324		$	292

Deferred taxes—The significant components of our deferred tax assets and liabilities were as follows (in millions):

	December 31,
	2012			2011
Deferred tax assets
Drilling contract intangibles	$	1		$	2
Net operating loss carryforwards	380			331
Tax credit carryforwards	41			45
Accrued payroll expenses not currently deductible	95			79
Deferred income	86			65
Valuation allowance	(210		)	(183		)
Other	108			104
Total deferred tax assets	501			443

Deferred tax liabilities
Depreciation and amortization	(688		)	(746		)
Drilling management services intangibles	—			—
Other	(37		)	(42		)
Total deferred tax liabilities	(725		)	(788		)

Net deferred tax liabilities	$	(224	)	$	(345	)

Our deferred tax assets include U.S. foreign tax credit carryforwards of $41 million, which will expire between 2015 and 2021. Deferred tax assets related to our net operating losses were generated in various worldwide tax jurisdictions. At December 31, 2012 and 2011, the tax effect of our Brazilian net operating losses, which do not expire, was $55 million and $57 million, respectively. In connection with our acquisition of Aker Drilling, we acquired $141 million of Norwegian net operating losses, which do not expire.

The valuation allowance for our non-current deferred tax assets was as follows (in millions):

	December 31,
	2012		2011
Valuation allowance for non-current deferred tax assets	$	210	$	183

Our deferred tax liabilities include taxes related to the earnings of certain subsidiaries that are not permanently reinvested or that will not be permanently reinvested in the future. Should our expectations change regarding future tax consequences, we may be required to record additional deferred taxes that could have a material adverse effect on our consolidated statement of financial position, results of operations or cash flows.

We consider the earnings of certain of our subsidiaries to be indefinitely reinvested. As such, we have not provided for taxes on these unremitted earnings. Should we make a distribution from the unremitted earnings of these subsidiaries, we would be subject to taxes payable to various jurisdictions. At December 31, 2012, the amount of indefinitely reinvested earnings was approximately $2.5 billion. If all of these indefinitely reinvested earnings were distributed, we would be subject to estimated taxes of $180 million to $230 million.

Unrecognized tax benefits—The changes to our liabilities related to unrecognized tax benefits, excluding interest and penalties that we recognize as a component of income tax expense, were as follows (in millions):

	Years ended December 31,
	2012			2011			2010
Balance, beginning of period	$	515		$	485		$	460
Additions for current year tax positions	58			45			46
Additions for prior year tax positions	25			29			9
Reductions for prior year tax positions	(24		)	—			(11		)
Settlements	(120		)	(42		)	(17		)
Reductions related to statute of limitation expirations	(72		)	(2		)	(2		)
Balance, end of period	$	382		$	515		$	485

The liabilities related to our unrecognized tax benefits, including related interest and penalties that we recognize as a component of income tax expense, were as follows (in millions):

	December 31,
	2012		2011
Unrecognized tax benefits, excluding interest and penalties	$	382	$	515
Interest and penalties	199		256
Unrecognized tax benefits, including interest and penalties	$	581	$	771

In the years ended December 31, 2012, 2011 and 2010, we recognized interest and penalties related to our unrecognized tax benefits, recorded as a component of income tax expense, in the amount of $56 million, $20 million and $35 million, respectively. If recognized, $581 million of our unrecognized tax benefits, including interest and penalties, as of December 31, 2012, would favorably impact our effective tax rate.

It is reasonably possible that our existing liabilities for unrecognized tax benefits may increase or decrease in the year ending December 31, 2013 primarily due to the progression of open audits or the expiration of statutes of limitation. However, we cannot reasonably estimate a range of potential changes in our existing liabilities for unrecognized tax benefits due to various uncertainties, such as the unresolved nature of various audits.

Tax returns—We file federal and local tax returns in several jurisdictions throughout the world. With few exceptions, we are no longer subject to examinations of our U.S. and non-U.S. tax matters for years prior to 2006.

Our tax returns in the major jurisdictions in which we operate, other than the U.S., Norway and Brazil, which are mentioned below, are generally subject to examination for periods ranging from three to six years. We have agreed to extensions beyond the statute of limitations in two major jurisdictions for up to 18 years. Tax authorities in certain jurisdictions are examining our tax returns and in some cases have issued assessments. We are defending our tax positions in those jurisdictions. While we cannot predict or provide assurance as to the final outcome of these proceedings, we do not expect the ultimate liability to have a material adverse effect on our consolidated statement of financial position or results of operations, although it may have a material adverse effect on our consolidated cash flows.

U.S. tax investigations—With respect to our 2004 U.S. federal income tax return, the U.S. tax authorities withdrew all of their previously proposed tax adjustments, including all claims related to transfer pricing. In January 2012, a judge in the U.S. Tax Court entered a decision of no deficiency for the 2004 tax year and cancelled the trial previously scheduled to take place in February 2012. With respect to our 2005 U.S. federal income tax returns, the U.S. tax authorities have withdrawn all of their previously proposed tax adjustments. Our 2004 and 2005 U.S. federal income tax returns are now settled and the tax years are now closed.

With respect to our 2006 and 2007 federal income tax returns, we reached an agreement with the U.S. tax authorities in December 2012, to settle all issues, including transfer pricing for certain charters of drilling rigs between our subsidiaries and the creation of intangible assets resulting from the performance of engineering services between our subsidiaries for $11 million of additional tax, excluding interest and penalties, and the tax years are now closed.

In February 2012, we received an assessment from the U.S. tax authorities related to our 2008 and 2009 U.S. federal income tax returns. The significant issues raised in the assessment relate to transfer pricing for certain charters of drilling rigs between our subsidiaries and the creation of intangible assets resulting from the performance of engineering services between our subsidiaries. With respect to transfer pricing issues related to certain charters of drilling rigs in 2008 and 2009, we reached an agreement with the U.S. tax authorities in December 2012, to settle this issue and other issues raised during the audit for $36 million, excluding interest and penalties. The only remaining issue outstanding for these years relates to an asserted creation of intangible assets resulting from the performance of engineering services between our subsidiaries for which a royalty is asserted. The initial assessment issued by the tax authorities on this item, if sustained, would result in net adjustments of approximately $363 million of additional taxes, excluding interest and penalties. An unfavorable outcome on this adjustment could result in a material adverse effect on our consolidated statement of financial position, results of operations or cash flows. Furthermore, if the authorities were to continue to pursue this position with respect to subsequent years and were successful in such assertion, our effective tax rate on worldwide earnings with respect to years following 2009 could increase substantially, and could have a material adverse effect on our consolidated results of operations and cash flows. We believe our U.S. federal income tax returns are materially correct as filed, and we intend to continue to vigorously defend against all such claims.

Norway tax investigations and trial—Norwegian civil tax and criminal authorities are investigating various transactions undertaken by our subsidiaries in 1999, 2001 and 2002 as well as the actions of certain employees of our former external tax advisors on these transactions. The authorities issued tax assessments of approximately $123 million, plus interest, related to the migration of a subsidiary that was previously subject to tax in Norway, approximately $74 million, plus interest, related to a 2001 dividend payment, and approximately $8 million, plus interest, related to certain foreign exchange deductions and dividend withholding tax. We have provided a parent company guarantee in the amount of approximately $125 million with respect to one of these tax disputes. Furthermore, we may be required to provide some form of additional financial security, in an amount up to $218 million, including interest and penalties, for other assessed amounts as these disputes are appealed and addressed by the Norwegian courts. The authorities are seeking penalties of 60 percent on most but not all matters. In November 2012, the Norwegian district court in Oslo heard the case regarding the disputed tax assessment of approximately $123 million related to the migration of our subsidiary. We believe that our Norwegian tax returns are materially correct as filed and if we receive unfavorable outcome at the district court, we expect to appeal the decision. In addition, we expect to file or have filed appeals to the two other tax assessments.

In June 2011, the Norwegian authorities issued criminal indictments against two of our subsidiaries alleging misleading or incomplete disclosures in Norwegian tax returns for the years 1999 through 2002, as well as inaccuracies in Norwegian statutory financial statements for the years ended December 31, 1996 through 2001. The criminal trial commenced in December 2012. Two employees of our former external tax advisors were also issued indictments with respect to the disclosures in our tax returns. In October 2011, the Norwegian authorities issued criminal indictments against a Norwegian tax attorney related to certain of our restructuring transactions and to the 2001 dividend payment. The indicted Norwegian tax attorney worked for us in an advisory capacity on these transactions. We believe the charges brought against us are without merit and do not alter our technical assessment of the underlying claims. In January 2012, the Norwegian authorities supplemented the previously issued criminal indictments by issuing a financial claim of approximately $330 million, jointly and severally, against our two subsidiaries, the two external advisors and the external tax attorney. In February 2012, the authorities dropped the previously existing tax assessment related to a certain restructuring transaction. In April 2012, the Norwegian tax authorities supplemented the previously issued criminal indictments against our two subsidiaries by extending a criminal indictment against a third subsidiary on the same matter, alleging misleading or incomplete disclosures in Norwegian tax returns for the years 2001 and 2002. We believe our Norwegian tax returns are materially correct as filed, and we intend to continue to vigorously contest any assertions to the contrary by the Norwegian civil and criminal authorities in connection with the various transactions being investigated. An unfavorable outcome on the Norwegian civil or criminal tax matters could result in a material adverse effect on our consolidated statement of financial position, results of operations or cash flows. See Note 29—Subsequent Events.

Brazil tax investigations—Certain of our Brazilian income tax returns for the years 2000 through 2004 are currently under examination. The Brazilian tax authorities have issued tax assessments totaling $98 million, plus a 75 percent penalty in the amount of $73 million and interest through December 31, 2011 in the amount of $147 million. We believe our returns are materially correct as filed, and we are vigorously contesting these assessments. On January 25, 2008, we filed a protest letter with the Brazilian tax authorities, and we are currently engaged in the appeals process. An unfavorable outcome on these proposed assessments could result in a material adverse effect on our consolidated statement of financial position, results of operations or cash flows.

Other tax matters—We conduct operations through our various subsidiaries in a number of countries throughout the world. Each country has its own tax regimes with varying nominal rates, deductions and tax attributes. From time to time, we may identify changes to previously evaluated tax positions that could result in adjustments to our recorded assets and liabilities. Although we are unable to predict the outcome of these changes, we do not expect the effect, if any, resulting from these adjustments to have a material adverse effect on our consolidated statement of financial position, results of operations or cash flows.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

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-Paragraph 136, 172

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-Paragraph 43, 44, 45, 46, 47, 48, 49

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Discontinued Operations

12 Months Ended

Dec. 31, 2012

Discontinued Operations

Discontinued Operations

Note 9—Discontinued Operations

Summarized results of discontinued operations

The summarized results of operations included in income from discontinued operations were as follows (in millions):

	Years ended December 31,
	2012			2011			2010
Operating revenues	$	1,055		$	1,171		$	1,627
Operating and maintenance expense	(990		)	(871		)	(916		)
Depreciation and amortization expense	(183		)	(342		)	(580		)
Loss on impairment of assets in discontinued operations, net	(986		)	(38		)	(1,012		)
Gain on disposal of discontinued operations, net	82			183			2
Other income, net	—			18			8
Income (loss) from discontinued operations before income tax expense	(1,022		)	121			(871		)
Income tax expense	(5		)	(36		)	(23		)
Income (loss) from discontinued operations, net of tax	$	(1,027	)	$	85		$	(894	)

Assets and liabilities of discontinued operations

The carrying amounts of the major classes of assets and liabilities associated with our discontinued operations were classified as follows (in millions):

	December 31,
	2012		2011
Assets
Rigs and related equipment, net	$	104	$	—
Materials and supplies	71		—
Oil and gas properties, net	—		24
Other related assets	4		2
Assets held for sale	$	179	$	26

Materials and supplies	$	—	$	98
Other assets	—		21
Other current assets	$	—	$	119

Rig and related equipment, net	$	—	$	1,745
Intangible assets	—		70
Deferred costs	—		42
Other assets	$	—	$	1,857

Liabilities
Deferred revenues	$	32	$	17
Deferred income taxes, net	—		6
Other liabilities	3		14
Other current liabilities	$	35	$	37

Deferred revenues	$	—	$	8
Deferred taxes, net	—		32
Other long-term liabilities	$	—	$	40

Standard Jackup and swamp barge contract drilling operations

Overview—In September 2012, we committed to a plan to discontinue operations associated with the Standard Jackup and swamp barge asset groups, components of our contract drilling services operating segment. As a result of our decision to discontinue operations associated with these components of our contract drilling services operating segment, we allocated $112 million of goodwill to the disposal group based on the fair value of the disposal group relative to the fair value of the contract drilling services operating segment. We estimated the fair value of the disposal group and the contract drilling services operating segment using a variety of valuation methods, including the income and market approaches. We estimated fair value using significant unobservable inputs, representative of a Level 3 fair value measurement, including assumptions related to the future performance of the disposal group and of our contract drilling services reporting unit, such as future commodity prices, projected demand for our services, rig availability and dayrates.

At December 31, 2012, the remaining Standard Jackups, which were not sold in the sale transactions with Shelf Drilling, including D.R. Stewart, GSF Adriatic VIII, GSF Rig 127, GSF Rig 134, Interocean III, Trident IV-A and Trident VI, and related equipment, were classified as held for sale with an aggregate carrying amount of $112 million, including $8 million in materials and supplies.

Impairments—In September 2012, in connection with our reclassification of the Standard Jackup and swamp barge disposal group to assets held for sale, we determined that the disposal group was impaired since its aggregate carrying amount exceeded its aggregate fair value. We estimated the fair value of this disposal group by applying a variety of valuation methods, including cost, income and market approaches, to estimate the exit price that would be received for the assets in the principal or most advantageous market for the assets in an orderly transaction between market participants as of the measurement date. Although we based certain components of our valuation on significant other observable inputs, including binding sale and purchase agreements, we estimated fair value using significant unobservable inputs, representative of a Level 3 fair value measurement, including assumptions related to the future performance of the disposal group, such as long-term projections for future revenues and costs, dayrates, rig utilization and idle time. We measured the impairments of the disposal group as the amount by which the carrying amounts exceeded its estimated fair value less costs to sell. Included in the loss on impairment, we recognized $20 million of personnel costs relating to postemployment obligations for certain employees and contract labor. The loss on impairment also included approximately $60 million of costs for the required reactivation of one drilling unit pursuant to the sale agreement and approximately $17 million of costs to sell the disposal group, including legal and financial advisory costs and expenses. In the year ended December 31, 2012, as a result of our valuation, we recognized losses of $744 million ($2.08 per diluted share) and $112 million ($0.31 per diluted share), with no tax effect, associated with the impairment of long-lived assets and the goodwill, respectively.

In the year ended December 31, 2012, we also recognized aggregate losses of $29 million ($0.08 per diluted share), which had no tax effect, associated with the impairment of the Standard Jackups GSF Adriatic II and GSF Rig 136, which were classified as assets held for sale at the time of impairment. In the year ended December 31, 2011, we recognized aggregate losses of $28 million ($0.09 per diluted share), which had a tax effect of less than $1 million, associated with the impairment of the Standard Jackups George H. Galloway, GSF Britannia, GSF Labrador and the swamp barge Searex IV, which were classified as assets held for sale at the time of impairment. We measured the impairments of the drilling units and related equipment as the amount by which the carrying amounts exceeded the estimated fair values less costs to sell. We estimated the fair value of the assets using significant other observable inputs, representative of Level 2 fair value measurements, including binding sale and purchase agreements for the drilling units and related equipment.

During the year ended December 31, 2010, we determined that the Standard Jackup asset group in our contract drilling services reporting unit was impaired due to projected declines in dayrates and utilization rates. We measured the fair value of this asset group by applying a combination of income and market approaches, using projected discounted cash flows and estimates of the exchange price that would be received for the assets in the principal or most advantageous market for the assets in an orderly transaction between market participants as of the measurement date. We estimated the fair value using significant unobservable inputs, representative of a Level 3 fair value measurement, including assumptions related to the future performance of the asset group, such as long-term projections for future revenues and costs, dayrates, rig utilization rates and idle time. As a result, we determined that the carrying amount of the Standard Jackup asset group exceeded its fair value, and in the year ended December 31, 2010, we recognized a loss on impairment of long-lived assets in the amount of $1.0 billion ($3.13 per diluted share), which had no tax effect.

Sale transactions with Shelf Drilling—On November 30, 2012, we completed the sale of 38 drilling units to Shelf Drilling. Such drilling units included the Standard Jackup GSF Baltic, which was formerly classified as a High-Specification Jackup, the Standard Jackups C.E. Thornton, F.G. McClintock, GSF Adriatic I, GSF Adriatic V, GSF Adriatic VI, GSF Adriatic IX, GSF Adriatic X, GSF Compact Driller, GSF Galveston Key, GSF High Island II, GSF High Island IV, GSF High Island V, GSF High Island VII, GSF High Island IX, GSF Key Gibraltar, GSF Key Hawaii, GSF Key Manhattan, GSF Key Singapore, GSF Main Pass I, GSF Main Pass IV, GSF Parameswara, GSF Rig 105, GSF Rig 124, GSF Rig 141, Harvey H. Ward, J.T. Angel, Randolph Yost, Ron Tappmeyer, Transocean Comet, Trident II, Trident VIII, Trident IX, Trident XII, Trident XIV, Trident XV and Trident XVI and the swamp barge Hibiscus, along with related equipment.

In connection with the sale, we received cash proceeds of $568 million, net of certain working capital and other adjustments, and non-cash proceeds in the form of perpetual preference shares that had a stated value of $196 million and an estimated fair value of $194 million, including the fair value associated with embedded derivatives, at the closing of the transaction. Although we based certain components of our valuation of the preference shares on significant other observable inputs, such as market dividend rates and projected oil prices, we estimated fair value using significant unobservable inputs, representative of a Level 3 fair value measurement, including the credit ratings and financial position of the investee. As a result of the sale transactions with Shelf Drilling, in the year ended December 31, 2012, we recognized a gain on the disposal of the assets sold in the amount of $8 million (net loss of $5 million or $0.01 per diluted share, net of tax), subject to working capital and other adjustments currently under review by us and Shelf Drilling pursuant to the terms of the sales agreements. Such adjustments, if not resolved between us and Shelf Drilling within the period of time stipulated in the agreements will become subject to a dispute resolution process. While we cannot provide assurance as to the final resolution of the adjustments, we do not expect it to have a material adverse effect on our consolidated statement of financial position, results of operations or cash flows.

The ultimate parent company of Shelf Drilling is a newly formed company sponsored equally by three private equity firms. The preference shares received in the sale transactions represent an interest in an intermediate parent company of Shelf Drilling. As holder of the preference shares, we are entitled to cumulative dividends, payable in-kind, at 10 percent per annum, escalating two percent biannually to a maximum of 14 percent but subject to reductions or increases under certain circumstances. The preference shares contain two embedded derivatives, including (a) a ceiling dividend rate indexed to the price of Brent Crude oil and (b) a dividend rate premium triggered in the event of credit default (see Note 15—Derivatives and Hedging). The preference shares are subject to mandatory redemption upon certain specified events outside of our control, including an initial public offering or change of control of Shelf Drilling.

For a transition period following the completion of the sale transactions, we agreed to continue to operate a substantial portion of the Standard Jackups under operating agreements with Shelf Drilling and to provide certain other transition services to Shelf Drilling. The costs to us of providing such operating and transition services may exceed the amounts we receive from Shelf Drilling as compensation for providing such services. Under the operating agreements, we agreed to continue to operate these Standard Jackups on behalf of Shelf Drilling for periods ranging from nine months to 27 months, until expiration or novation of the underlying drilling contracts by Shelf Drilling. As of December 31, 2012, we operated 25 Standard Jackups under operating agreements with Shelf Drilling. Under a transition services agreement, we agreed to provide certain transition services for a period of up to 18 months following the completion of the sale transactions.

For a period of up to three years following the closing of the sale transactions, we have agreed to provide to Shelf Drilling up to $125 million of financial support by maintaining letters of credit, surety bonds and guarantees for various contract bidding and performance activities associated with the drilling units sold to Shelf Drilling and in effect at the closing of the sale transactions. At the time of the sale transactions, we had $113 million of outstanding letters of credit, issued under our committed and uncommitted credit lines, in support of rigs sold to Shelf Drilling. Included within the $125 million maximum amount, we agreed to provide up to $65 million of additional financial support in connection with any new drilling contracts related to such drilling units. Shelf Drilling is required to reimburse us in the event that any of these instruments are called. At December 31, 2012, we had $113 million of outstanding letters of credit, issued under our committed and uncommitted credit lines, in support of drilling units sold to Shelf Drilling. See Note 17—Commitments and Contingencies.

Other dispositions—During the year ended December 31, 2012, we also completed the sales of the Standard Jackups GSF Adriatic II, GSF Rig 103, GSF Rig 136, Roger W. Mowell, Transocean Nordic, Transocean Shelf Explorer and Trident 17, along with related equipment. During the year ended December 31, 2011, we completed the sales of the Standard Jackups George H. Galloway, GSF Adriatic XI, GSF Britannia, GSF Labrador and Transocean Mercury and the swamp barge Searex IV, along with related equipment, and our ownership interest in Joides Resolution. In connection with the disposal of these assets, in the years ended December 31, 2012 and 2011, we received aggregate net cash proceeds of $201 million and $185 million, and we recognized an aggregate net gain on disposal of these assets in the amount of $74 million ($0.20 per diluted share) and $32 million ($0.10 per diluted share), respectively, which had no tax effect in either period. In the years ended December 31, 2012 and 2011, we recognized losses on the disposal of unrelated assets in the amount of $9 million and $1 million, respectively.

In December 2012, we entered into agreements to sell the Standard Jackups D.R. Stewart and GSF Adriatic VIII and related equipment. See Note 29—Subsequent Events.

Caspian Sea contract drilling operations

Overview—In February 2011, in connection with our efforts to dispose of non-strategic assets, we sold the subsidiary that owns the High-Specification Jackup Trident 20, located in the Caspian Sea. The disposal of this subsidiary, a component of our contract drilling services operating segment, reflects our decision to discontinue operations in the Caspian Sea. Through June 2011, we continued to operate Trident 20 under a bareboat charter to perform services for the customer and the buyer reimbursed us for the approximate cost of providing these services. Additionally, we provided certain transition services to the buyer through September 2011.

Disposition—In the year ended December 31, 2011, in connection with the sale of the High-Specification Jackup Trident 20, we received net cash proceeds of $259 million and recognized a gain on the disposal of the assets of $169 million ($0.52 per diluted share), which had no tax effect.

U.S. Gulf of Mexico drilling management services

Overview—In March 2012, we announced our intent to discontinue drilling management operations in the shallow waters of the U.S. Gulf of Mexico, a component of our drilling management services segment, upon completion of our then existing contracts. We based our decision to abandon this market on the declining market outlook for these services in the shallow waters of the U.S. Gulf of Mexico as well as the more difficult regulatory environment for obtaining drilling permits. In December 2012, we completed the final drilling management project and discontinued offering our drilling management services in this region.

Impairments—During the year ended December 31, 2012, we determined that the customer relationships intangible asset associated with the U.S. operations of our drilling management services reporting unit was impaired due to the declining market outlook for these services in the shallow waters of the U.S. Gulf of Mexico as well as the increased regulatory environment for obtaining drilling permits and the diminishing demand for our drilling management services. We estimated the fair value of the customer relationships intangible asset using the multiperiod excess earnings method, a valuation methodology that applies the income approach. We estimated fair value using significant unobservable inputs, representative of a Level 3 fair value measurement, including assumptions related to the future performance of the drilling management services reporting unit, such as future commodity prices, projected demand for our services, rig availability and dayrates. As a result of our valuation, we determined that the carrying amount of the customer relationships intangible asset exceeded its fair value, and we recognized a loss on impairment of $31 million ($20 million or $0.06 per diluted share, net of tax) in the year ended December 31, 2012.

During the year ended December 31, 2012, we determined that the trade name intangible asset associated with our drilling management services reporting unit was impaired due to the declining market outlook for these services in the shallow waters of the U.S. Gulf of Mexico as well as the increased regulatory environment for obtaining drilling permits and the diminishing demand for drilling management services. We estimated the fair value of the trade name intangible asset using the relief from royalty method, a valuation methodology that applies the income approach. We estimated fair value using significant unobservable inputs, representative of a Level 3 fair value measurement, including assumptions related to the future performance of the drilling management services reporting unit, such as future commodity prices, projected demand for drilling management services, rig availability and dayrates. As a result of our valuation, we determined that the carrying amount of the trade name intangible asset exceeded its fair value, and we recognized a loss on impairment of $39 million ($25 million or $0.07 per diluted share, net of tax) in the year ended December 31, 2012.

Oil and gas properties

Overview—In March 2011, in connection with our efforts to dispose of non-strategic assets, we engaged an unaffiliated advisor to coordinate the sale of the assets of our oil and gas properties reporting unit, formerly a component of our other operations segment, which comprised the exploration, development and production activities performed by CMI.

Impairments—In the year ended December 31, 2012, we recognized losses of $11 million ($10 million or $0.02 per diluted share, net of tax) associated with the impairment of our oil and gas properties, which were classified as assets held for sale, since the carrying amount of the properties exceeded the estimated fair value less costs to sell the properties. In the year ended December 31, 2011, we recognized a loss of $10 million ($6 million or $0.02 per diluted share, net of tax) associated with the impairment of our oil and gas properties, which were classified as assets held for sale, since the carrying amount of the properties exceeded the estimated fair value less costs to sell the properties. We estimated fair value based on significant other observable inputs, representative of a Level 2 fair value measurement, including a binding sale and purchase agreement for the properties.

Dispositions—In October 2011, we completed the sale of Challenger Minerals (North Sea) Limited for aggregate net cash proceeds of $24 million, and in May 2012, we received additional cash proceeds of $10 million. During the year ended December 31, 2012, we completed the sales of the assets of Challenger Minerals Inc. and Challenger Minerals (Ghana) Limited for aggregate net cash proceeds of $7 million and $6 million, respectively. In the year ended December 31, 2012, in connection with these disposals, we recognized an aggregate net gain of $9 million ($0.02 per diluted share), which had no tax effect. In the year ended December 31, 2011, in connection with these disposals, we recognized an aggregate net loss of $4 million (aggregate net gain of $14 million or $0.05, net of tax).

- Definition

The entire disclosure for the facts and circumstances leading to the completed or expected disposal, manner and timing of disposal, the gain (loss) recognized in the income statement and the income statement caption that includes that gain (loss), amounts of revenues and pretax profit or loss reported in discontinued operations, the segment in which the disposal group was reported, and the classification (whether sold or classified as held for sale) and carrying value of the assets and liabilities comprising the disposal group. Includes all disposal groups, including those classified as components of the entity (discontinued operations).

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+ Details

Earnings (Loss) Per Share

12 Months Ended

Dec. 31, 2012

Earnings (Loss) Per Share

Earnings (Loss) Per Share

Note 10—Earnings (Loss) Per Share

The numerator and denominator used for the computation of basic and diluted per share earnings from continuing operations were as follows (in millions, except per share data):

	Years ended December 31,
	2012				2011						2010
	Basic		Diluted		Basic			Diluted			Basic			Diluted
Numerator for earnings (loss) per share
Income (loss) from continuing operations attributable to controlling interest	$	808	$	808	$	(5,839	)	$	(5,839	)	$	1,820		$	1,820
Undistributed earnings allocable to participating securities	—		—		—			—			(10		)	(10		)
Income (loss) from continuing operations available to shareholders	$	808	$	808	$	(5,839	)	$	(5,839	)	$	1,810		$	1,810

Denominator for earnings (loss) per share
Weighted-average shares outstanding	356		356		322			322			320			320
Effect of stock options and other share-based awards	—		—		—			—			—			—
Weighted-average shares for per share calculation	356		356		322			322			320			320

Per share earnings (loss) from continuing operations	$	2.27	$	2.27	$	(18.14	)	$	(18.14	)	$	5.66		$	5.66

For the years ended December 31, 2012, 2011 and 2010, respectively, we have excluded 2.4 million, 2.4 million and 2.2 million share-based awards from the calculation since the effect would have been anti-dilutive. The 1.625% Series A Convertible Senior Notes, 1.50% Series B Convertible Senior Notes and 1.50% Series C Convertible Senior Notes did not have an effect on the calculation for the periods presented. See Note 14—Debt.

- Definition

The entire disclosure for earnings per share.

+ References+ Details

Other Comprehensive Income (Loss)

12 Months Ended

Dec. 31, 2012

Other Comprehensive Income (Loss)

Other Comprehensive Income (Loss)

Note 11—Other Comprehensive Income (Loss)

The allocation of other comprehensive income (loss) attributable to controlling interest and to noncontrolling interest was as follows (in millions):

	Years ended December 31,
	2012									2011									2010
	Controlling interest			Non- controlling interest (a)			Total			Controlling interest			Non- controlling interest (a)			Total			Controlling interest			Non- controlling interest (a)			Total
Unrecognized components of net periodic benefit costs	$	(52	)	$	—		$	(52	)	$	(204	)	$	—		$	(204	)	$	(8	)	$	—		$	(8	)
Unrecognized gain (loss) on derivative instruments	6			(3		)	3			3			(16		)	(13		)	(10		)	(19		)	(29		)
Unrecognized loss on marketable securities	—			—			—			(13		)	—			(13		)	—			—			—
Recognized components of net periodic benefit costs	47			—			47			25			—			25			16			—			16
Recognized (gain) loss on derivative instruments	(4		)	3			(1		)	(1		)	12			11			14			(2		)	12
Recognized loss on marketable securities	2			—			2			13			—			13			—			—			—

Other comprehensive income (loss) before income taxes	(1		)	—			(1		)	(177		)	(4		)	(181		)	12			(21		)	(9		)
Income taxes related to other comprehensive income (loss)	(7		)	—			(7		)	13			—			13			(9		)	—			(9		)
Other comprehensive income (loss), net of tax	$	(8	)	$	—		$	(8	)	$	(164	)	$	(4	)	$	(168	)	$	3		$	(21	)	$	(18	)

(a) Includes amounts attributable to noncontrolling interest and redeemable noncontrolling interest.

- Definition

The entire disclosure for comprehensive income, which includes, but is not limited to, 1) the amount of income tax expense or benefit allocated to each component of other comprehensive income, including reclassification adjustments, 2) the reclassification adjustments for each classification of other comprehensive income and 3) the ending accumulated balances for each component of comprehensive income.

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+ Details

Drilling Fleet

12 Months Ended

Dec. 31, 2012

Drilling Fleet

Drilling Fleet

Note 12—Drilling Fleet

Construction work in progress—Capital expenditures and other capital additions, including capitalized interest, for each of the three years ended December 31, 2012 were as follows (in millions):

	Years ended December 31,
	2012			2011			2010
Construction work in progress, at beginning of period	$	1,360		$	1,450		$	3,657

Newbuild construction program
Ultra-Deepwater Floater TBN1 (a)	139			—			—
Ultra-Deepwater Floater TBN2 (a)	128			—			—
Ultra-Deepwater Floater TBN3 (a)	76			—			—
Ultra-Deepwater Floater TBN4 (a)	76			—			—
Transocean Ao Thai (b)	72			80			—
Deepwater Asgard (c)	46			4			—
Deepwater Invictus (c)	40			3			—
Transocean Siam Driller (b)	39			113			9
Transocean Andaman (b)	38			113			9
Transocean Honor (d)	35			129			98
Deepwater Champion (e)	—			76			249
Discoverer India (f)	—			—			262
Discoverer Luanda (g)	—			—			212
Dhirubhai Deepwater KG2 (h)	—			—			45
Discoverer Inspiration (h)	—			—			33
Other construction projects and capital additions	614			456			432
Total capital expenditures	1,303			974			1,349
Acquisition of construction work in progress (c)	—			272			—
Changes in accrued capital expenditures	61			(2		)	(57		)

Property and equipment placed into service
Transocean Honor (d)	(262		)	—			—
Deepwater Champion (e)	—			(881		)	—
Discoverer India (f)	—			—			(835		)
Discoverer Luanda (g)	—			—			(783		)
Discoverer Inspiration (h)	—			—			(781		)
Dhirubhai Deepwater KG2 (h)	—			—			(707		)
Other property and equipment	(490		)	(453		)	(393		)
Construction work in progress, at end of period	$	1,972		$	1,360		$	1,450

(a) Our four newbuild Ultra-Deepwater drillships, under construction at the Daewoo Shipbuilding & Marine Engineering Co. Ltd. shipyard in Korea, are expected to commence operations in the fourth quarter of 2015, the second quarter of 2016, the fourth quarter of 2016 and the first quarter of 2017.

(b) Transocean Siam Driller, Transocean Andaman and Transocean Ao Thai, three Keppel FELS Super B class design High-Specification Jackups, under construction at Keppel FELS’ yard in Singapore, are expected to commence operations in the first quarter of 2013, the second quarter of 2013 and the fourth quarter of 2013, respectively.

(c) Deepwater Asgard and Deepwater Invictus, two Ultra-Deepwater drillships under construction at the Daewoo Shipbuilding & Marine Engineering Co. Ltd. shipyard in Korea, are expected to be ready to commence operations in the second quarter of 2014. In the year ended December 31, 2011, we acquired the construction work in progress associated with these Ultra-Deepwater drillships with an aggregate estimated fair value of $272 million. See Note 5—Business Combination.

(d) Transocean Honor, a PPL Pacific Class 400 design High-Specification Jackup, owned through our 70 percent interest in TDSOI, commenced operations in May 2012. The costs presented above represent 100 percent of TDSOI’s expenditures in the construction of Transocean Honor.

(e) Deepwater Champion, an Ultra-Deepwater drillship, commenced operations in May 2011.

(f) Discoverer India, an Ultra-Deepwater drillship, commenced operations in December 2010.

(g) Discover Luanda, an Ultra-Deepwater drillship, owned through our 65 percent interest in ADDCL, commenced operations in December 2010. The costs presented above represent 100 percent of ADDCL’s expenditures in the construction of Discover Luanda.

(h) Discoverer Inspiration and Dhirubhai Deepwater KG2, two Ultra-Deepwater drillships, commenced operations in March 2010.

Other capital additions—In March 2010, we acquired GSF Explorer, an asset formerly held under capital lease, in exchange for a cash payment in the amount of $15 million, thereby terminating the capital lease obligation. See Note 14—Debt.

Dispositions—During the year ended December 31, 2012, we completed the sales of the Deepwater Floaters Discoverer 534 and Jim Cunningham. In connection with the sales, we received aggregate net cash proceeds of $178 million, and we recognized a net gain on disposal of these drilling units and related equipment in the amount of $51 million ($48 million or $0.13 per diluted share from continuing operations net of tax). In the year ended December 31, 2012, we recognized a net loss on disposal of unrelated assets in the amount of $15 million.

In the year ended December 31, 2011, we recognized an aggregate net loss of $12 million on disposal of assets unrelated to dispositions of rigs.

During the year ended December 31, 2010, we completed the sale of two Midwater Floaters, GSF Arctic II and GSF Arctic IV. In connection with the sale, we received net cash proceeds of $38 million and non-cash proceeds in the form of two notes receivable in the aggregate amount of $165 million (see Note 6—Variable Interest Entities). We operated GSF Arctic IV under a short-term bareboat charter with the new owner of the vessel until November 2010. As a result of the sales, we recognized a net loss on disposal of assets of $15 million ($0.05 per diluted share from continuing operations), which had no tax effect in the year ended December 31, 2010. In the year ended December 31, 2010, we recognized a net gain on disposal of unrelated assets of $5 million.

Loss of drilling unit—On April 22, 2010, the Ultra-Deepwater Floater Deepwater Horizon sank after a blowout of the Macondo well caused a fire and explosion on the rig. In the year ended December 31, 2010, we received $560 million in cash proceeds from insurance recoveries related to the loss of the drilling unit, and we recognized a gain on the loss of the rig of $267 million ($0.83 per diluted share from continuing operations), which had no tax effect. See Note 17—Commitments and Contingencies.

- Definition

The entire disclosure for long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software. This disclosure may include property plant and equipment accounting policies and methodology, a schedule of property, plant and equipment gross, additions, deletions, transfers and other changes, depreciation, depletion and amortization expense, net, accumulated depreciation, depletion and amortization expense and useful lives, income statement disclosures, assets held for sale and public utility disclosures.

+ References+ Details

Goodwill and Other Intangible Assets

12 Months Ended

Dec. 31, 2012

Goodwill and Other Intangible Assets

Goodwill and Other Intangible Assets

Note 13—Goodwill and Other Intangible Assets

Goodwill and other indefinite-lived intangible assets—The gross carrying amounts of goodwill and accumulated impairment associated with our contract drilling services were as follows (in millions):

	Year ended December 31, 2012									Year ended December 31, 2011
	Gross carrying amount			Accumulated impairment			Net carrying amount			Gross carrying amount		Accumulated impairment			Net carrying amount
Balance, beginning of period	$	10,911		$	(7,694	)	$	3,217		$	10,626	$	(2,494	)	$	8,132
Impairment associated with continuing operations	—			(118		)	(118		)	—		(5,200		)	(5,200		)
Reclassified balance associated with discontinued operations (a)	(112		)	—			(112		)	—		—			—
Business combination	—			—			—			285		—			285
Balance, end of period	$	10,799		$	(7,812	)	$	2,987		$	10,911	$	(7,694	)	$	3,217

(a) As a result of our decision to discontinue operations associated with the Standard Jackups and swamp barge components of our contract drilling services operating segment, we allocated $112 million of goodwill attributable to such operations, which was subsequently impaired. See Note 9—Discontinued Operations.

At December 31, 2012 and 2011, goodwill associated with our drilling management services, having a gross carrying amount of $176 million, was fully impaired.

The gross carrying amounts of the ADTI trade name, which we considered to be an indefinite-lived intangible asset attributed to the U.S. operations of our drilling management services segment, and accumulated impairment were as follows (in millions):

	Year ended December 31, 2012									Year ended December 31, 2011
	Gross carrying amount			Accumulated impairment			Net carrying amount			Gross carrying amount		Accumulated impairment			Net carrying amount
Trade name
Balance, beginning of period	$	76		$	(37	)	$	39		$	76	$	(37	)	$	39
Reclassified balance associated with discontinued operations (a)	(76		)	37			(39		)	—		—			—
Balance, end of period	$	—		$	—		$	—		$	76	$	(37	)	$	39

(a) As a result of our decision to discontinue the U.S. operations of our drilling management services operating segment, we reclassified the balances attributable to such operations. See Note 9—Discontinued Operations.

Definite-lived intangible assets and liabilities—The gross carrying amounts of our drilling contract intangibles and drilling management customer relationships, both of which we consider to be definite-lived intangible assets and intangible liabilities, and accumulated amortization and impairment were as follows (in millions):

	Year ended December 31, 2012									Year ended December 31, 2011
	Gross carrying amount			Accumulated amortization and impairment			Net carrying amount			Gross carrying amount		Accumulated amortization and impairment			Net carrying amount
Drilling contract intangible assets
Balance, beginning of period	$	191		$	(191	)	$	—		$	191	$	(185	)	$	6
Amortization	—			—			—			—		(6		)	(6		)
Reclassified balance associated with discontinued operations (a)	(182		)	182			—			—		—			—
Balance, end of period	9			9			—			191		(191		)	—

Customer relationships
Balance, beginning of period	148			(94		)	54			148		(89		)	59
Amortization	—			(1		)	(1		)	—		(5		)	(5		)
Impairment associated with continuing operations	—			(22		)	(22		)	—		—			—
Reclassified balance associated with discontinued operations (b)	(88		)	57			(31		)	—		—			—
Balance, end of period	60			(60		)	—			148		(94		)	54

Total definite-lived intangible assets
Balance, beginning of period	339			(285		)	$	54		339		(274		)	65
Amortization	—			(1		)	(1		)	—		(11		)	(11		)
Impairment associated with continuing operations	—			(22		)	(22		)	—		—			—
Reclassified balance associated with discontinued operations (b)	(270		)	239			(31		)	—		—			—
Balance, end of period	$	69		$	(69	)	$	—		$	339	$	(285	)	$	54

Drilling contract intangible liabilities
Balance, beginning of period	$	1,494		$	(1,393	)	$	101		$	1,494	$	(1,342	)	$	152
Amortization	—			(42		)	(42		)	—		(51		)	(51		)
Reclassified balance associated with discontinued operations (a)	(84		)	84			—			—		—			—
Balance, end of period	$	1,410		$	(1,351	)	$	59		$	1,494	$	(1,393	)	$	101

(a) As a result of our decision to discontinue operations associated with the Standard Jackup and swamp barge asset groups, we reclassified the balances attributable to such operations. See Note 9—Discontinued Operations.

(b) As a result of our decision to discontinue the U.S. operations of our drilling management services operating segment, we reclassified the balances attributable to such operations. See Note 9—Discontinued Operations.

At December 31, 2012, the estimated future amortization of our drilling contract intangible liabilities was as follows (in millions):

	Drilling contract intangible liabilities
Years ending December 31,
2013	$	24
2014	15
2015	14
2016	6
Total intangible liabilities	$	59

- Definition

The entire disclosure for the aggregate amount of goodwill and a description of intangible assets, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets), the carrying amount, the amount of any significant residual value, and the weighted-average amortization period, (b) for intangible assets not subject to amortization (also referred to as indefinite-lived intangible assets), the carrying amount, and (c) the amount of research and development assets acquired and written off in the period, including the line item in the income statement in which the amounts written off are aggregated, if not readily apparent from the income statement. Also discloses (a) for amortizable intangibles assets in total and by major class, the gross carrying amount and accumulated amortization, the total amortization expense for the period, and the estimated aggregate amortization expense for each of the five succeeding fiscal years, (b) for intangible assets not subject to amortization the carrying amount in total and by major class, and (c) for goodwill, in total and for each reportable segment, the changes in the carrying amount of goodwill during the period (including the aggregate amount of goodwill acquired, the aggregate amount of impairment losses recognized, and the amount of goodwill included in the gain (loss) on disposal of a reporting unit). If any part of goodwill has not been allocated to a reportable segment, discloses the unallocated amount and the reasons for not allocating. For each impairment loss recognized related to an intangible asset (excluding goodwill), discloses: (a) a description of the impaired intangible asset and the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method for determining fair value, (c) the caption in the income statement or the statement of activities in which the impairment loss is aggregated, and (d) the segment in which the impaired intangible asset is reported. For each goodwill impairment loss recognized, discloses: (a) a description of the facts and circumstances leading to the impairment, (b) the amount of the impairment loss and the method of determining the fair value of the associated reporting unit, and (c) if a recognized impairment loss is an estimate not finalized and the reasons why the estimate is not final. May also disclose the nature and amount of any significant adjustments made to a previous estimate of an impairment loss.

+ References+ Details

Debt

12 Months Ended

Dec. 31, 2012

Debt

Debt

Note 14—Debt

Debt, net of unamortized discounts, premiums and fair value adjustments, was comprised of the following (in millions):

	December 31, 2012						December 31, 2011
	Transocean Ltd. and subsidiaries		Consolidated variable interest entities		Consolidated total		Transocean Ltd. and subsidiaries		Consolidated variable interest entities		Consolidated total
5% Notes due February 2013	$	250	$	—	$	250	$	253	$	—	$	253
5.25% Senior Notes due March 2013 (a)	502		—		502		507		—		507
TPDI Credit Facilities due March 2015	403		—		403		—		473		473
4.95% Senior Notes due November 2015 (a)	1,118		—		1,118		1,120		—		1,120
Aker Revolving Credit and Term Loan Facility due December 2015	—		—		—		594		—		594
Callable Bonds due February 2016	282		—		282		267		—		267
5.05% Senior Notes due December 2016 (a)	999		—		999		999		—		999
2.5% Senior Notes due October 2017 (a)	748		—		748		—		—		—
ADDCL Credit Facilities due December 2017	—		191		191		—		217		217
Eksportfinans Loans due January 2018	797		—		797		884		—		884
6.00% Senior Notes due March 2018 (a)	998		—		998		998		—		998
7.375% Senior Notes due April 2018 (a)	247		—		247		247		—		247
TPDI Notes due October 2019	—		—		—		—		148		148
6.50% Senior Notes due November 2020 (a)	899		—		899		899		—		899
6.375% Senior Notes due December 2021 (a)	1,199		—		1,199		1,199		—		1,199
3.8% Senior Notes due October 2022 (a)	745		—		745		—		—		—
7.45% Notes due April 2027 (a)	97		—		97		97		—		97
8% Debentures due April 2027 (a)	57		—		57		57		—		57
7% Notes due June 2028	311		—		311		311		—		311
Capital lease contract due August 2029	657		—		657		676		—		676
7.5% Notes due April 2031 (a)	598		—		598		598		—		598
1.50% Series B Convertible Senior Notes due December 2037 (a)	—		—		—		30		—		30
1.50% Series C Convertible Senior Notes due December 2037 (a)	62		—		62		1,663		—		1,663
6.80% Senior Notes due March 2038 (a)	999		—		999		999		—		999
7.35% Senior Notes due December 2041 (a)	300		—		300		300		—		300
Total debt	12,268		191		12,459		12,698		838		13,536
Less debt due within one year
5% Notes due February 2013	250		—		250		—		—		—
5.25% Senior Notes due March 2013 (a)	502		—		502		—		—		—
TPDI Credit Facilities due March 2015	70		—		70		—		70		70
Aker Revolving Credit and Term Loan Facility due December 2015	—		—		—		90		—		90
Callable Bonds due February 2016	282		—		282		—		—		—
ADDCL Credit Facilities due December 2017	—		28		28		—		27		27
Eksportfinans Loans due January 2018	153		—		153		142		—		142
TPDI Notes due October 2019	—		—		—		—		148		148
Capital lease contract due August 2029	20		—		20		17		—		17
1.50% Series B Convertible Senior Notes due December 2037 (a)	—		—		—		30		—		30
1.50% Series C Convertible Senior Notes due December 2037 (a)	62		—		62		1,663		—		1,663
Total debt due within one year	1,339		28		1,367		1,942		245		2,187
Total long-term debt	$	10,929	$	163	$	11,092	$	10,756	$	593	$	11,349

(a) Transocean Inc., a 100 percent owned subsidiary of Transocean Ltd., is the issuer of the notes and debentures, which have been guaranteed by Transocean Ltd. Transocean Ltd. has also guaranteed borrowings under the Five-Year Revolving Credit Facility and the Three-Year Secured Revolving Credit Facility. Transocean Ltd. and Transocean Inc. are not subject to any significant restrictions on their ability to obtain funds from their consolidated subsidiaries by dividends, loans or return of capital distributions. See Note 26—Condensed Consolidating Financial Information.

Scheduled maturities—At December 31, 2012, the scheduled maturities of our debt were as follows (in millions):

	Transocean Ltd. and subsidiaries		Consolidated variable interest entities		Consolidated total
Years ending December 31,
2013	$	1,053	$	28	$	1,081
2014	244		30		274
2015	1,539		61		1,600
2016	1,448		35		1,483
2017	930		37		967
Thereafter	7,032		—		7,032
Total debt, excluding unamortized discounts, premiums and fair value adjustments	12,246		191		12,437
Total unamortized discounts, premiums and fair value adjustments	22		—		22
Total debt	$	12,268	$	191	$	12,459

Five-Year Revolving Credit Facility—We have a $2.0 billion five-year revolving credit facility, established under a bank credit agreement dated November 1, 2011, as amended, that is scheduled to expire on November 1, 2016 (the “Five-Year Revolving Credit Facility”). We may borrow under the Five-Year Revolving Credit Facility at either (1) the adjusted London Interbank Offered Rate (“LIBOR”) plus a margin (the “Five-Year Revolving Credit Facility Margin”) that is based on the credit rating of our non-credit enhanced senior unsecured long-term debt (“Debt Rating”) or (2) the base rate specified in the credit agreement plus the Five-Year Revolving Credit Facility Margin, less one percent per annum. At December 31, 2012, based on our Debt Rating on that date, the Five-Year Revolving Credit Facility Margin was 1.625 percent. Throughout the term of the Five-Year Revolving Credit Facility, we pay a facility fee on the daily unused amount of the underlying commitment, which ranges from 0.125 percent to 0.325 percent depending on our Debt Rating, and was 0.275 percent at December 31, 2012. Among other things, the Five-Year Revolving Credit Facility includes limitations on creating liens, incurring subsidiary debt, transactions with affiliates, sale/leaseback transactions, mergers and the sale of substantially all assets. The Five-Year Revolving Credit Facility also includes a covenant imposing a maximum debt to tangible capitalization ratio of 0.6 to 1.0. Borrowings under the Five-Year Revolving Credit Facility are subject to acceleration upon the occurrence of an event of default. Borrowings are guaranteed by Transocean Ltd. and may be prepaid in whole or in part without premium or penalty. At December 31, 2012, we had $24 million in letters of credit issued and outstanding, we had no borrowings outstanding, and we had $2.0 billion of available borrowing capacity under the Five-Year Revolving Credit Facility.

Three-Year Secured Revolving Credit Facility—We have a $900 million three-year secured revolving credit facility, established under a bank credit agreement dated October 25, 2012, that is scheduled to expire on October 25, 2015 (the “Three-Year Secured Revolving Credit Facility”). We may borrow under the Three-Year Secured Revolving Credit Facility at either (1) LIBOR plus a margin (the “Three-Year Secured Revolving Credit Facility Margin”) that ranges from 0.875 percent to 2.5 percent based on our Debt Rating or (2) the base rate specified in the credit agreement plus the Three-Year Secured Revolving Credit Facility Margin, less one percent per annum. At December 31, 2012, based on our Debt Rating on that date, the Three-Year Secured Revolving Credit Facility Margin was 2.0 percent. Throughout the term of the Three-Year Secured Revolving Credit Facility, we pay a facility fee on the daily unused amount of the underlying commitment, which ranges from 0.125 percent to 0.50 percent depending on our Debt Rating, and was 0.375 percent at December 31, 2012. Among other things, the Three-Year Secured Revolving Credit Facility includes limitations on creating liens, incurring subsidiary debt, transactions with affiliates, sale/leaseback transactions, mergers and the sale of substantially all assets. The Three-Year Secured Revolving Credit Facility also contains a covenant imposing a maximum debt to tangible capitalization ratio of 0.6 to 1.0. Borrowings under the Three-Year Secured Revolving Credit Facility are subject to acceleration upon the occurrence of an event of default. Borrowings are guaranteed by Transocean Ltd. and Transocean Inc. and may be prepaid in whole or in part without premium or penalty. At December 31, 2012, we had no borrowings outstanding, and we had $900 million of available borrowing capacity under the Three-Year Secured Revolving Credit Facility.

Borrowings under the Three-Year Secured Revolving Credit Facility are secured by the Ultra-Deepwater Floaters Deepwater Champion, Discoverer Americas and Discoverer Inspiration. At December 31, 2012 and 2011, the aggregate carrying amount of Deepwater Champion, Discoverer Americas and Discoverer Inspiration was $2.3 billion.

5% Notes and 7% Notes—Two of our wholly-owned subsidiaries are the obligors on the 5% Notes due 2013 (the “5% Notes”) and the 7% Notes due 2028 (the “7% Notes”), and we have not guaranteed either obligation. The indentures related to the 5% Notes and the 7% Notes contain limitations on creating liens and sale/leaseback transactions. The respective obligor may redeem the 5% Notes and the 7% Notes in whole or in part at a price equal to 100 percent of the principal amount plus accrued and unpaid interest, if any, and a make-whole premium. At December 31, 2012, the aggregate outstanding principal amount of the 5% Notes and the 7% Notes was $250 million and $300 million, respectively. See Note 15—Derivatives and Hedging and Note 29—Subsequent Events.

5.25% Senior Notes, 6.00% Senior Notes and 6.80% Senior Notes—In December 2007, we issued $500 million aggregate principal amount of 5.25% Senior Notes due March 2013 (the “5.25% Senior Notes”), $1.0 billion aggregate principal amount of 6.00% Senior Notes due March 2018 (the “6.00% Senior Notes”) and $1.0 billion aggregate principal amount of 6.80% Senior Notes due March 2038 (the “6.80% Senior Notes”). The indenture pursuant to which the notes were issued contains restrictions on creating liens, engaging in sale/leaseback transactions and engaging in merger, consolidation or reorganization transactions. We may redeem some or all of the notes at any time, at a redemption price equal to 100 percent of the principal amount plus accrued and unpaid interest, if any, and a make-whole premium. At December 31, 2012, the aggregate outstanding principal amount of the 5.25% Senior Notes, the 6.00% Senior Notes and the 6.80% Senior Notes was $500 million, $1.0 billion and $1.0 billion, respectively, were outstanding. See Note 15—Derivatives and Hedging.

TPDI Credit Facilities—We have a $1.265 billion secured credit facility, comprised of a $1.0 billion senior term loan, a $190 million junior term loan and a $75 million revolving credit facility, established under a bank credit agreement dated October 28, 2008, that is scheduled to expire in March 2015 (the “TPDI Credit Facilities”). One of our subsidiaries participates in the senior and junior term loans with an aggregate commitment of $595 million. The senior term loan, the junior term loan and the revolving credit facility bear interest at LIBOR plus the applicable margins of 1.45 percent, 2.25 percent and 1.45 percent, respectively. The senior term loan requires quarterly payments with a final payment in March 2015. The junior term loan and the revolving credit facility are due in full in March 2015. The TPDI Credit Facilities have covenants that require TPDI to maintain a minimum cash balance and available liquidity, a minimum debt service ratio and a maximum leverage ratio. The TPDI Credit Facilities may be prepaid in whole or in part without premium or penalty. At December 31, 2012, outstanding borrowings under the TPDI Credit Facilities were $805 million, of which $402 million was due to one of our subsidiaries and was eliminated in consolidation. The weighted-average interest rate on December 31, 2012 was 1.9 percent. See Note 15—Derivatives and Hedging.

Borrowings under the TPDI Credit Facilities are secured by the Ultra-Deepwater Floaters Dhirubhai Deepwater KG1 and Dhirubhai Deepwater KG2. At December 31, 2012 and 2011, the aggregate carrying amount of Dhirubhai Deepwater KG1 and Dhirubhai Deepwater KG2 was $1.4 billion.

Under the TPDI Credit Facilities, we are required to satisfy certain liquidity requirements, including a requirement to maintain certain cash balances in restricted accounts for the payment of scheduled installments. At December 31, 2012 and 2011, we had restricted cash investments of $23 million. At December 31, 2012 and 2011, we had an outstanding letter of credit in the amount of $60 million to satisfy additional liquidity requirements under the TPDI Credit Facilities.

4.95% Senior Notes and 6.50% Senior Notes—In September 2010, we issued $1.1 billion aggregate principal amount of 4.95% Senior Notes due November 2015 (the “4.95% Senior Notes”) and $900 million aggregate principal amount of 6.50% Senior Notes due November 2020 (the “6.50% Senior Notes,” and together with the 4.95% Senior Notes, the “2010 Senior Notes”). We are required to pay interest on the 2010 Senior Notes on May 15 and November 15 of each year, beginning November 15, 2010. We may redeem some or all of the 2010 Senior Notes at any time at a redemption price equal to 100 percent of the principal amount plus accrued and unpaid interest, if any, and a make whole premium. The indenture pursuant to which the 2010 Senior Notes were issued contains restrictions on creating liens, engaging in sale/leaseback transactions and engaging in merger, consolidation or reorganization transactions. At December 31, 2012, the aggregate outstanding principal amount of the 4.95% Senior Notes and the 6.50% Senior Notes was $1.1 billion and $900 million, respectively. See Note 15—Derivatives and Hedging.

5.05% Senior Notes, 6.375% Senior Notes and 7.35% Senior Notes—In December 2011, we issued $1.0 billion aggregate principal amount of 5.05% Senior Notes due December 2016 (the “5.05% Senior Notes”), $1.2 billion aggregate principal amount of 6.375% Senior Notes due December 2021 (the “6.375% Senior Notes”) and $300 million aggregate principal amount of 7.35% Senior Notes due December 2041 (the “7.35% Senior Notes,” and collectively with the 5.05% Senior Notes and the 6.375% Senior Notes, the “2011 Senior Notes”). The interest rates for the notes are subject to adjustment from time to time upon a change to our Debt Rating. The indenture pursuant to which the 2011 Senior Notes were issued contains restrictions on creating liens, engaging in sale/leaseback transactions and engaging in merger, consolidation or reorganization transactions. We may redeem some or all of the 2011 Senior Notes at any time at a redemption price equal to 100 percent of the principal amount plus accrued and unpaid interest, if any, and a make whole premium. At December 31, 2012, the aggregate outstanding principal amount of the 5.05% Senior Notes, the 6.375% Senior Notes and the 7.35% Senior Notes was $1.0 billion, $1.2 billion and $300 million, respectively.

Aker Revolving Credit and Term Loan Facility—We had a credit facility, comprised of a $500 million revolving credit facility and a $400 million term loan, established under the Revolving Credit and Term Loan Facility Agreement dated February 21, 2011 (the “Aker Revolving Credit and Term Loan Facility”). In the year ended December 31, 2012, we prepaid $333 million of borrowings under the Aker Term Loan, and we recognized an aggregate gain of $2 million on the retirement of debt. In September 2012, we cancelled the Aker Revolving Credit and Term Loan Facility.

Callable Bonds—In connection with our acquisition of Aker Drilling, we assumed NOK 940 million aggregate principal amount of the FRN Aker Drilling ASA Senior Unsecured Callable Bond Issue 2011/2016 (the “FRN Callable Bonds”) and NOK 560 million aggregate principal amount of the 11% Aker Drilling ASA Senior Unsecured Callable Bond Issue 2011/2016 (the “11% Callable Bonds,” and together with the FRN Callable Bonds, the “Callable Bonds”), which are publicly traded on the Oslo Stock Exchange. The FRN Callable Bonds bear interest at the Norwegian Interbank Offered Rate plus seven percent. The Callable Bonds require quarterly interest payments and may be redeemed in whole or in part at an amount equal to the outstanding principal plus a certain premium amount and accrued unpaid interest. At December 31, 2012, the total aggregate principal amounts of the FRN Callable Bonds and the 11% Callable Bonds were NOK 940 million and NOK 560 million, equivalent to $169 million and $101 million, respectively, using an exchange rate of NOK 5.56 to US $1.00. At December 31, 2012, the interest rate on the FRN Callable Bonds was 9.0 percent. See Note 15—Derivatives and Hedging and Note 29—Subsequent Events.

2.5% Senior Notes and 3.8% Senior Notes—In September 2012, we issued $750 million aggregate principal amount of 2.5% Senior Notes due October 2017 (the “2.5% Senior Notes”) and $750 million aggregate principal amount of 3.8% Senior Notes due October 2022 (the “3.8% Senior Notes,” and together with the 2.5% Senior Notes, the “2012 Senior Notes”). The interest rates for the notes are subject to adjustment from time to time upon a change to our Debt Rating. The indenture pursuant to which the 2012 Senior Notes were issued contains restrictions on creating liens, engaging in sale/leaseback transactions and engaging in merger, consolidation or reorganization transactions. We may redeem some or all of the 2012 Senior Notes at any time prior to maturity at a redemption price equal to 100 percent of the principal amount plus accrued and unpaid interest, if any, together with a make-whole premium unless, in the case of the 3.8% Senior Notes, such redemption occurs on or after July 15, 2022, in which case no such make-whole premium will apply. At December 31, 2012, the aggregate outstanding principal amount of the 2.5% Senior Notes and the 3.8% Senior Notes was $750 million and $750 million, respectively.

ADDCL Credit Facilities—ADDCL has a senior secured credit facility, comprised of Tranche A for $215 million and Tranche C for $399 million, under a bank credit agreement dated June 2, 2008 that is scheduled to expire in December 2017 (the “ADDCL Primary Loan Facility”). Unaffiliated financial institutions provide the commitment for and borrowings under Tranche A, and one of our subsidiaries provides the commitment for Tranche C. Tranche A bears interest at LIBOR plus the applicable margin of 0.725 percent. Tranche A requires semi-annual installments of principal and interest. The ADDCL Primary Loan Facility contains covenants that require ADDCL to maintain certain cash balances to service the debt and also limits ADDCL’s ability to incur additional indebtedness, to acquire assets, or to make distributions or other payments. At December 31, 2012, $163 million was outstanding under Tranche A at a weighted-average interest rate of 1.2 percent. At December 31, 2012, $399 million was outstanding under Tranche C, which was eliminated in consolidation.

Borrowings under the ADDCL Primary Loan Facility are secured by the Ultra-Deepwater Floater Discoverer Luanda. At December 31, 2012 and 2011, the carrying amount of Discoverer Luanda was $786 million and $796 million, respectively.

ADDCL also has a $90 million secondary credit facility, established under a bank credit agreement dated June 2, 2008 that is scheduled to expire in December 2015 (the “ADDCL Secondary Loan Facility” and together with the ADDCL Primary Loan Facility, the “ADDCL Credit Facilities”). One of our subsidiaries provides 65 percent of the total commitment under the ADDCL Secondary Loan Facility. The facility bears interest at LIBOR plus the applicable margin, ranging from 3.125 percent to 5.125 percent, depending on certain milestones. Borrowings under the ADDCL Secondary Loan Facility are subject to acceleration by the unaffiliated financial institution upon the occurrence of certain events of default, including if our Debt Rating falls below investment grade. The ADDCL Secondary Loan Facility is payable in full in December 2015, and it may be prepaid in whole or in part without premium or penalty. At December 31, 2012, $80 million was outstanding under the ADDCL Secondary Loan Facility, of which $52 million was provided by one of our subsidiaries and has been eliminated in consolidation. The weighted-average interest rate on December 31, 2012 was 3.4 percent.

ADDCL is required to maintain certain cash balances in restricted accounts for the payment of the scheduled installments on the ADDCL Credit Facilities. At December 31, 2012 and 2011, ADDCL had restricted cash investments of $19 million and $16 million, respectively.

Eksportfinans Loans—In connection with our acquisition of Aker Drilling, we assumed the borrowings outstanding under the Loan Agreement dated September 12, 2008 (“Eksportfinans Loan A”) and under the Loan Agreement dated November 18, 2008 (“Eksportfinans Loan B,” and together with Eksportfinans Loan A, the “Eksportfinans Loans”). The Eksportfinans Loans bear interest at a fixed rate of 4.15 percent and require semi-annual installments of principal and interest through September 2017 and January 2018 for Eksportfinans Loan A and Eksportfinans Loan B, respectively. At December 31, 2012, $381 million and $420 million principal amount were outstanding under Eksportfinans Loan A and Eksportfinans Loan B, respectively.

The Eksportfinans Loans require cash collateral to remain on deposit at a financial institution through expiration (the “Aker Restricted Cash Investments”). The Aker Restricted Cash Investments bear interest at a fixed rate of 4.15 percent with semi-annual installments that correspond with those of the Eksportfinans Loans. At December 31, 2012 and 2011, the aggregate principal amount of the Aker Restricted Cash Investments was $801 million and $889 million, respectively.

7.375% Senior Notes—In March 2002, we issued $247 million principal amount of our 7.375% Senior Notes due April 2018 (the “7.375% Senior Notes”). The indenture pursuant to which the 7.375% Senior Notes were issued contains restrictions on creating liens, engaging in sale/leaseback transactions and engaging in merger, consolidation or reorganization transactions. At December 31, 2012, the aggregate outstanding principal amount of the 7.375% Senior Notes was $246 million.

TPDI Notes—We previously issued promissory notes (the “TPDI Notes”), which were payable to one of our subsidiaries and TPDI’s former other shareholder, Quantum Pacific Management Limited (“Quantum”), and had maturities through October 2019. On May 31, 2012, in connection with the exchange of Quantum’s interest in TPDI for our shares, the TPDI Notes payable to Quantum were extinguished and contributed as additional paid-in capital. See Note 18—Redeemable Noncontrolling Interest.

7.45% Notes and 8% Debentures—In April 1997, a predecessor of Transocean Inc. issued $100 million aggregate principal amount of 7.45% Notes due April 2027 (the “7.45% Notes”) and $200 million aggregate principal amount of 8% Debentures due April 2027 (the “8% Debentures”). The indenture pursuant to which the 7.45% Notes and the 8% Debentures were issued contains restrictions on creating liens, engaging in sale/leaseback transactions and engaging in merger, consolidation or reorganization transactions. The 7.45% Notes and the 8% Debentures are redeemable at any time at our option subject to a make-whole premium. At December 31, 2012, the aggregate outstanding principal amount of the 7.45% Notes and the 8% Debentures was $100 million and $57 million, respectively.

Capital lease contract—In August 2009, we accepted delivery of Petrobras 10000, an asset held under capital lease, and we recorded $716 million to property and equipment, net and a corresponding increase to long-term debt. The capital lease contract has an implicit interest rate of 7.8 percent and requires scheduled monthly payments of $6 million through August 2029, after which we will have the right and obligation to acquire the drillship from the lessor for one dollar. See Note 12—Drilling Fleet and Note 17—Commitments and Contingencies.

7.5% Notes—In April 2001, we issued $600 million aggregate principal amount of 7.5% Notes due April 2031 (the “7.5% Notes”). The indenture pursuant to which the notes were issued contains restrictions on creating liens, engaging in sale/leaseback transactions and engaging in merger, consolidation or reorganization transactions. At December 31, 2012, the aggregate outstanding principal amount of the 7.5% Notes was $600 million.

1.625% Series A, 1.50% Series B and 1.50% Series C Convertible Senior Notes—In December 2007, we issued $2.2 billion aggregate principal amount of 1.625% Series A Convertible Senior Notes due December 2037 (the “Series A Convertible Senior Notes”), $2.2 billion aggregate principal amount of 1.50% Series B Convertible Senior Notes due December 2037 (the “Series B Convertible Senior Notes”) and $2.2 billion aggregate principal amount of 1.50% Series C Convertible Senior Notes due December 2037 (the “Series C Convertible Senior Notes,” and together with the Series A Convertible Senior Notes and Series B Convertible Senior Notes, the “Convertible Senior Notes”). At December 31, 2012, the Series C Convertible Senior Notes could be converted under the circumstances specified below at a rate of 6.2905 shares per $1,000 note, equivalent to a conversion price of $158.97 per share, subject to adjustments upon the occurrence of certain events. Upon conversion, we were required to deliver, in lieu of shares, cash up to the aggregate principal amount of notes to be converted and shares in respect of the remainder, if any, of our conversion obligation.

Holders could convert their notes only under the following circumstances: (1) during any calendar quarter if the last reported sale price of our shares for at least 20 trading days in a period of 30 consecutive trading days ending on the last trading day of the preceding calendar quarter is more than 130 percent of the conversion price, (2) during the five business days after the average trading price per $1,000 principal amount of the notes is equal to or less than 98 percent of the average conversion value of such notes during the preceding five trading-day period as described herein, (3) during specified periods if specified distributions to holders of our shares are made or specified corporate transactions occur, (4) prior to the close of business on the business day preceding the redemption date if the notes are called for redemption or (5) on or after September 15, 2037 and prior to the close of business on the business day prior to the stated maturity of the notes. As of December 31, 2012, no shares were issuable upon conversion of any series of the Convertible Senior Notes since none of the circumstances giving rise to potential conversion were present.

We could redeem some or all of the Series C Convertible Senior Notes at any time after December 20, 2012 at a redemption price equal to 100 percent of the principal amount plus accrued and unpaid interest, if any. Holders of the Series C Convertible Senior Notes had the right to require us to repurchase their notes on December 15, 2017, December 15, 2022, December 15, 2027 and December 15, 2032, and upon the occurrence of a fundamental change, at a repurchase price in cash equal to 100 percent of the principal amount of the notes to be repurchased plus accrued and unpaid interest, if any.

The carrying amounts of the liability components of the outstanding Convertible Senior Notes were as follows (in millions):

	December 31, 2012						December 31, 2011
	Principal amount		Unamortized discount		Carrying amount		Principal amount		Unamortized discount			Carrying amount
Carrying amount of liability component
Series B Convertible Senior Notes due 2037	$	—	$	—	$	—	$	30	$	—		$	30
Series C Convertible Senior Notes due 2037	62		—		62		1,722		(59		)	1,663

The carrying amounts of the equity components of the outstanding Convertible Senior Notes were as follows (in millions):

	December 31,
	2012		2011
Carrying amount of equity component
Series B Convertible Senior Notes due 2037	$	—	$	4
Series C Convertible Senior Notes due 2037	10		276

Including the amortization of the unamortized discount, the effective interest rate for the Series C Convertible Senior Notes was 5.28 percent. At December 31, 2012, the remaining period over which the discount will be amortized is less than one year for the Series C Convertible Senior Notes. Interest expense, excluding amortization of debt issue costs, was as follows (in millions):

	Years ended December 31,
	2012		2011		2010
Interest expense
Series A Convertible Senior Notes due 2037	$	—	$	—	$	58
Series B Convertible Senior Notes due 2037	—		78		98
Series C Convertible Senior Notes due 2037	84		84		98

On December 14, 2012, holders of the Series C Convertible Senior Notes had the option to require us to repurchase all or any part of such holders’ notes. As a result, we were required to repurchase an aggregate principal amount of $1.7 billion of the Series C Convertible Senior Notes for an aggregate cash payment of $1.7 billion. See Note 29—Subsequent Events.

On December 15, 2011, holders of the Series B Convertible Senior Notes had the option to require us to repurchase all or any part of such holders’ notes. As a result, we were required to repurchase an aggregate principal amount of $1.7 billion of the Series B Convertible Senior Notes for an aggregate cash payment of $1.7 billion. In February 2012, we redeemed the remaining $30 million aggregate principal amount of the Series B Convertible Senior Notes for an aggregate cash payment of $30 million.

On December 15, 2010, holders of the Series A Convertible Senior Notes had the option to require us to repurchase all or any part of such holders’ notes. As a result, we were required to repurchase an aggregate principal amount of $1.3 billion of the Series A Convertible Senior Notes for an aggregate cash payment of $1.3 billion. In January 2011, we redeemed the remaining $11 million aggregate principal amount of the Series A Convertible Senior Notes for an aggregate cash payment of $11 million.

During the year ended December 31, 2010, we repurchased an aggregate principal amount of $478 million of the Series C Convertible Senior Notes for an aggregate cash payment of $453 million. In connection with the repurchases, we recognized a loss on retirement of $21 million ($0.07 per diluted share), with no tax effect, associated with the debt components of the repurchased notes, and we recorded additional paid-in capital of $8 million associated with the equity components of the repurchased notes.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References+ Details

Derivatives and Hedging

12 Months Ended

Dec. 31, 2012

Derivatives and Hedging

Derivatives and Hedging

Note 15—Derivatives and Hedging

Derivatives designated as hedging instruments—We have interest rate swaps, which are designated and have qualified as fair value hedges, to reduce our exposure to changes in the fair values of the 5% Notes due February 2013 and the 5.25% Senior Notes due March 2013. The interest rate swaps have aggregate notional amounts equal to the corresponding face values of the hedged instruments and have stated maturities that coincide with those of the hedged instruments. We have determined that the hedging relationships qualify for, and we have applied, the shortcut method of accounting, under which the interest rate swaps are considered to have no ineffectiveness and no ongoing assessment of effectiveness is required. Accordingly, changes in the fair value of the interest rate swaps recognized in interest expense offset changes in the fair value of the hedged fixed-rate notes. Through the stated maturities of the interest rate swaps in February and March 2013, we receive semi-annual interest at a fixed rate equal to that of the underlying debt instrument and pay variable interest semi-annually at three-month LIBOR plus a margin.

We previously entered into interest rate swaps, which were designated and qualified as a fair value hedge, to reduce our exposure to changes in the fair values of the 4.95% Senior Notes due November 2015. In June 2012, we terminated these interest rate swaps and received an aggregate net cash payment of $23 million in the year ended December 31, 2012.

We have interest rate swaps, which have been designated and qualify as a cash flow hedge, to reduce the variability of cash interest payments associated with the variable-rate borrowings under the TPDI Credit Facilities through December 31, 2014. The aggregate notional amount corresponds with the aggregate outstanding amount of the borrowings under the TPDI Credit Facilities.

We have cross-currency interest rate swaps, which have been designated and qualify as a cash flow hedge, to reduce the variability of cash interest payments and the final principal payment due at maturity in February 2016 associated with the changes in the U.S. dollar to Norwegian krone exchange rate. The aggregate notional amount corresponds with the aggregate outstanding amount of the 11% Callable Bonds. Our obligations under the swap agreements are secured by the Ultra-Deepwater Floaters Transocean Spitsbergen and Transocean Barents. At December 31, 2012 and 2011, the aggregate carrying amount of Transocean Spitsbergen and Transocean Barents was $1.5 billion.

At December 31, 2012, the aggregate notional amounts and the weighted average interest rates associated with our derivatives designated as hedging instruments were as follows (in millions, except weighted average interest rates):

	Pay					Receive
	Aggregate notional amount		Fixed or variable rate	Weighted average rate		Aggregate notional amount			Fixed or variable rate	Weighted average rate
Interest rate swaps, fair value hedges	$	750	variable	3.5	%	$	750		fixed	5.2	%
Interest rate swaps, cash flow hedges	$	385	fixed	2.4	%	$	385		variable	0.3	%
Cross-currency swaps, cash flow hedges	$	102	fixed	8.9	%	NOK		560	fixed	11.0	%

The effect on our consolidated statements of operations resulting from derivatives designated as cash flow hedges was as follows (in millions):

		Years ended December 31,
	Statement of operations classification	2012			2011			2010
Loss associated with effective portion	Interest expense, net of amounts capitalized	$	(5	)	$	(11	)	$	(12	)
Gain associated with effective portion	Other, net	6			—			—

The balance sheet classification and aggregate carrying amount of our derivatives designated as hedging instruments, measured at fair value, were as follows (in millions):

		December 31,
	Balance sheet classification	2012		2011
Interest rate swaps, fair value hedges	Other current assets	$	6	$	5
Interest rate swaps, fair value hedges	Other assets	—		31
Interest rate swaps, cash flow hedges	Other long-term liabilities	13		16
Cross-currency swaps, cash flow hedges	Other current assets	1		—
Cross-currency swaps, cash flow hedges	Other assets	1		—
Cross-currency swaps, cash flow hedges	Other long-term liabilities	—		7

Derivatives not designated as hedging instruments—In connection with our acquisition of Aker Drilling, we assumed certain derivatives not designated as hedging instruments. In the years ended December 31, 2012 and 2011, we terminated certain of these interest rate swaps not designated as hedging instruments and made aggregate cash payments of $14 million and $15 million, respectively.

Additionally, in August 2011, in connection with our acquisition of Aker Drilling, we entered into a forward exchange contract, which was not designated and did not qualify as a hedging instrument for accounting purposes, in order to offset the variability in the cash flows resulting from fluctuations in the U.S. dollar to Norwegian krone exchange rate. The forward exchange contract had aggregate notional amounts requiring us to pay $1.1 billion in exchange for receiving NOK 6.1 billion, representing an exchange rate of $1.00 to NOK 5.40. On September 28, 2011, we settled the full amount of the forward exchange contract and made a cash payment of $78 million.

In connection with our sale transactions with Shelf Drilling, we received non-cash proceeds in the form of preference shares with a liquidation value of $195 million. The preference shares contain two embedded derivatives, which are not designated and do not qualify as hedging instruments for accounting purposes, including (a) a ceiling dividend rate indexed to the price of Brent Crude oil and (b) a dividend rate premium triggered in the event of credit default. See Note 9—Discontinued Operations.

The effect on our consolidated statements of operations resulting from changes in the fair values of derivatives not designated as hedging instruments was as follows (in millions):

		Years ended December 31,
	Statement of operations classification	2012			2011			2010
Loss associated with undesignated interest rate swaps	Interest expense, net of amounts capitalized	$	(1	)	$	—		$	—
Loss associated with undesignated forward exchange contract	Other, net	—			(78		)	—

The balance sheet classification and aggregate carrying amount of our derivatives not designated as hedging instruments, measured at fair value, were as follows (in millions):

		December 31,
	Balance sheet classification	2012		2011
Interest rate swaps not designated as hedging instruments	Other long-term liabilities	$	—	$	15
Embedded derivatives not designated as hedging instruments	Other long-term liabilities	2		—

- Definition

The entire disclosure for the entity's entire derivative instruments and hedging activities. Describes an entity's risk management strategies, derivatives in hedging activities and non-hedging derivative instruments, the assets, obligations, liabilities, revenues and expenses arising therefrom, and the amounts of and methodologies and assumptions used in determining the amounts of such items.

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+ Details

Postemployment Benefit Plans

12 Months Ended

Dec. 31, 2012

Postemployment Benefit Plans

Postemployment Benefit Plans

Note 16—Postemployment Benefit Plans

Defined benefit pension plans and other postretirement employee benefit plans

Overview—We maintain a single qualified defined benefit pension plan in the U.S. (the “U.S. Plan”) covering substantially all U.S. employees. We also maintain a funded supplemental benefit plan (the “Supplemental Plan”) that offers benefits to certain employees that are ineligible for benefits under the U.S. Plan and two unfunded supplemental benefit plans (the “Other Supplemental Plans”) that provide certain eligible employees with benefits in excess of those allowed under the U.S. Plan. Additionally, we maintain two funded and two unfunded defined benefit plans (collectively, the “Frozen Plans”) that we assumed in connection with our mergers with GlobalSantaFe and R&B Falcon Corporation, all of which were frozen prior to the respective mergers and for which benefits no longer accrue but the pension obligations have not been fully distributed. We refer to the U.S. Plan, the Supplemental Plan, the Other Supplemental Plans and the Frozen Plans, collectively, as the “U.S. Plans.”

We maintain a defined benefit plan in the U.K. (the “U.K. Plan”) covering certain current and former employees in the U.K. We also provide seven funded defined benefit plans, primarily group pension schemes with life insurance companies, three of which we assumed in connection with our acquisition of Aker Drilling, and two unfunded plans covering our eligible Norway employees and former employees (the “Norway Plans”). We also maintain unfunded defined benefit plans (the “Other Plans”) that provide retirement and severance benefits for certain of our Indonesian, Nigerian and Egyptian employees. We refer to the U.K. Plan, the Norway Plans and the Other Plans, collectively, as the “Non-U.S. Plans.”

We refer to the U.S. Plans and the Non-U.S. Plans, collectively, as the “Transocean Plans”. Additionally, we have several unfunded contributory and noncontributory other postretirement employee benefit plans (the “OPEB Plans”) covering substantially all of our U.S. employees.

Assumptions—The following were the weighted-average assumptions used to determine benefit obligations:

	December 31, 2012						December 31, 2011
	U.S. Plans		Non-U.S. Plans		OPEB Plans		U.S. Plans		Non-U.S. Plans		OPEB Plans
Discount rate	4.19	%	5.37	%	3.63	%	4.66	%	4.90	%	4.28	%
Compensation trend rate	4.21	%	4.38	%	n/a		4.22	%	4.30	%	n/a

The following were the weighted-average assumptions used to determine net periodic benefit costs:

	Year ended December 31, 2012						Year ended December 31, 2011						Year ended December 31, 2010
	U.S. Plans		Non-U.S. Plans		OPEB Plans		U.S. Plans		Non-U.S. Plans		OPEB Plans		U.S. Plans		Non-U.S. Plans		OPEB Plans
Discount rate	4.67	%	5.43	%	4.27	%	5.49	%	5.73	%	4.94	%	5.86	%	5.67	%	5.51	%
Expected rate of return	7.47	%	6.07	%	n/a		8.49	%	6.42	%	n/a		8.49	%	6.65	%	n/a
Compensation trend rate	4.22	%	4.61	%	n/a		4.24	%	4.62	%	n/a		4.21	%	4.77	%	n/a
Health care cost trend rate
-initial	n/a		n/a		8.08	%	n/a		n/a		8.08	%	n/a		n/a		8.00	%
-ultimate	n/a		n/a		5.00	%	n/a		n/a		5.00	%	n/a		n/a		5.00	%
-ultimate year	n/a		n/a		2019		n/a		n/a		2018		n/a		n/a		2016

“n/a” means not applicable.

Funded status—The changes in projected benefit obligation, plan assets and funded status and the amounts recognized on our consolidated balance sheets were as follows (in millions):

	Year ended December 31, 2012												Year ended December 31, 2011
	U.S. Plans			Non-U.S. Plans			OPEB Plans			Total			U.S. Plans			Non-U.S. Plans			OPEB Plans			Total
Change in projected benefit obligation
Projected benefit obligation, beginning of period	$	1,260		$	447		$	53		$	1,760		$	1,068		$	374		$	56		$	1,498
Assumed projected benefit obligation	—			—			—			—			—			17			—			17
Actuarial (gains) losses, net	128			(15		)	4			117			128			24			(3		)	149
Service cost	49			31			1			81			43			21			1			65
Interest cost	59			24			2			85			58			22			3			83
Foreign currency exchange rate	—			19			—			19			—			(1		)	—			(1		)
Benefits paid	(45		)	(23		)	(3		)	(71		)	(37		)	(12		)	(5		)	(54		)
Participant contributions	—			2			1			3			—			2			1			3
Special termination benefits	1			—			—			1			—			—			—			—
Settlements and curtailments	—			14			—			14			—			—			—			—
Projected benefit obligation, end of period	1,452			499			58			2,009			1,260			447			53			1,760

Change in plan assets
Fair value of plan assets, beginning of period	769			351			—			1,120			697			332			—			1,029
Fair value of acquired plan assets	—			—			—			—			—			9			—			9
Actual return on plan assets	116			28			—			144			39			(8		)	—			31
Foreign currency exchange rate changes	—			15			—			15			—			2			—			2
Employer contributions	108			49			2			159			70			29			4			103
Participant contributions	—			2			1			3			—			2			1			3
Benefits paid	(45		)	(23		)	(3		)	(71		)	(37		)	(12		)	(5		)	(54		)
Settlement and curtailments	—			—			—			—			—			(3		)	—			(3		)
Fair value of plan assets, end of period	948			422			—			1,370			769			351			—			1,120

Funded status, end of period	$	(504	)	$	(77	)	$	(58	)	$	(639	)	$	(491	)	$	(96	)	$	(53	)	$	(640	)

Balance sheet classification, end of period:
Pension asset, non-current	$	—		$	3		$	—		$	3		$	—		$	—		$	—		$	—
Accrued pension liability, current	3			24			3			30			3			5			3			11
Accrued pension liability, non-current	501			56			55			612			488			91			50			629
Accumulated other comprehensive income (loss) (a)	(469		)	(80		)	(6		)	(555		)	(437		)	(111		)	(2		)	(550		)

(a) Amounts are before income tax effect.

The aggregate projected benefit obligation and fair value of plan assets for plans with a projected benefit obligation in excess of plan assets were as follows (in millions):

	December 31, 2012								December 31, 2011
	U.S. Plans		Non-U.S. Plans		OPEB Plans		Total		U.S. Plans		Non-U.S. Plans		OPEB Plans		Total
Projected benefit obligation	$	1,452	$	482	$	58	$	1,992	$	1,260	$	447	$	53	$	1,760
Fair value of plan assets	948		404		—		1,352		769		351		—		1,120

The accumulated benefit obligation for all defined benefit pension plans was $1.7 billion and $1.5 billion at December 31, 2012 and 2011, respectively. The aggregate accumulated benefit obligation and fair value of plan assets for plans with an accumulated benefit obligation in excess of plan assets were as follows (in millions):

	December 31, 2012								December 31, 2011
	U.S. Plans		Non-U.S. Plans		OPEB Plans		Total		U.S. Plans		Non-U.S. Plans		OPEB Plans		Total
Accumulated benefit obligation	$	1,255	$	335	$	58	$	1,648	$	1,083	$	288	$	53	$	1,424
Fair value of plan assets	948		298		—		1,246		769		254		—		1,023

Plan assets—We periodically review our investment policies, plan assets and asset allocation strategies to evaluate performance relative to specified objectives. In determining our asset allocation strategies for the U.S. Plans, we review the results of regression models to assess the most appropriate target allocation for each plan, given the plan’s status, demographics and duration. For the U.K. Plans, the plan trustees establish the asset allocation strategies consistent with the regulations of the U.K. pension regulators and in consultation with financial advisors and company representatives. Investment managers for the U.S. Plans and the U.K. Plan are given established ranges within which the investments may deviate from the target allocations. For the Norway Plans, we establish minimum rates of return under the terms of investment contracts with insurance companies.

As of December 31, 2012 and 2011, the weighted-average target and actual allocations of the investments for our funded Transocean Plans were as follows:

					Actual allocation at December 31,
	Target allocation				2012				2011
	U.S. Plans		Non-U.S. Plans		U.S. Plans		Non-U.S. Plans		U.S. Plans		Non-U.S. Plans
Equity securities	65	%	49	%	64	%	49	%	64	%	47	%
Fixed income securities	35	%	14	%	36	%	17	%	36	%	12	%
Other investments	—		37	%	—		34	%	—		41	%
Total	100	%	100	%	100	%	100	%	100	%	100	%

As of December 31, 2012, the investments for our funded Transocean Plans were categorized as follows (in millions):

	December 31, 2012
	Significant observable inputs						Significant other observable inputs						Total
	U.S. Plans		Non-U.S. Plans		Transocean Plans		U.S. Plans		Non-U.S. Plans		Transocean Plans		U.S. Plans		Non-U.S. Plans		Transocean Plans
Mutual funds
U.S. equity funds	$	525	$	—	$	525	$	—	$	32	$	32	$	525	$	32	$	557
Non-U.S. equity funds	120		—		120		3		176		179		123		176		299
Bond funds	296		—		296		—		73		73		296		73		369
Total mutual funds	941		—		941		3		281		284		944		281		1,225

Other investments
Cash and money market funds	4		2		6		—		6		6		4		8		12
Property collective trusts	—		—		—		—		8		8		—		8		8
Investment contracts	—		—		—		—		125		125		—		125		125
Total other investments	4		2		6		—		139		139		4		141		145

Total investments	$	945	$	2	$	947	$	3	$	420	$	423	$	948	$	422	$	1,370

As of December 31, 2011, the investments for our funded Transocean Plans were categorized as follows (in millions):

	December 31, 2011
	Significant observable inputs						Significant other observable inputs						Total
	U.S. Plans		Non-U.S. Plans		Transocean Plans		U.S. Plans		Non-U.S. Plans		Transocean Plans		U.S. Plans		Non-U.S. Plans		Transocean Plans
Mutual funds
U.S. equity funds	$	395	$	—	$	395	$	—	$	29	$	29	$	395	$	29	$	424
Non-U.S. equity funds	91		—		91		2		137		139		93		137		230
Bond funds	278		—		278		—		43		43		278		43		321
Total mutual funds	764		—		764		2		209		211		766		209		975

Other investments
Cash and money market funds	3		38		41		—		—		—		3		38		41
Property collective trusts	—		—		—		—		8		8		—		8		8
Investment contracts	—		—		—		—		96		96		—		96		96
Total other investments	3		38		41		—		104		104		3		142		145

Total investments	$	767	$	38	$	805	$	2	$	313	$	315	$	769	$	351	$	1,120

The U.S. Plans and the U.K. Plan invest primarily in passively managed funds that reference market indices. The funded Norway Plans are subject to contractual terms under selected insurance programs. Each plan’s investment managers have discretion to select the securities held within each asset category. Given this discretion, the managers may occasionally invest in our debt or equity securities, and may hold either long or short positions in such securities. As the plan investment managers are required to maintain well diversified portfolios, the actual investment in our securities would be immaterial relative to asset categories and the overall plan assets.

Net periodic benefit costs—Net periodic benefit costs, before tax, included the following components (in millions):

	Year ended December 31, 2012									Year ended December 31, 2011									Year ended December 31, 2010
	U.S. Plans			Non-U.S. Plans			Transocean Plans			U.S. Plans			Non-U.S. Plans			Transocean Plans			U.S. Plans			Non-U.S. Plans			Transocean Plans
Service cost	$	49		$	31		$	80		$	43		$	21		$	64		$	42		$	20		$	62
Interest cost	59			24			83			58			22			80			54			20			74
Expected return on plan assets	(62		)	(22		)	(84		)	(63		)	(23		)	(86		)	(58		)	(17		)	(75		)
Settlements and curtailments	3			19			22			2			1			3			5			3			8
Special termination benefits	1			—			1			—			—			—			3			—			3
Actuarial losses, net	41			4			45			23			4			27			13			4			17
Prior service cost (credit), net	(2		)	1			(1		)	(1		)	—			(1		)	(1		)	—			(1		)
Transition obligation, net	—			—			—			—			—			—			—			1			1
Net periodic benefit costs	$	89		$	57		$	146		$	62		$	25		$	87		$	58		$	31		$	89

For the OPEB Plans, the combined components of net periodic benefit costs, including service cost, interest cost, recognized net actuarial losses and prior service cost amortization were $3 million, $1 million and $2 million in the years ended December 31, 2012, 2011 and 2010, respectively.

The following table presents the amounts in accumulated other comprehensive income, before tax, that have not been recognized as components of net periodic benefit costs (in millions):

	December 31, 2012											December 31, 2011
	U.S. Plans			Non-U.S. Plans		OPEB Plans			Total			U.S. Plans			Non-U.S. Plans			OPEB Plans			Total
Actuarial loss, net	$	477		$	80	$	8		$	565		$	447		$	113		$	4		$	564
Prior service cost (credit), net	(8		)	—		(2		)	(10		)	(10		)	—			(2		)	(12		)
Transition obligation, net	—			—		—			—			—			(2		)	—			(2		)
Total	$	469		$	80	$	6		$	555		$	437		$	111		$	2		$	550

The following table presents the amounts in accumulated other comprehensive income expected to be recognized as components of net periodic benefit costs during the year ending December 31, 2013 (in millions):

	Year ending December 31, 2013
	U.S. Plans			Non-U.S. Plans		OPEB Plans			Total
Actuarial loss, net	$	48		$	4	$	1		$	53
Prior service cost (credit), net	(1		)	—		(1		)	(2		)
Transition obligation, net	—			—		—			—
Total amount expected to be recognized	$	47		$	4	$	—		$	51

Funding contributions—In the years ended December 31, 2012, 2011 and 2010, we contributed $159 million, $103 million and $118 million, respectively, to the Transocean Plans and the OPEB Plans using our cash flows from operations. For the year ending December 31, 2013, we expect to contribute $50 million to the Transocean Plans, and we expect to fund benefit payments of approximately $4 million for the OPEB Plans as costs are incurred.

Benefit payments—The following were the projected benefits payments (in millions):

	U.S. Plans		Non-U.S. Plans		OPEB Plans		Total
Years ending December 31,
2013	$	43	$	28	$	4	$	75
2014	47		11		4		62
2015	51		10		4		65
2016	55		11		4		70
2017	59		11		4		74
2018-2022	349		82		22		453

Defined contribution plans

We sponsor three defined contribution plans, including (1) one qualified defined contribution savings plan covering certain employees working in the U.S. (the “U.S. Savings Plan”), (2) one defined contribution savings plan covering certain employees working outside the U.S. and U.K. (the “Non-U.S. Savings Plan”), and (3) one defined contribution pension plan that covers certain employees working outside the U.S. (the “Non-U.S. Pension Plan”).

For the U.S. Savings Plan and the Non-U.S. Savings Plan, we make a matching contribution of up to 6.0 percent of each covered employee’s base salary, based on the employee’s contribution to the plan. For the Non-U.S. Pension Plan, we contribute between 4.5 percent and 6.5 percent of each covered employee’s base salary, based on the employee’s years of eligible service. In the years ended December 31, 2012, 2011 and 2010, the expense related to our defined contribution plans was $85 million, $82 million and $69 million, respectively.

- Definition

The entire disclosure for pension and other postretirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Number 132R

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-Name Implementation Guide (Q and A)

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+ Details

Commitments and Contingencies

12 Months Ended

Dec. 31, 2012

Commitments and Contingencies

Commitments and Contingencies

Note 17—Commitments and Contingencies

Lease obligations

We have operating lease commitments expiring at various dates, principally for real estate, office space and office equipment. In 2009, we accepted delivery of Petrobras 10000, an asset held under a capital lease through August 2029. In the years ended December 31, 2012, 2011 and 2010, rental expenses for all leases, including leases with terms of less than one year, was approximately $97 million, $169 million and $98 million, respectively. As of December 31, 2012, future minimum rental payments related to non-cancellable operating leases and the capital lease were as follows (in millions):

	Capital lease			Operating leases
Years ending December 31,
2013	$	66		$	42
2014	72			38
2015	72			24
2016	72			21
2017	73			11
Thereafter	846			95
Total future minimum rental payment	$	1,201		$	231
Less amount representing imputed interest	(544		)
Present value of future minimum rental payments under capital leases	657
Less current portion included in debt due within one year	(20		)
Long-term capital lease obligation	$	637

At December 31, 2012 and 2011, the aggregate carrying amount of our assets held under capital lease was as follows (in millions):

	December 31,
	2012			2011
Property and equipment, cost	$	745		$	742
Accumulated depreciation	(64		)	(44		)
Property and equipment, net	$	681		$	698

In the years ended December 31, 2012, 2011 and 2010, depreciation expense associated with our assets held under capital lease was $20 million, $20 million and $23 million, respectively.

Purchase obligations

At December 31, 2012, our purchase obligations, primarily related to our newbuilds, were as follows (in millions):

	Purchase obligations
Years ending December 31,
2013	$	1,896
2014	447
2015	749
2016	674
2017	—
Thereafter	—
Total	$	3,766

Macondo well incident

Overview—On April 22, 2010, the Ultra-Deepwater Floater Deepwater Horizon sank after a blowout of the Macondo well caused a fire and explosion on the rig. Eleven persons were declared dead and others were injured as a result of the incident. At the time of the explosion, Deepwater Horizon was located approximately 41 miles off the coast of Louisiana in Mississippi Canyon Block 252 and was contracted to BP America Production Co. (together with its affiliates, “BP”).

We are currently unable to estimate the full impact the Macondo well incident will have on us. We have recognized a liability for estimated loss contingencies that we believe are probable and for which a reasonable estimate can be made. This liability takes into account certain events related to the litigation and investigations arising out of the incident. There are loss contingencies related to the Macondo well incident that we believe are reasonably possible and for which we do not believe a reasonable estimate can be made. These contingencies could increase the liabilities we ultimately recognize. As of December 31, 2012 and 2011, the liability associated for estimated loss contingencies that we believe are probable and for which a reasonable estimate can be made was $1.9 billion and $1.2 billion, respectively, recorded in other current liabilities.

We have also recognized an asset associated with the portion of our estimated losses, primarily related to the personal injury and fatality claims of our crew and vendors, that we believe is recoverable from insurance. Although we have available policy limits that could result in additional amounts recoverable from insurance, recovery of such additional amounts is not probable and we are not currently able to estimate such amounts (see “—Insurance coverage”). Our estimates involve a significant amount of judgment. As a result of new information or future developments, we may adjust our estimated loss contingencies arising out of the Macondo well incident or our estimated recoveries from insurance, and the resulting losses could have a material adverse effect on our consolidated statement of financial position, results of operations and cash flows. In the year ended December 31, 2012, we received $15 million of cash proceeds from insurance recoveries for losses related to the personal injury and fatality claims of our crew and vendors. Additionally, BP received $84 million of cash proceeds from insurance recoveries under our insurance program for losses that were covered under our contractual indemnity of BP (see “—Contractual indemnity”). The payments made to BP resulted in corresponding reductions of our insurance recoverable asset and contingent liability. As of December 31, 2012 and 2011, the insurance recoverable asset related to estimated losses primarily for additional personal injury and fatality claims of our crew and vendors that we believe are probable of recovery from insurance was $141 million and $233 million, respectively, recorded in other assets.

Many of the Macondo well related claims are pending in the U.S. District Court, Eastern District of Louisiana (the “MDL Court”). The first phase of a three-phase trial was originally scheduled to commence in March 2012. In March 2012, BP and the Plaintiff’s Steering Committee (the “PSC”) announced that they had agreed to a partial settlement related primarily to private party environmental and economic loss claims as well as response effort related claims (the “BP/PSC Settlement”). The BP/PSC Settlement agreement provides that (a) to the extent permitted by law, BP will assign to the settlement class certain of BP’s claims, rights and recoveries against us for damages with protections such that the settlement class is barred from collecting any amounts from us unless it is finally determined that we cannot recover such amounts from BP, and (b) the settlement class releases all claims for compensatory damages against us but purports to retain claims for punitive damages against us.

On December 21, 2012, the MDL Court granted final approval of the economic and property damage class settlement between BP and the PSC. After giving consideration to the BP/PSC Settlement, the MDL Court ordered that the first phase of the trial, at which liability will be determined, be rescheduled for February 2013. The MDL Court subsequently issued an order with a projected trial date of June 2013 for the second phase of the trial, which will address conduct related to stopping the release of hydrocarbons between April 22, 2010 and approximately September 19, 2010 and seek to determine the amount of oil actually released during the period. Due to discovery requirements, the second phase of the trial is being rescheduled to September 2013. There can be no assurance as to the outcome of the trial, as to the timing of any phase of trial, that we will not enter into additional settlements as to some or all of the matters related to the Macondo well incident, including those to be determined at a trial, or the timing or terms of any such settlements.

In April 2011, several defendants in the Macondo well litigation before the Multi-District Litigation Panel (the “MDL”) filed cross-claims or third-party claims against us and certain of our subsidiaries, and other defendants. BP filed a claim seeking contribution under the Oil Pollution Act of 1990 (“OPA”) and maritime law, subrogation and claimed breach of contract, unseaworthiness, negligence and gross negligence. BP also sought a declaration that it is not liable in contribution, indemnification, or otherwise to us. Anadarko Petroleum Corporation (“Anadarko”), which owned a 25 percent non-operating interest in the Macondo well, asserted claims of negligence, gross negligence, and willful misconduct and is seeking indemnity under state and maritime law and contribution under maritime and state law as well as OPA. MOEX Offshore 2007 LLC (“MOEX”), which owns a 10 percent non-operating interest in the Macondo well, filed claims of negligence under state and maritime law, gross negligence under state law, gross negligence and willful misconduct under maritime law and is seeking indemnity under state and maritime law and contribution under maritime law and OPA. Cameron International Corporation (“Cameron”), the manufacturer and designer of the blowout preventer, asserted multiple claims for contractual indemnity and declarations regarding contractual obligations under various contracts and quotes and is also seeking non-contractual indemnity and contribution under maritime law and OPA. As part of the BP/PSC Settlement, one or more of these claims against us and certain of our subsidiaries may be assigned to the PSC settlement class. Halliburton Company (“Halliburton”), which provided cementing and mud-logging services to the operator, filed a claim against us seeking contribution and indemnity under maritime law, contractual indemnity and alleging negligence and gross negligence. Additionally, certain other third parties filed claims against us for indemnity and contribution.

In April 2011, we filed cross-claims and counter-claims against BP, Halliburton, Cameron, Anadarko, MOEX, certain of these parties’ affiliates, the U.S. and certain other third parties. We seek indemnity, contribution, including contribution under OPA, and subrogation under OPA, and we have asserted claims for breach of warranty of workmanlike performance, strict liability for manufacturing and design defect, breach of express contract, and damages for the difference between the fair market value of Deepwater Horizon and the amount received from insurance proceeds. Our agreement with the DOJ limits our ability to seek indemnification with respect to certain of these matters against the owners of the Macondo well. We are not pursuing arbitration on the key contractual issues with BP; instead, we are relying on the court to resolve the disputes. With regard to the U.S., we are not currently seeking recovery of monetary damages, but rather a declaration regarding relative fault and contribution via credit, setoff, or recoupment.

Notices of alleged non-compliance—The Department of the Interior’s Bureau of Safety and Environmental Enforcement issued four notices of alleged non-compliance with regulatory requirements to us on October 12, 2011. See Note 29—Subsequent Events.

Insurance coverage—At the time of the Macondo well incident, our excess liability insurance program offered aggregate insurance coverage of $950 million, excluding a $15 million deductible and a $50 million self-insured layer through our wholly owned captive insurance subsidiary. This excess liability insurance coverage consisted of a first and a second layer of $150 million each, a third and fourth layer of $200 million each and a fifth layer of $250 million. The first four excess layers have similar coverage and contractual terms, while the $250 million fifth layer is on a different policy form, which varies to some extent from the underlying coverage and contractual terms. Generally, we believe that the policy forms for all layers include coverage for personal injury and fatality claims of our crew and vendors, actual and compensatory damages, punitive damages and related legal defense costs and that the policy forms for the first four excess layers provide coverage for fines; however, we do not expect payments deemed to be criminal in nature to be covered by any of the layers.

In May 2010, we received notice from BP maintaining that it believes that it is entitled to additional insured status under our excess liability insurance program. Our insurers have also received notices from Anadarko and MOEX advising of their intent to preserve any rights they may have to our insurance policies as an additional insured under the drilling contract. In response, our wholly owned captive insurance subsidiary and our first four excess layer insurers filed declaratory judgment actions in the Houston Division of the U.S. District Court for the Southern District of Texas in May 2010 seeking a judgment declaring that they have limited additional insured obligations to BP, Anadarko and MOEX. We are parties to the declaratory judgment actions, which have been transferred to the MDL Court for discovery and other purposes. On November 15, 2011, the MDL Court ruled that BP’s coverage rights are limited to the scope of our indemnification of BP in the drilling contract. A final judgment was entered against BP, Anadarko and MOEX, and BP has filed an appeal. Oral argument took place in December 2012 and we are currently awaiting the appellate court ruling. We believe that additional insured coverage for BP, Anadarko or MOEX under the $250 million fifth layer of our insurance program is also limited to the scope of our indemnification of BP under the drilling contract. While we cannot predict the outcome of the appeal, we do not expect it to have a material adverse effect on our consolidated statement of financial position, results of operations or cash flows.

Additionally, our first layer of excess insurers, representing $150 million of insurance coverage, filed interpleader actions on June 17, 2011. The insurers contend that they face multiple, and potentially competing, claims to the relevant insurance proceeds. In these actions, the insurers effectively ask the court to manage disbursement of the funds to the alleged claimants, as appropriate, and discharge the insurers of any additional liability. The parties to the interpleader actions have executed a protocol agreement to facilitate the reimbursement and funding of settlements of personal injury and fatality claims of our crew and vendors using insurance funds and claims have been submitted to the court for review. Pending the court’s determination of the parties’ claims, and with the court’s approval, the insurers have made interim reimbursement payments to the parties.

Our second layer of excess insurers, representing $150 million of insurance coverage, filed an interpleader action on July 31, 2012. Like the interpleader actions filed by the first layer of excess insurers, the second layer of excess insurers contend that they face multiple, and potentially competing, claims to the relevant insurance proceeds. In this action, the insurers effectively ask the court to manage disbursement of the funds to the alleged claimants, as appropriate, and discharge the insurers of any additional liability.

See Note 29—Subsequent Events.

Litigation—As of December 31, 2012, 383 actions or claims were pending against us, along with other unaffiliated defendants, in state and federal courts. Additionally, government agencies have initiated investigations into the Macondo well incident. We have categorized below the nature of the legal actions or claims. We are evaluating all claims and intend to vigorously defend any claims and pursue any and all defenses available. In addition, we believe we are entitled to contractual defense and indemnity for all wrongful death and personal injury claims made by non-employees and third-party subcontractors’ employees as well as all liabilities for pollution or contamination, other than for pollution or contamination originating on or above the surface of the water. See “—Contractual indemnity.”

Wrongful death and personal injury—As of December 31, 2012, we have been named, along with other unaffiliated defendants, in nine complaints that were pending in state and federal courts in Louisiana and Texas involving multiple plaintiffs that allege wrongful death and other personal injuries arising out of the Macondo well incident. Per the order of the MDL, these claims have been centralized for discovery purposes in the MDL Court. The complaints generally allege negligence and seek awards of unspecified economic damages and punitive damages. BP, MI-SWACO, Weatherford International Ltd. and Cameron and certain of their affiliates, have, based on contractual arrangements, also made indemnity demands upon us with respect to personal injury and wrongful death claims asserted by our employees or representatives of our employees against these entities. See “—Contractual indemnity.”

Economic loss—As of December 31, 2012, we and certain of our subsidiaries were named, along with other unaffiliated defendants, in 153 pending individual complaints as well as 188 putative class-action complaints that were pending in the federal and state courts in Louisiana, Texas, Mississippi, Alabama, Georgia, Kentucky, South Carolina, Tennessee, Florida and possibly other courts. The complaints generally allege, among other things, potential economic losses as a result of environmental pollution arising out of the Macondo well incident and are based primarily on the OPA and state OPA analogues. The plaintiffs are generally seeking awards of unspecified economic, compensatory and punitive damages, as well as injunctive relief. These actions have been transferred to the MDL. See “—Contractual indemnity.”

Federal securities claims—A federal securities class action is currently pending in the U.S. District Court, Southern District of New York, naming us and former chief executive officers of Transocean Ltd. and one of our acquired companies as defendants. In the action, a former shareholder of the acquired company alleges that the joint proxy statement related to our shareholder meeting in connection with our merger with the acquired company violated Section 14(a) of the Exchange Act of 1934 (the “Exchange Act”), Rule 14a-9 promulgated thereunder and Section 20(a) of the Exchange Act. The plaintiff claims that the acquired company’s shareholders received inadequate consideration for their shares as a result of the alleged violations and seeks compensatory and rescissory damages and attorneys’ fees. In addition, we are obligated to pay the defense fees and costs for the individual defendants, which may be covered by our directors’ and officers’ liability insurance, subject to a deductible. On October 4, 2012, the court denied our motion to dismiss the action. On October 5, 2012, we asked the court to stay the action pending a decision by the Second Circuit Court of Appeals in an unrelated action involving other parties on the grounds that the Second Circuit’s decision could be relevant to the disposition of this case. On October 10, 2012, the court stayed discovery pending a decision on the motion to stay. See Note 29—Subsequent Events.

Other federal statutes—Several of the claimants have made assertions under the statutes, including the Clean Water Act (the “CWA”), the Endangered Species Act, the Migratory Bird Treaty Act, the Clean Air Act, the Comprehensive Environmental Response Compensation and Liability Act and the Emergency Planning and Community Right-to-Know Act.

Shareholder derivative claims—In June 2010, two shareholder derivative suits were filed by our shareholders naming us as a nominal defendant and certain of our current and former officers and directors as defendants in state district court in Texas. These cases allege breach of fiduciary duty, unjust enrichment, abuse of control, gross mismanagement and waste of corporate assets in connection with the Macondo well incident. The plaintiffs are generally seeking to recover, on behalf of us, damages to the corporation and disgorgement of all profits, benefits, and other compensation from the individual defendants. Any recovery of the damages or disgorgement by the plaintiffs in these actions would be paid to us. If the plaintiffs prevail, we could be required to pay plaintiffs’ attorneys’ fees. In addition, we are obligated to pay the defense fees and costs for the individual defendants, which may be covered by our directors’ and officers’ liability insurance, subject to a deductible. The two actions have been consolidated before a single judge. The defendants have filed a motion to dismiss the complaint on the ground that if the actions are to proceed they must be maintained in the courts of Switzerland and on the ground that the plaintiffs lack standing to assert the claims alleged. In December 2012, in response to defendants’ motion to dismiss for lack of standing, the plaintiffs dismissed their action without prejudice.

U.S. Department of Justice claims—On December 15, 2010, the U.S. Department of Justice (“DOJ”) filed a civil lawsuit against us and other unaffiliated defendants. The complaint alleged violations under OPA and the CWA, including claims for per barrel civil penalties of up to $1,100 per barrel or up to $4,300 per barrel if gross negligence or willful misconduct is established, and the DOJ reserved its rights to amend the complaint to add new claims and defendants. The U.S. government has estimated that up to 4.1 million barrels of oil were discharged and subject to penalties. The complaint asserted that all defendants named are jointly and severally liable for all removal costs and damages resulting from the Macondo well incident. On December 6, 2011, the DOJ filed a motion for partial summary judgment seeking a ruling that we were jointly and severely liable under OPA, and liable for civil penalties under the CWA, for all of the discharges from the Macondo well on the theory that discharges not only came from the well but also from the blowout preventer and riser, appurtenances of Deepwater Horizon.

On January 9, 2012, we filed our opposition to the motion and filed a cross-motion for partial summary judgment seeking a ruling that we are not liable for the subsurface discharge of hydrocarbons. On February 22, 2012, the MDL Court ruled that we are not liable as a responsible party for damages under OPA with respect to the below surface discharges from the Macondo well. The court also ruled that the below surface discharge was discharged from the well facility, and not from the Deepwater Horizon vessel, within the meaning of the CWA, and that we therefore are not liable for such discharges as an owner of the vessel under the CWA. However, the court ruled that the issue of whether we could be held liable for such discharge under the CWA as an “operator” of the well facility could not be resolved on summary judgment. The court did not determine whether we could be liable for removal costs under OPA, or the extent of such removal costs. On August 27, 2012, Anadarko filed a notice of appeal seeking to appeal to the Fifth Circuit Court of Appeals that portion of the MDL Court’s February 22, 2012 ruling concerning liability under the CWA. On September 18, 2012, BP and the U.S. also filed notices of appeal seeking to appeal to the Fifth Circuit Court of Appeals the MDL Court’s February 22, 2012 ruling without limiting the notice of appeal to the CWA aspects of the ruling. We filed a motion to dismiss the appeals.

In addition to the civil complaint, the DOJ served us with civil investigative demands on December 8, 2010. These demands were part of an investigation by the DOJ to determine if we made false claims, or false statements in support of claims, in violation of the False Claims Act, in connection with the operator’s acquisition of the leasehold interest in the Mississippi Canyon Block 252, Gulf of Mexico and drilling operations on Deepwater Horizon.

The DOJ is also conducting a criminal investigation into the Macondo well incident. On March 7, 2011, the DOJ announced the formation of a new task force to lead the criminal investigation. The task force is investigating possible violations by us and certain unaffiliated parties of the CWA, the Migratory Bird Treaty Act, the Refuse Act, the Endangered Species Act, and the Seaman’s Manslaughter Act, among other federal statutes, and possible criminal liabilities, including fines under those statutes and under the Alternative Fines Act. Under the Alternatives Fines Act, a corporate defendant convicted of a criminal offense may be subject to a fine in the amount of twice the gross pecuniary loss suffered by third parties as a result of the offense. If we are charged with or convicted of certain criminal offenses, we may be subject to suspension or debarment as a contractor or subcontractor on certain government contracts, including leases.

See Note 29—Subsequent Events.

State and other government claims—In June 2010, the Louisiana Department of Environmental Quality (the “LDEQ”) issued a consolidated compliance order and notice of potential penalty to us and certain of our subsidiaries asking us to eliminate and remediate discharges of oil and other pollutants into waters and property located in the State of Louisiana, and to submit a plan and report in response to the order. In October 2010, the LDEQ rescinded its enforcement actions against us and our subsidiaries but reserved its rights to seek civil penalties for future violations of the Louisiana Environmental Quality Act.

In September 2010, the State of Louisiana filed a declaratory judgment seeking to designate us as a responsible party under OPA and the Louisiana Oil Spill Prevention and Response Act for the discharges emanating from the Macondo well.

Additionally, suits have been filed by the State of Alabama and the cities of Greenville, Evergreen, Georgiana and McKenzie, Alabama in the U.S. District Court, Middle District of Alabama; the Mexican States of Veracruz, Quintana Roo and Tamaulipas in the U.S. District Court, Western District of Texas; and the City of Panama City Beach, Florida in the U.S. District Court, Northern District of Florida. Suits were also filed by the City of New Orleans, by and on behalf of multiple Parishes, and by or on behalf of the Town of Grand Isle, Grand Isle Independent Levee District, the Town of Jean Lafitte, the Lafitte Area Independent Levee District, the City of Gretna, the City of Westwego, and the City of Harahan in the MDL Court. Additional suits were filed by or on behalf of other Parishes in the respective Parish courts and were removed to federal court. A local government master complaint also was filed in which cities, municipalities, and other local government entities can and have joined. Generally, these governmental entities allege economic losses under OPA and other statutory environmental state claims and also assert various common law state claims. The claims have been centralized in the MDL. The city of Panama City Beach’s claim was voluntarily dismissed.

On August 26, 2011, the MDL Court ruled on the motion to dismiss certain economic loss claims. The court ruled that state law, both statutory and common law, is preempted by maritime law, notwithstanding OPA’s savings provisions. Accordingly, all claims brought under state law were dismissed. Secondly, general maritime law claims that do not allege physical damage to a proprietary interest were dismissed, unless the claim falls into the commercial fisherman exception. The court ruled that OPA claims for economic loss do not require physical damage to a proprietary interest. Third, the MDL Court ruled that presentment under OPA is a mandatory condition precedent to filing suit against a responsible party. Finally, the MDL Court ruled that claims for punitive damages may be available under general maritime law in claims against responsible parties and non-responsible parties. Certain Louisiana parishes have appealed portions of this ruling. The parties have completed appellate briefing.

The Mexican States’ OPA claims were dismissed for failure to demonstrate that recovery under OPA was authorized by treaty or executive agreement. However, the Court preserved some of the Mexican States’ negligence and gross negligence claims, but only to the extent there has been a physical injury to a proprietary interest. As such, the ruling as to the Mexican States is not yet final and not subject to appeal at this time.

By letter dated May 5, 2010, the Attorneys General of the five Gulf Coast states of Alabama, Florida, Louisiana, Mississippi and Texas informed us that they intend to seek recovery of pollution clean-up costs and related damages arising from the Macondo well incident. In addition, by letter dated June 21, 2010, the Attorneys General of the 11 Atlantic Coast states of Connecticut, Delaware, Georgia, Maine, Maryland, Massachusetts, New Hampshire, New York, North Carolina, Rhode Island and South Carolina informed us that their states have not sustained any damage from the Macondo well incident but they would like assurances that we will be responsible financially if damages are sustained. We responded to each letter from the Attorneys General and indicated that we intend to fulfill our obligations as a responsible party for any discharge of oil from Deepwater Horizon on or above the surface of the water, and we assume that the operator will similarly fulfill its obligations under OPA for discharges from the undersea well.

Wreck removal—By letter dated December 6, 2010, the U.S. Coast Guard requested us to formulate and submit a comprehensive oil removal plan to remove any diesel fuel contained in the sponsons and fuel tanks that can be recovered from Deepwater Horizon. We have conducted a survey of the rig wreckage and have confirmed that no diesel fuel remains on the rig. We have insurance coverage for wreck removal for up to 25 percent of Deepwater Horizon’s insured value, or $140 million, with any excess wreck removal liability generally covered to the extent of our remaining excess liability limits. The U.S. Coast Guard has not requested that we remove the rig wreckage from the sea floor.

Contractual indemnity—Under our drilling contract for Deepwater Horizon, the operator has agreed, among other things, to assume full responsibility for and defend, release and indemnify us from any loss, expense, claim, fine, penalty or liability for pollution or contamination, including control and removal thereof, arising out of or connected with operations under the contract other than for pollution or contamination originating on or above the surface of the water from hydrocarbons or other specified substances within the control and possession of the contractor, as to which we agreed to assume responsibility and protect, release and indemnify the operator. Although we do not believe it is applicable to the Macondo well incident, we also agreed to indemnify and defend the operator up to a limit of $15 million for claims for loss or damage to third parties arising from pollution caused by the rig while it is off the drilling location, while the rig is underway or during drive off or drift off of the rig from the drilling location. The operator has also agreed, among other things, (1) to defend, release and indemnify us against loss or damage to the reservoir, and loss of property rights to oil, gas and minerals below the surface of the earth and (2) to defend, release and indemnify us and bear the cost of bringing the well under control in the event of a blowout or other loss of control. We agreed to defend, release and indemnify the operator for personal injury and death of our employees, invitees and the employees of our subcontractors while the operator agreed to defend, release and indemnify us for personal injury and death of its employees, invitees and the employees of its other subcontractors, other than us. We have also agreed to defend, release and indemnify the operator for damages to the rig and equipment, including salvage or removal costs.

Although we believe we are entitled to contractual defense and indemnity, the operator has sought to avoid its indemnification obligations. The operator has generally reserved all of its rights. In doing so, the operator has cited a variety of possible legal theories based upon the contract and facts still to be developed. We believe this reservation of rights is without justification and that the operator is required to honor its indemnification obligations contained in our contract and described above.

In April 2011, the operator filed a claim seeking a declaration that it is not liable to us in contribution, indemnification, or otherwise. On November 1, 2011, we filed a motion for partial summary judgment, seeking enforcement of the indemnity obligations for pollution and civil fines and penalties contained in the drilling contract with the operator. On January 26, 2012, the court ruled that the drilling contract requires the operator to indemnify us for compensatory damages asserted by third parties against us related to pollution that did not originate on or above the surface of the water, even if the claim is the result of our strict liability, negligence, or gross negligence. The operator and others are appealing this ruling. The court also held that the operator does not owe us indemnity to the extent that we are held liable for civil penalties under the CWA or for punitive damages. The court deferred ruling on the operator’s argument that we breached the drilling contract or materially increased the operator’s risk or prejudiced its rights so as to vitiate the operator’s indemnity obligations. Our motion for partial summary judgment and the court’s ruling did not address the issue of contractual indemnity for criminal fines and penalties. The law generally considers contractual indemnity for criminal fines and penalties to be against public policy.

Other legal proceedings

Brazil Frade field incident—On or about November 7, 2011, oil was released from fissures in the ocean floor in the vicinity of a development well being drilled by Chevron off the coast of Rio de Janeiro in the Frade field with Sedco 706. The release was ultimately controlled, the well was plugged, and the released oil is being contained by Chevron.

On or about December 13, 2011, a federal prosecutor in the town of Campos in Rio de Janeiro State filed a civil public action against Chevron and us seeking BRL 20.0 billion, equivalent to approximately $10.0 billion, and seeking a preliminary and permanent injunction preventing Chevron and us from operating in Brazil. The prosecutor amended the requested injunction on December 15, 2011, to seek to prevent Chevron and us from conducting extraction or transportation activities in Brazil and to seek to require Chevron to stop the release and remediate its effects. On January 11, 2012, a judge of the federal court in Campos issued an order finding that the case should be transferred to the federal court in Rio de Janeiro. The prosecutor has appealed this jurisdictional decision and that appeal remains pending. On February 24, 2012, the court in Rio de Janeiro issued an order denying the federal prosecutor’s request for a preliminary injunction. The prosecutor further appealed this decision, and a three-judge panel heard the appeal on May 8, 2012. In July 2012, the appellate court granted the request for preliminary injunction. On September 22, 2012, the federal court in Rio de Janeiro served us with the preliminary injunction. The terms of this injunction required us to cease conducting extraction or transportation activities in Brazil within 30 days from the date of service. On September 28, 2012, the Brazilian Superior Court of Justice partially suspended this preliminary injunction. As a result of this suspension, the preliminary injunction only applied to our operations in the Campo de Frade field, and we could continue to operate in all other offshore oil and gas fields in Brazil. On November 27, 2012, the Court of Appeals in Rio de Janeiro ruled unanimously to suspend the entire preliminary injunction order, including the injunction in the Campo de Frade field that had been entered in July 2012. This ruling was published on December 5, 2012.

The prosecutor has announced that settlement discussions are underway for resolution of the civil proceedings. There can be no assurance that any settlement will be achieved or the timing or terms of such settlement. If these settlement efforts are not successful, the lawsuit will continue in the trial court, and there remains a risk that the preliminary injunction could be reinstated, or that at the conclusion of the case Brazilian authorities could permanently enjoin us from further operations in Brazil. If either or both of these events occur, it could have a material adverse effect on our consolidated statement of financial position, results of operations or cash flows.

On December 21, 2011, a federal police marshal investigating the release filed a report with the federal court in Rio de Janeiro State recommending the indictment of Chevron, us, and 17 individuals, five of whom are our employees. The report recommended indictment on four counts, three alleging environmental offenses and one alleging false statements by Chevron in connection with its cleanup efforts. On March 21, 2012, the Campos prosecutor recommended indictments against the two companies and the 17 individuals. The prosecutor requested that the defendants be enjoined from disposing of property and that bail be set at BRL 10 million for the companies and BRL 1 million for the individuals. Subsequently, the federal court in Campos ruled that it does not have jurisdiction over the matter, and the file was transferred to the court in Rio de Janeiro. On or about June 15, 2012, the Rio de Janeiro court amended the travel order to state that passports could be returned to the individuals and that the individuals could travel with prior notice to the court. The indictments must be approved by a court of competent jurisdiction to become effective, and the criminal judge can accept, reject or modify the charges. The court has not yet approved the indictments.

The drilling services and charter contracts between Chevron and us provide, among other things, for Chevron to indemnify and defend us for claims based on pollution or contamination originating from below the surface of the water, including claims for control or removal or property loss or damage, including but not limited to third-party claims and liabilities, with an excludable amount of $250,000 per occurrence if the claim arises from our negligence. We have submitted a claim for indemnity and defense to Chevron under these contracts. Chevron responded that our request was premature, and requested that we confirm our intent to indemnify and defend Chevron regarding alleged violations of safety regulations aboard Sedco 706 that have resulted in the issuance of notices of infractions and any other claims or liabilities that may fall within our legal obligations. By letter dated September 6, 2012, Chevron agreed to indemnify us for all claims and liabilities resulting in judgments, awards or other monetary assessments of a strictly compensatory nature for alleged damages arising from pollution or contamination that originated below the surface of the water in connection with the incident. Chevron has also agreed to assume our defense in the criminal and civil lawsuits. We have been engaged in subsequent discussions with Chevron regarding the parameters of Chevron’s agreement. We have yet to receive payment from Chevron.

On March 15, 2012, Chevron publicly announced that it had identified a new sheen in Frade field whose source was determined to be seepage from an 800-meter fissure 3 kilometers away from the location of the November incident. Chevron and the Brazilian National Agency of Petroleum have publicly stated that, while further studies are being conducted, the new seepage, which was estimated by Chevron, at the time, to be five liters, is now believed to be unrelated to the November incident.

On March 27, 2012, the union of oil industry workers in Brazil, Federacao Unica dos Petroleiros (“FUP”), filed a civil lawsuit in federal court in Rio de Janeiro against Chevron and us alleging a number of claims, including negligence on our part, and seeking a permanent injunction enjoining our operations in Brazil. The lawsuit sought unspecified damages. On or about April 16, 2012, the court issued an order transferring this case to the same court in Rio de Janeiro in which the initial civil public action is pending. On or about May 1, 2012, the Rio de Janeiro court dismissed this lawsuit, without prejudice, as duplicative of the other civil lawsuits. The FUP has appealed this dismissal. On October 26, 2012, the trial court issued an opinion suspending the lawsuit until a final decision is rendered on the merits on the first civil public action filed by the federal prosecutor; this opinion had the effect of staying the FUP’s appeal.

On or about April 3, 2012, the same federal prosecutor who filed the original civil public action and the criminal indictments filed a new civil public action against Chevron and us in federal court in Campos. This lawsuit alleges the new seepage discovered in March 2012 is related to the November 2011 incident and release. The lawsuit seeks an additional BRL 20.0 billion in damages, equivalent to approximately $10.0 billion. We have not been served in this matter.

On or about August 8, 2012, 43 private civil lawsuits were filed against Chevron and us in the Civil Court of Itapemirim. Each of these lawsuits has several claimants, with a total of 217 claimants in the 43 lawsuits. These lawsuits contain substantially identical allegations, claiming that the alleged pollution from the incident prevented the claimants from fishing. Each claimant seeks approximately BRL 72,000, equivalent to $35,000 in moral damages. These lawsuits were all served on us in November 2012. We have submitted these claims to Chevron for indemnity and defense but have not received confirmation of Chevron’s intent to indemnify and defend these actions. We also understand that an additional 49 lawsuits have been filed in the state of Espirito Santo, with similar allegations, seeking similar damages; these additional 49 lawsuits have not yet been served on us. We intend to submit these claims to Chevron for indemnity and defense as well.

We intend to defend ourselves vigorously against any claims that are brought based on the incident. While we cannot predict or provide assurance as to the final outcome of these proceedings, we do not expect it to have a material adverse effect on our consolidated statement of financial position, results of operations or cash flows.

Asbestos litigation—In 2004, several of our subsidiaries were named, along with numerous other unaffiliated defendants, in 21 complaints filed on behalf of 769 plaintiffs in the Circuit Courts of the State of Mississippi and which claimed injuries arising out of exposure to asbestos allegedly contained in drilling mud during these plaintiffs’ employment in drilling activities between 1965 and 1986. Each individual plaintiff was subsequently required to file a separate lawsuit, and the original 21 multi-plaintiff complaints were then dismissed by the Circuit Courts. We have or may have an indirect interest in a total of 26 cases. The complaints generally allege that the defendants used or manufactured asbestos-containing drilling mud additives for use in connection with drilling operations and have included allegations of negligence, products liability, strict liability and claims allowed under the Jones Act and general maritime law. The plaintiffs generally seek awards of unspecified compensatory and punitive damages. In each of these cases, the complaints have named other unaffiliated defendant companies, including companies that allegedly manufactured the drilling-related products that contained asbestos. All of these cases are being governed for discovery and trial setting by a single Case Management Order entered by a Special Master appointed by the court to reside over all the cases, and of the 14 cases in which we are a named defendant, only one has been scheduled for trial and pre-trial discovery, which was scheduled to take place in 2013. In that case, we recently were able to present a variety of pre-trial defense motions challenging the plaintiff’s evidence and resulting in a negotiated settlement for a nominal sum in the fourth quarter of 2012. In 2011, the Special Master issued a ruling that a Jones Act employer defendant, such as us, cannot be sued for punitive damages, and this ruling has now been obtained in three of our 14 cases. To date, seven of the 769 cases have gone to trial against defendants who allegedly manufactured or distributed drilling mud additives. None of these cases have involved an individual Jones Act employer, and we have not been a defendant in any of these cases. Two of the cases resulted in defense verdicts, and one case ended with a hung jury. Four cases resulted in verdicts for the plaintiff. Because the jury awarded punitive damages, two of these cases resulted in a substantial verdict in favor of the plaintiff; however, both of these verdicts have since been vacated by the trial court. The first plaintiff verdict was vacated on the basis that the plaintiff failed to meet its burden of proof. While the court’s decision is consistent with our general evaluation of the strength of these cases, it is currently being reviewed on appeal. The second plaintiff verdict was vacated because the presiding judge was removed from hearing any asbestos cases due to a conflict of interest, but when this case ultimately went to trial earlier this year, it resulted in a defense verdict. The two remaining plaintiff verdicts are under appeal by the defendants. We intend to defend these lawsuits vigorously, although there can be no assurance as to the ultimate outcome. We historically have maintained broad liability insurance, although we are not certain whether insurance will cover the liabilities, if any, arising out of these claims. Based on our evaluation of the exposure to date, we do not expect the liability, if any, resulting from these claims to have a material adverse effect on our consolidated statement of financial position, results of operations or cash flows.

One of our subsidiaries was involved in lawsuits arising out of the subsidiary’s involvement in the design, construction and refurbishment of major industrial complexes. The operating assets of the subsidiary were sold and its operations discontinued in 1989, and the subsidiary has no remaining assets other than the insurance policies involved in its litigation, with its insurers and, either directly or indirectly through a qualified settlement fund. The subsidiary has been named as a defendant, along with numerous other companies, in lawsuits alleging bodily injury or personal injury as a result of exposure to asbestos. As of December 31, 2012, the subsidiary was a defendant in approximately 906 lawsuits, some of which include multiple plaintiffs, and we estimate that there are approximately 2,022 plaintiffs in these lawsuits. For many of these lawsuits, we have not been provided with sufficient information from the plaintiffs to determine whether all or some of the plaintiffs have claims against the subsidiary, the basis of any such claims, or the nature of their alleged injuries. The first of the asbestos-related lawsuits was filed against the subsidiary in 1990. Through December 31, 2012, the costs incurred to resolve claims, including both defense fees and expenses and settlement costs, have not been material, all known deductibles have been satisfied or are inapplicable, and the subsidiary’s defense fees and expenses and settlement costs have been met by insurance made available to the subsidiary. The subsidiary continues to be named as a defendant in additional lawsuits, and we cannot predict the number of additional cases in which it may be named a defendant nor can we predict the potential costs to resolve such additional cases or to resolve the pending cases. However, the subsidiary has in excess of $1.0 billion in insurance limits potentially available to the subsidiary. Although not all of the policies may be fully available due to the insolvency of certain insurers, we believe that the subsidiary will have sufficient funding directly or indirectly from settlements and claims payments from insurers, assigned rights from insurers and coverage-in-place settlement agreements with insurers to respond to these claims. While we cannot predict or provide assurance as to the final outcome of these matters, we do not believe that the current value of the claims where we have been identified will have a material impact on our consolidated statement of financial position, results of operations or cash flows.

Rio de Janeiro tax assessment—In the third quarter of 2006, we received tax assessments of BRL 379 million, equivalent to approximately $185 million, including interest and penalties, from the state tax authorities of Rio de Janeiro in Brazil against one of our Brazilian subsidiaries for taxes on equipment imported into the state in connection with our operations. The assessments resulted from a preliminary finding by these authorities that our subsidiary’s record keeping practices were deficient. We currently believe that the substantial majority of these assessments are without merit. We filed an initial response with the Rio de Janeiro tax authorities on September 9, 2006 refuting these additional tax assessments. In September 2007, we received confirmation from the state tax authorities that they believe the additional tax assessments are valid, and as a result, we filed an appeal on September 27, 2007 to the state Taxpayer’s Council contesting these assessments. While we cannot predict or provide assurance as to the final outcome of these proceedings, we do not expect it to have a material adverse effect on our consolidated statement of financial position, results of operations or cash flows.

Brazilian import license assessment—In the fourth quarter of 2010, one of our Brazilian subsidiaries received an assessment from the Brazilian federal tax authorities in Rio de Janeiro of BRL 487 million, equivalent to approximately $238 million, including interest and penalties, based upon the alleged failure to timely apply for import licenses for certain equipment and for allegedly providing improper information on import license applications. We believe that a substantial majority of the assessment is without merit and are vigorously pursuing legal remedies. The case was decided partially in favor of our Brazilian subsidiary in the lower administrative court level. The decision cancelled the majority of the assessment, reducing the total assessment to BRL 30 million, equivalent to approximately $15 million. On July 14, 2011, our Brazilian subsidiary filed an appeal to eliminate the assessment. We have not received a ruling on the appeal. While we cannot predict or provide assurance as to the final outcome of these proceedings, we do not expect it to have a material adverse effect on our consolidated statement of financial position, results of operations or cash flows.

Other matters—We are involved in various tax matters and various regulatory matters. We are also involved in lawsuits relating to damage claims arising out of hurricanes Katrina and Rita, all of which are insured and which are not material to us. As of December 31, 2012, we were involved in a number of other lawsuits, including a dispute for municipal tax payments in Brazil and a dispute involving customs procedures in India, neither of which is material to us, and all of which have arisen in the ordinary course of our business. We do not expect the liability, if any, resulting from these other matters to have a material adverse effect on our consolidated statement of financial position, results of operations or cash flows. We cannot predict with certainty the outcome or effect of any of the litigation matters specifically described above or of any such other pending or threatened litigation. There can be no assurance that our beliefs or expectations as to the outcome or effect of any lawsuit or other litigation matter will prove correct and the eventual outcome of these matters could materially differ from management’s current estimates.

Other environmental matters

Hazardous waste disposal sites—We have certain potential liabilities under the Comprehensive Environmental Response, Compensation and Liability Act (“CERCLA”) and similar state acts regulating cleanup of various hazardous waste disposal sites, including those described below. CERCLA is intended to expedite the remediation of hazardous substances without regard to fault. Potentially responsible parties (“PRPs”) for each site include present and former owners and operators of, transporters to and generators of the substances at the site. Liability is strict and can be joint and several.

We have been named as a PRP in connection with a site located in Santa Fe Springs, California, known as the Waste Disposal, Inc. site. We and other PRPs have agreed with the U.S. Environmental Protection Agency (“EPA”) and the DOJ to settle our potential liabilities for this site by agreeing to perform the remaining remediation required by the EPA. The form of the agreement is a consent decree, which has been entered by the court. The parties to the settlement have entered into a participation agreement, which makes us liable for approximately eight percent of the remediation and related costs. The remediation is complete, and we believe our share of the future operation and maintenance costs of the site is not material. There are additional potential liabilities related to the site, but these cannot be quantified, and we have no reason at this time to believe that they will be material.

One of our subsidiaries has been ordered by the California Regional Water Quality Control Board (“CRWQCB”) to develop a testing plan for a site known as Campus 1000 Fremont in Alhambra, California. This site was formerly owned and operated by certain of our subsidiaries. It is presently owned by an unrelated party, which has received an order to test the property. We have also been advised that one or more of our subsidiaries is likely to be named by the EPA as a PRP for the San Gabriel Valley, Area 3, Superfund site, which includes this property. Testing has been completed at the property but no contaminants of concern were detected. In discussions with CRWQCB staff, we were advised of their intent to issue us a “no further action” letter but it has not yet been received. Based on the test results, we would contest any potential liability. We have no knowledge at this time of the potential cost of any remediation, who else will be named as PRPs, and whether in fact any of our subsidiaries is a responsible party. The subsidiaries in question do not own any operating assets and have limited ability to respond to any liabilities.

Resolutions of other claims by the EPA, the involved state agency or PRPs are at various stages of investigation. These investigations involve determinations of:

· the actual responsibility attributed to us and the other PRPs at the site;

· appropriate investigatory or remedial actions; and

· allocation of the costs of such activities among the PRPs and other site users.

Our ultimate financial responsibility in connection with those sites may depend on many factors, including:

· the volume and nature of material, if any, contributed to the site for which we are responsible;

· the number of other PRPs and their financial viability; and

· the remediation methods and technology to be used.

It is difficult to quantify with certainty the potential cost of these environmental matters, particularly in respect of remediation obligations. Nevertheless, based upon the information currently available, we believe that our ultimate liability arising from all environmental matters, including the liability for all other related pending legal proceedings, asserted legal claims and known potential legal claims which are likely to be asserted, is adequately accrued and should not have a material effect on our statement of financial position or results of operations. Estimated costs of future expenditures for environmental remediation obligations are not discounted to their present value.

Retained risk

Our hull and machinery and excess liability insurance program consists of commercial market and captive insurance policies. We periodically evaluate our insurance limits and self-insured retentions. As of December 31, 2012, the insured value of our drilling rig fleet was approximately $29.3 billion, excluding our rigs under construction.

Hull and machinery coverage—Under the hull and machinery program, we generally maintain a $125 million per occurrence deductible, limited to a maximum of $200 million per policy period. Subject to the same shared deductible, we also have coverage for costs incurred to mitigate damage to a rig up to an amount equal to 25 percent of a rig’s insured value. Also subject to the same shared deductible, we have additional coverage for wreck removal for up to 25 percent of a rig’s insured value, with any excess generally covered to the extent of our remaining excess liability coverage described below.

Excess liability coverage—We carry $775 million of commercial market excess liability coverage, exclusive of the deductibles and self-insured retention, noted below, which generally covers offshore risks such as personal injury, third-party property claims, and third-party non-crew claims, including wreck removal and pollution. Our excess liability coverage has (1) separate $10 million per occurrence deductibles on collision liability claims and (2) separate $5 million per occurrence deductibles on crew personal injury claims and on other third-party non-crew claims. Through our wholly owned captive insurance company, we have retained the risk of the primary $50 million excess liability coverage. In addition, we generally retain the risk for any liability losses in excess of $825 million.

Other insurance coverage—We also carry $100 million of additional insurance that generally covers expenses that would otherwise be assumed by the well owner, such as costs to control the well, redrill expenses and pollution from the well. This additional insurance provides coverage for such expenses in circumstances in which we have legal or contractual liability arising from our gross negligence or willful misconduct.

We have elected to self-insure operators extra expense coverage for ADTI. This coverage provides protection against expenses related to well control, pollution and redrill liability associated with blowouts. ADTI’s customers assume, and indemnify ADTI for, liability associated with blowouts in excess of a contractually agreed amount, generally $50 million.

We do not generally carry commercial market insurance coverage for loss of revenue unless it is contractually required. We do not generally carry commercial market insurance coverage for our fleet for physical damage losses, including liability for wreck removal expenses, which are caused by named windstorms in the U.S. Gulf of Mexico.

Letters of credit and surety bonds

We had outstanding letters of credit totaling $522 million and $650 million at December 31, 2012 and 2011, respectively, issued under various committed and uncommitted credit lines provided by several banks to guarantee various contract bidding, performance activities and customs obligations. Included in the $522 million outstanding letters of credit at December 31, 2012 were $113 million of letters of credit that we have agreed to retain in support of the operations for Shelf Drilling for up to three years following the closing of the sale transactions (see Note 9—Discontinued Operations).

As is customary in the contract drilling business, we also have various surety bonds in place that secure customs obligations relating to the importation of our rigs and certain performance and other obligations. We had outstanding surety bonds totaling $11 million and $12 million at December 31, 2012 and 2011, respectively.

- Definition

The entire disclosure for commitments and contingencies.

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+ Details

Redeemable Noncontrolling Interest

12 Months Ended

Dec. 31, 2012

Redeemable Noncontrolling Interest

Redeemable Noncontrolling Interest

Note 18—Redeemable Noncontrolling Interest

On February 29, 2012, Quantum exercised its rights under a put option agreement to exchange its interest in TPDI for our shares or cash, at its election. Based on the redemption value of Quantum’s interest as of that date, we adjusted the carrying amount of the noncontrolling interest and reclassified Quantum’s interest to other current liabilities with a corresponding adjustment in the amount of $106 million to retained earnings within shareholders’ equity. We estimated the fair value of Quantum’s interest using significant other observable inputs, representative of a Level 2 fair value measurement, including indications of market values of the drilling units owned by TPDI.

On March 29, 2012, Quantum elected to exchange its interest in TPDI for our shares, net of Quantum’s share of TPDI’s indebtedness, as defined in the put option agreement. Quantum had the right, prior to closing of this exchange, to change its election to cash, net of Quantum’s share of TPDI’s indebtedness.

The carrying amount of Quantum’s interest was measured at its estimated fair value through settlement of the exchange transaction on May 31, 2012, resulting in an adjustment of $25 million to increase the liability with corresponding adjustments to other expense on our consolidated statement of operations. On May 31, 2012, we issued 8.7 million shares to Quantum in a non-cash exchange for its interest in TPDI to satisfy our obligation, resulting in an adjustment of $134 million and $233 million to shares and additional paid-in capital, respectively. The adjustment included the extinguishment of $148 million of TPDI Notes payable to Quantum and accrued and unpaid interest of $14 million. As a result of this transaction, TPDI became our wholly owned subsidiary. In August 2012, we paid $72 million as the final cash settlement, representing 50 percent of TPDI’s working capital at May 29, 2012. See Note 27—Related Party Transactions.

Until February 29, 2012, Quantum had the unilateral right, pursuant to a put option agreement, to exchange its 50 percent interest in TPDI for our shares or cash, at its election, at an amount based on an appraisal of the fair value of the drillships that are owned by TPDI, subject to certain adjustments. Accordingly, we presented Quantum’s interest as redeemable noncontrolling interest on our consolidated balance sheets until Quantum exercised its rights under the put option agreement. Changes in redeemable noncontrolling interest were as follows (in millions):

	Years ended December 31,
	2012			2011			2010
Redeemable noncontrolling interest
Balance, beginning of period	$	116		$	41		$	—
Reclassification from noncontrolling interest	—			—			26
Net income attributable to noncontrolling interest	13			78			29
Other comprehensive loss attributable to noncontrolling interest	—			(3		)	(14		)
Fair value adjustment to redeemable noncontrolling interest	106			—			—
Reclassification to accumulated other comprehensive loss	17			—			—
Reclassification to other current liabilities	(252		)	—			—
Balance, end of period	$	—		$	116		$	41

Shareholders' Equity

12 Months Ended

Dec. 31, 2012

Shareholders' Equity

Shareholders' Equity

Note 19—Shareholders’ Equity

Distribution of qualifying additional paid-in capital—In May 2011, at our annual general meeting, our shareholders approved the distribution of additional paid-in capital in the form of a U.S. dollar denominated dividend of $3.16 per outstanding share, payable in four equal installments of $0.79 per outstanding share, subject to certain limitations. On June 15, 2011, September 21, 2011 and December 21, 2011, we paid the first three installments, in the aggregate amount of $763 million, to shareholders of record as of May 20, 2011, August 26, 2011, and November 25, 2011, respectively. On March 21, 2012, we paid the final installment in the aggregate amount of $278 million to shareholders of record as of February 24, 2012.

Share issuance— On May 31, 2012, we issued 8.7 million shares to Quantum in a non-cash exchange for its interest in TPDI. See Note 18—Redeemable Noncontrolling Interest.

In December 2011, we completed a public offering of 29.9 million shares at a price per share of $40.50, equivalent to CHF 37.19 using an exchange rate of USD 1.00 to CHF 0.9183. We received proceeds of $1.2 billion, net of underwriting discounts and commissions, issuance costs and the Swiss Federal Issuance Stamp Tax from the offering.

Shares held in treasury—In May 2009, at our annual general meeting, our shareholders approved and authorized our board of directors, at its discretion, to repurchase an amount of our shares for cancellation with an aggregate purchase price of up to CHF 3.5 billion, which is equivalent to approximately $3.8 billion, using an exchange rate of USD 1.00 to CHF 0.92 as of the close of trading on December 31, 2012. On February 12, 2010, our board of directors authorized our management to implement the share repurchase program.

During the years ended December 31, 2012 and 2011, we did not purchase any of our shares under our share repurchase program. During the year ended December 31, 2010, following the authorization by our board of directors, we repurchased 2.9 million of our shares under our share repurchase program for an aggregate purchase price of CHF 257 million, equivalent to $240 million. At December 31, 2012 and 2011, we held 2.9 million shares in treasury, recorded at cost.

Shares held by subsidiary—In December 2008, we issued 16.0 million of our shares to one of our subsidiaries for future use to satisfy our obligations to deliver shares in connection with awards granted under our incentive plans or other rights to acquire our shares. At December 31, 2012 and 2011, our subsidiary held approximately 11.5 million shares and 12.5 million shares, respectively.

Accumulated other comprehensive loss—The changes in accumulated other comprehensive loss for the years ended December 31, 2012 and 2011 were as follows (in millions):

	Year ended December 31, 2012												Year ended December 31, 2011
	Unrecognized components of net periodic benefit costs			Unrecognized gains (losses) on derivative instruments			Unrecognized gains (losses) on marketable securities			Total			Unrecognized components of net periodic benefit costs			Unrecognized gains (losses) on derivative instruments		Unrecognized gains (losses) on marketable securities			Total
Balance, beginning of period	$	(501	)	$	7		$	(2	)	$	(496	)	$	(335	)	$	5	$	(2	)	$	(332	)
Reclassification from redeemable noncontrolling interest	—			(17		)	—			(17		)	—			—		—			—
Other comprehensive income (loss) attributable to controlling interest	(10		)	—			2			(8		)	(166		)	2		—			(164		)
Balance, end of period	$	(511	)	$	(10	)	$	—		$	(521	)	$	(501	)	$	7	$	(2	)	$	(496	)

- Definition

The entire disclosure for shareholders' equity, comprised of portions attributable to the parent entity and noncontrolling interest, if any, including other comprehensive income (as applicable). Including, but not limited to: (1) balances of common stock, preferred stock, additional paid-in capital, other capital and retained earnings; (2) accumulated balance for each classification of other comprehensive income and total amount of comprehensive income; (3) amount and nature of changes in separate accounts, including the number of shares authorized and outstanding, number of shares issued upon exercise and conversion, and for other comprehensive income, the adjustments for reclassifications to net income; (4) rights and privileges of each class of stock authorized; (5) basis of treasury stock, if other than cost, and amounts paid and accounting treatment for treasury stock purchased significantly in excess of market; (6) dividends paid or payable per share and in the aggregate for each class of stock for each period presented; (7) dividend restrictions and accumulated preferred dividends in arrears (in aggregate and per share amount); (8) retained earnings appropriations or restrictions, such as dividend restrictions; (9) impact of change in accounting principle, initial adoption of new accounting principle and correction of an error in previously issued financial statements; (10) shares held in trust for Employee Stock Ownership Plan (ESOP); (11) deferred compensation related to issuance of capital stock; (12) note received for issuance of stock; (13) unamortized discount on shares; (14) description, terms, and number of warrants or rights outstanding; (15) shares under subscription and subscription receivables, effective date of new retained earnings after quasi-reorganization and deficit eliminated by quasi-reorganization and, for a period of at least ten years after the effective date, the point in time from which the new retained dates; and (16) retroactive effective of subsequent change in capital structure.

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-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 3

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-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 08

-Paragraph d

-Article 4

+ Details

Share-Based Compensation Plans

12 Months Ended

Dec. 31, 2012

Share-Based Compensation Plans

Share-Based Compensation Plans

Note 20—Share-Based Compensation Plans

Overview—We have (i) a long-term incentive plan (the “Long-Term Incentive Plan”) for executives, key employees and outside directors under which awards can be granted in the form of deferred units, restricted shares, stock options, stock appreciation rights and cash performance awards and (ii) other incentive plans under which awards are currently outstanding. Awards that may be granted under the Long-Term Incentive Plan include traditional time-vesting awards (“time-based awards”) and awards that are earned based on the achievement of certain performance criteria (“performance-based awards”) or market factors (“market-based awards”). Our executive compensation committee of our board of directors determines the terms and conditions of the awards granted under the Long-Term Incentive Plan. As of December 31, 2012, we had 36.0 million shares authorized and 10.9 million shares available to be granted under the Long-Term Incentive Plan.

Time-based awards typically vest either in three equal annual installments beginning on the first anniversary date of the grant or in an aggregate installment at the end of the stated vesting period. Performance-based and market-based awards are typically awarded subject to either a two-year or a three-year measurement period during which the number of options, shares or deferred units remains uncertain. At the end of the measurement period, the awarded number of options, shares or deferred units is determined (the “determination date”) subject to the stated vesting period. The two-year awards generally vest in three equal installments beginning on the determination date and on January 1 of each of the two subsequent years. The three-year awards generally vest in one aggregate installment following the determination date. Once vested, stock options and stock appreciation rights generally have a 10-year term during which they are exercisable.

As of December 31, 2012, total unrecognized compensation costs related to all unvested share-based awards were $95 million, which are expected to be recognized over a weighted-average period of 1.8 years. In the years ended December 31, 2012, 2011 and 2010, we recognized additional share-based compensation expense of $4 million, $3 million and $12 million, respectively, in connection with modifications of share-based awards.

Option valuation assumptions—We estimated the fair value of each option award under the Long-Term Incentive Plan on the grant date using the Black-Scholes-Merton option-pricing model with the following weighted-average assumptions:

	Years ended December 31,
	2012			2011			2010
Dividend yield	—			4		%	4		%
Expected price volatility	43		%	40		%	39		%
Risk-free interest rate	0.87		%	1.97		%	2.30		%
Expected life of options	5.0 years			4.9 years			4.7 years
Weighted-average fair value of options granted	$	18.87		$	19.75		$	30.03

Time-Based Awards

Deferred units—A deferred unit is a unit that is equal to one share but has no voting rights until the underlying shares are issued. The following table summarizes unvested activity for time-based vesting deferred units (“time-based units”) granted under our incentive plans during the year ended December 31, 2012:

	Number of units		Weighted-average grant-date fair value per share
Unvested at January 1, 2012	1,939,840		$	74.78
Granted	2,183,853		50.07
Vested	(1,064,359	)	71.57
Forfeited	(189,283	)	60.73
Unvested at December 31, 2012	2,870,051		$	58.09

The total grant-date fair value of the time-based units that vested during the year ended December 31, 2012 was $74 million.

There were 1,090,747 and 1,055,367 time-based units granted during the years ended December 31, 2011 and 2010, respectively. The weighted-average grant-date fair value of time-based units granted was $77.55 and $76.83 per share for the years ended December 31, 2011 and 2010, respectively. There were 832,252 and 559,339 time-based units that vested during the years ended December 31, 2011 and 2010, respectively. The total grant-date fair value of the time-based units that vested was $66 million and $45 million for the years ended December 31, 2011 and 2010, respectively. There were 163,439 and 106,691 time-based units that were forfeited during the years ended December 31, 2011 and 2010, respectively. The total grant date fair value of the time-based units that were forfeited was $13 million and $8 million for the years ended December 31, 2011 and 2010, respectively.

Restricted shares—We did not grant time-based vesting restricted shares (“time-based shares”) during the years ended December 31, 2012, 2011 and 2010. There were no time-based shares that vested during the year ended December 31, 2012. There were 3,939 and 92,573 time-based shares that vested during the years ended December 31, 2011 and 2010, respectively. The total grant-date fair value of time-based shares that vested was $1 million and $10 million for the years ended December 31, 2011 and 2010, respectively.

Stock options—The following table summarizes activity for vested and unvested time-based vesting stock options (“time-based options”) outstanding under our incentive plans during the year ended December 31, 2012:

	Number of shares under option		Weighted-average exercise price per share		Weighted-average remaining contractual term (years)	Aggregate intrinsic value (in millions)
Outstanding at January 1, 2012	1,579,284		$	70.16	5.43	$	—
Granted	395,673		50.79
Exercised	(264,707	)	36.50
Forfeited	(55,533	)	59.65
Expired	(38,662	)	53.51
Outstanding at December 31, 2012	1,616,055		$	71.69	6.30	$	—

Vested and exercisable at December 31, 2012	1,088,127		$	77.24	5.15	$	—

The weighted-average grant-date fair value of time-based options granted during the year ended December 31, 2012 was $18.87 per time-based option. The total grant-date fair value of time-based options that vested during the year ended December 31, 2012 was $5 million. The total pre-tax intrinsic value of time-based options exercised during the year ended December 31, 2012 was $3 million. At January 1 and December 31, 2012, we have presented the aggregate intrinsic value as zero since the weighted-average exercise price per share exceeded the market price of our shares on these dates. There were 348,666 unvested time-based options outstanding as of December 31, 2012.

There were time-based options to purchase 194,342 and 253,288 shares granted during the years ended December 31, 2011 and 2010, respectively. The weighted-average grant-date fair value of time-based options granted was $19.75 and $30.03 per time-based option for the years ended December 31, 2011 and 2010, respectively. The total grant-date fair value of time-based options that vested was $8 million and $12 million for the years ended December 31, 2011 and 2010, respectively. There were time-based options to purchase 210,997 and 289,445 shares exercised during the years ended December 31, 2011 and 2010, respectively. The total pretax intrinsic value of time-based options exercised was $5 million and $11 million during the years ended December 31, 2011 and 2010, respectively. There were unvested time-based options to purchase 396,997 and 470,400 shares as of December 31, 2011 and 2010, respectively.

Stock appreciation rights—The following table summarizes activity for stock appreciation rights outstanding under our incentive plans during the year ended December 31, 2012:

	Number of awards	Weighted-average exercise price per share		Weighted-average remaining contractual term (years)	Aggregate intrinsic value (in millions)
Outstanding at January 1, 2012	187,739	$	93.39	4.76	$	—
Outstanding at December 31, 2012	187,739	$	93.39	3.76	$	—

Vested and exercisable at December 31, 2012	187,739	$	93.39	3.76	$	—

We did not grant stock appreciation rights during the years ended December 31, 2012, 2011, and 2010. At January 1 and December 31, 2012, we have presented the aggregate intrinsic value as zero since the weighted-average exercise price per share exceeded the market price of our shares on those dates. There were 1,400 stock appreciation rights exercised with a total pre-tax intrinsic value of zero for the year ended December 31, 2011. There were no stock appreciation rights exercised during the year ended December 31, 2010. There were no unvested stock appreciation rights outstanding as of December 31, 2012, 2011 and 2010.

Market-Based Awards

Deferred units—We grant market-based deferred units (“market-based units”) that can be earned depending on the achievement of certain market conditions. The number of units earned is quantified upon completion of the specified period at the determination date. The following table summarizes unvested activity for market-based units granted under our incentive plans during the year ended December 31, 2012:

	Number of units		Weighted-average grant-date fair value per share
Unvested at January 1, 2012	415,947		$	75.98
Granted	163,319		58.52
Vested	(318,926	)	75.18
Forfeited	(28,889	)	70.04
Unvested at December 31, 2012	231,451		$	65.50

Total grant-date fair value of the market based units that vested during the year ended December 31, 2012 was $24 million.

There were 98,797 and 122,934 market-based units granted during the years ended December 31, 2011 and 2010 with a weighted-average grant-date fair value of $78.69 and $82.55 per share, respectively. No market-based units vested in the years ended December 31, 2011 and 2010.

Performance-Based Awards

Stock options—We have previously granted performance-based stock options (“performance-based options”) that could be earned depending on the achievement of certain performance targets. The number of options earned is quantified upon completion of the performance period at the determination date. The following table summarizes activity for vested and unvested performance-based options outstanding under our incentive plans during the year ended December 31, 2012:

	Number of shares under option	Weighted-average exercise price per share		Weighted-average remaining contractual term (years)	Aggregate intrinsic value (in millions)
Outstanding at January 1, 2012	179,262	$	75.30	4.23	$	—
Outstanding at December 31, 2012	179,262	$	75.30	3.22	$	—

Vested and exercisable at December 31, 2012	179,262	$	75.30	3.22	$	—

We did not grant performance-based options during the years ended December 31, 2012, 2011 and 2010. At January 1 and December 31, 2012, we have presented the aggregate intrinsic value as zero since the weighted-average exercise price per share exceeded the market price of our shares on that date. There were no performance-based options exercised during the years ended December 31, 2012, 2011 and 2010. There were no unvested performance-based stock options outstanding as of December 31, 2012, 2011 and 2010.

- Definition

The entire disclosure for compensation-related costs for equity-based compensation, which may include disclosure of policies, compensation plan details, allocation of equity compensation, incentive distributions, equity-based arrangements to obtain goods and services, deferred compensation arrangements, employee stock ownership plan details and employee stock purchase plan details.

+ References

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-Name Statement of Financial Accounting Standard (FAS)

-Number 123R

-Paragraph 64, 65, A240

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 14

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-Name Statement of Position (SOP)

-Number 93-6

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+ Details

Supplemental Balance Sheet Information

12 Months Ended

Dec. 31, 2012

Supplemental Balance Sheet Information

Supplemental Balance Sheet Information

Note 21—Supplemental Balance Sheet Information

Other current liabilities were comprised of the following (in millions):

	December 31,
	2012		2011
Other current liabilities
Accrued payroll and employee benefits	$	421	$	328
Distribution payable	—		278
Deferred revenue	214		171
Deferred revenue of consolidated variable interest entities	21		16
Accrued taxes, other than income	150		142
Accrued interest	122		132
Contingent liabilities	1,958		1,243
Other	47		65
Total other current liabilities	$	2,933	$	2,375

Other long-term liabilities were comprised of the following (in millions):

	December 31,
	2012		2011
Other long-term liabilities
Long-term income taxes payable	$	584	$	751
Accrued pension liabilities	558		579
Deferred revenue	174		236
Deferred revenue of consolidated variable interest entities	72		85
Drilling contract intangibles	60		103
Accrued retiree life insurance and medical benefits	54		49
Other	102		122
Total other long-term liabilities	$	1,604	$	1,925

Supplemental Cash Flow Information

12 Months Ended

Dec. 31, 2012

Supplemental Cash Flow Information

Supplemental Cash Flow Information

Note 22—Supplemental Cash Flow Information

Net cash provided by operating activities attributable to the net change in operating assets and liabilities were composed of the following (in millions):

	Years ended December 31,
	2012			2011			2010
Changes in operating assets and liabilities
Decrease (increase) in accounts receivable	$	(139	)	$	(174	)	$	386
Increase in other current assets	(73		)	(73		)	(75		)
Decrease (increase) in other assets	12			26			(40		)
Increase in accounts payable and other current liabilities	931			978			197
Decrease in other long-term liabilities	(63		)	(34		)	(52		)
Change in income taxes receivable / payable, net	(156		)	80			(37		)
	$	512		$	803		$	379

Additional cash flow information were as follows (in millions):

	Years ended December 31,
	2012		2011		2010
Certain cash operating activities
Cash payments for interest	$	719	$	501	$	455
Cash payments for income taxes	347		338		493

Non-cash investing and financing activities
Capital expenditures, accrued at end of period (a)	$	123	$	62	$	66
Issuance of shares in exchange for redeemable noncontrolling interest (b)	367		—		—
Non-cash proceeds received for the sale of assets (c)	194		—		134

(a) These amounts represent additions to property and equipment for which we had accrued a corresponding liability in accounts payable.

(b) On May 31, 2012, we issued 8.7 million shares to Quantum in a non-cash exchange for its interest in TPDI. See Note 18—Redeemable Noncontrolling Interest.

(c) During the year ended December 31, 2012, we completed the sale of 38 drilling units to Shelf Drilling. In connection with the sale transactions, we received net cash proceeds of $568 million and non-cash proceeds in the form of preference shares with an aggregate stated value of $196 million. We recognized the preference shares at their estimated fair value measured at the time of the sale, in the aggregate amount of $194 million, including the fair value associated with the embedded derivatives. See Note 9—Discontinued Operations.

- Definition

The entire disclosure for supplemental cash flow activities, including cash, noncash, and part noncash transactions, for the period. Noncash is defined as information about all investing and financing activities of an enterprise during a period that affect recognized assets or liabilities but that do not result in cash receipts or cash payments in the period. "Part noncash" refers to that portion of the transaction not resulting in cash receipts or cash payments in the period.

+ References+ Details

Financial Instruments

12 Months Ended

Dec. 31, 2012

Financial Instruments

Financial Instruments

Note 23—Financial Instruments

The carrying amounts and fair values of our financial instruments were as follows:

	December 31, 2012				December 31, 2011
	Carrying amount		Fair value		Carrying amount		Fair value
Cash and cash equivalents	$	5,134	$	5,134	$	4,017	$	4,017
Notes and other loans receivable	142		142		154		154
Preference shares	196		196		—		—
Restricted cash investments	857		903		934		975
Long-term debt, including current maturities	12,268		13,899		12,698		13,074
Long-term debt of consolidated variable interest entities, including current maturities	191		191		838		838
Derivative instruments, assets	8		8		36		36
Derivative instruments, liabilities	15		15		38		38

We estimated the fair value of each class of financial instruments, for which estimating fair value is practicable, by applying the following methods and assumptions:

Cash and cash equivalents—The carrying amount of cash and cash equivalents, which are stated at cost plus accrued interest, approximates fair value because of the short maturities of those instruments.

Notes and other loans receivable—We hold certain notes and other loans receivable, which originated in connection with certain asset dispositions and supplier advances. The aggregate carrying amount represents the amortized cost of our investments, which approximates the estimated fair value. We measured the estimated fair value using significant unobservable inputs, representative of a Level 3 fair value measurement, including the credit ratings of the borrowers. At December 31, 2012, the aggregate carrying amount of our notes receivable and other loans receivable was $142 million, including $35 million and $107 million recorded in other current assets and other assets, respectively. At December 31, 2011, the aggregate carrying amount of our notes receivable and other loans receivable was $154 million, including $37 million and $117 million, recorded in other current assets and other assets, respectively.

Preference shares—In connection with our sale of 38 drilling units to Shelf Drilling, we received preference shares of one of its intermediate parent companies. The aggregate carrying amount of the preference shares represents the historical cost of our investment, as the preference shares do not have a readily determinable fair value. We measured the estimated fair value of the Shelf Drilling preference shares using significant unobservable inputs, representative of a Level 3 fair value measurement, including the credit ratings and financial position of the investee. At December 31, 2012, the aggregate carrying amount of the preference shares, excluding the balance associated with the embedded derivatives, was $196 million, recorded in other assets.

Restricted cash investments—The carrying amount of the Aker Restricted Cash Investments represents the amortized cost of our investment, which was $797 million and $889 million at December 31, 2012 and 2011, respectively. We measured the estimated fair value of the Aker Restricted Investments using significant other observable inputs, representative of a Level 2 fair value measurement, including the terms and credit spreads of the instruments. At December 31, 2012 and 2011, the estimated fair value of the Aker Restricted Cash Investments was $843 million and $930 million, respectively.

The aggregate carrying amount of the restricted cash investments for the TPDI Credit Facilities, the ADDCL Credit Facilities and other obligations approximates fair value due to the short term nature of the instruments in which the restricted cash investments are held. At December 31, 2012 and 2011, the aggregate carrying amount of the restricted cash investments for the TPDI Credit Facilities, the ADDCL Credit Facilities and other obligations was $60 million and $45 million, respectively.

Debt—The aggregate carrying amount of our fixed-rate debt was $11.7 billion and $11.9 billion at December 31, 2012 and 2011, respectively. We measured the estimated fair value of our fixed-rate debt using significant other observable inputs, representative of a Level 2 fair value measurement, including the terms and credit spreads for the instruments. At December 31, 2012 and 2011, the aggregate estimated fair value of our fixed-rate debt was $13.3 billion and $12.2 billion, respectively.

The aggregate carrying amount of our variable-rate debt approximates fair value because the terms of those debt instruments include short-term interest rates and exclude penalties for prepayment. We measured the estimated fair value of our variable-rate debt using significant other observable inputs, representative of a Level 2 fair value measurement, including the terms and credit spreads for the instruments. At December 31, 2012 and 2011, the aggregate carrying amount of our variable-rate debt was $579 million and $761 million, respectively.

Debt of consolidated variable interest entities—The aggregate carrying amount of the variable-rate debt of our consolidated variable interest entities approximates fair value because the terms of those debt instruments include short-term interest rates and exclude penalties for prepayments. We measured the estimated fair value of the debt of our consolidated variable interest entities using significant other observable inputs, representative of a Level 2 fair value measurement, including the terms and credit spreads of the instruments. At December 31, 2012 and 2011, the aggregate carrying amount of the variable-rate debt of our consolidated variable interest entities was $191 million and $838 million, respectively.

Derivative instruments—The aggregate carrying amount of our derivative instruments represents the estimated fair value. We measured the estimated fair value using significant other observable inputs, representative of a Level 2 fair value measurement, including the interest rates and terms of the instruments.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 107

-Paragraph 3, 10, 14, 15

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+ Details

Risk Concentration	12 Months Ended
Risk Concentration	Dec. 31, 2012
Risk Concentration
Risk Concentration	Note 24—Risk Concentration Interest rate risk—Financial instruments that potentially subject us to concentrations of interest rate risk include our cash equivalents, short-term investments, restricted cash investments, debt and capital lease obligations. We are exposed to interest rate risk related to our cash equivalents and short-term investments, as the interest income earned on these investments changes with market interest rates. Floating rate debt, where the interest rate may be adjusted annually or more frequently over the life of the instrument, exposes us to short-term changes in market interest rates. Fixed rate debt, where the interest rate is fixed over the life of the instrument and the instrument’s maturity is greater than one year, exposes us to changes in market interest rates when we refinance maturing debt with new debt. Our fixed-rate restricted cash investments, acquired in connection with our acquisition of Aker Drilling, and the respective debt instruments for which they are restricted, are subject to corresponding and opposing changes in the fair value relative to changes in market interest rates. From time to time, we may use interest rate swap agreements to manage the effect of interest rate changes on future income. We do not generally enter into interest rate derivative transactions for speculative or trading purposes. Interest rate swaps are generally designated as hedges of underlying future interest payments. These agreements involve the exchange of amounts based on variable interest rates and amounts based on a fixed interest rate over the life of the agreement without an exchange of the notional amount upon which the payments are based. The interest rate differential to be received or paid on the swaps is recognized over the lives of the swaps as an adjustment to interest expense. Gains and losses on terminations of interest rate swap agreements are deferred and recognized as an adjustment to interest expense over the remaining life of the underlying debt. In the event of the early retirement of a designated debt obligation, any realized or unrealized gain or loss from the swap would be recognized in income. Currency exchange rate risk—Our international operations expose us to currency exchange rate risk. This risk is primarily associated with compensation costs of our employees and purchasing costs from non-U.S. suppliers, which are denominated in currencies other than the U.S. dollar. We use a variety of techniques to minimize the exposure to currency exchange rate risk, including the structuring of customer contract payment terms and, from time to time, the use of foreign exchange derivative instruments. Our primary currency exchange rate risk management strategy involves structuring customer contracts to provide for payment in both U.S. dollars and local currency. The payment portion denominated in local currency is based on anticipated local currency requirements over the contract term. Due to various factors, including customer acceptance, local banking laws, other statutory requirements, local currency convertibility and the impact of inflation on local costs, actual local currency needs may vary from those anticipated in the customer contracts, resulting in partial exposure to currency exchange rate risk. The currency exchange effect resulting from our international operations generally has not had a material impact on our operating results. In situations where payments of local currency do not equal local currency requirements, we may use currency exchange derivative instruments, specifically forward exchange contracts, or spot purchases, to mitigate currency exchange rate risk. A forward exchange contract obligates us to exchange predetermined amounts of specified foreign currencies at specified currency exchange rates on specified dates or to make an equivalent U.S. dollar payment equal to the value of such exchange. We do not enter into currency exchange derivative transactions for speculative purposes. We record designated currency exchange derivative instruments at fair value and defer gains and losses in other comprehensive income, recognizing the gains and losses when the underlying currency exchange exposure is realized. We record undesignated currency exchange derivative instruments at fair value and record changes to the fair value in current period earnings as an adjustment to currency exchange gains or losses. At December 31, 2012 and 2011, we had cross-currency swaps, assumed in connection with our acquisition of Aker Drilling, that were designated as cash flow hedges of certain debt instruments denominated in Norwegian kroner. Credit risk—Financial instruments that potentially subject us to concentrations of credit risk are primarily cash and cash equivalents, short-term investments, trade receivables, notes and loans receivable and equity investment. We generally maintain our cash and cash equivalents in time deposits at commercial banks with high credit ratings or mutual funds, which invest exclusively in high-quality money market instruments. We limit the amount of exposure to any one institution and do not believe we are exposed to any significant credit risk. We derive the majority of our revenue from services to international oil companies, government-owned oil companies and government-controlled oil companies. Receivables are dispersed in various countries (see Note 25—Operating Segments, Geographic Analysis and Major Customers). We maintain an allowance for doubtful accounts receivable based upon expected collectability and establish reserves for doubtful accounts on a case-by-case basis when we believe the payment of specific amounts owed to us is unlikely to occur. Although we have encountered isolated credit concerns related to independent oil companies, we are not aware of any significant credit risks related to our customer base and do not generally require collateral or other security to support customer receivables. We hold investments in debt and equity instruments of certain privately held companies as a result of certain dispositions of assets and equity interests or as a result of arrangements with certain suppliers. We monitor the financial condition of the investees on an ongoing basis to determine whether a valuation allowance is required. Labor agreements—We require highly skilled personnel to operate our drilling units. We conduct extensive personnel recruiting, training and safety programs. At December 31, 2012, we had approximately 18,400 employees, including approximately 1,700 persons engaged through contract labor providers. Of our 18,400 employees, approximately 3,000 persons are working under operating agreements with Shelf Drilling and are expected to transition upon expiration of such operating agreements. Some of our employees working in Angola, the U.K., Nigeria, Norway, Australia and Brazil are represented by, and some of our contracted labor work under, collective bargaining agreements. Many of these represented individuals are working under agreements that are subject to annual salary negotiation. These negotiations could result in higher personnel expenses, other increased costs or increased operational restrictions as the outcome of such negotiations apply to all offshore employees not just the union members.

- Definition

The entire disclosure for any concentrations existing at the date of the financial statements that make an entity vulnerable to a reasonably possible, near-term, severe impact. This disclosure informs financial statement users about the general nature of the risk associated with the concentration, and may indicate the percentage of concentration risk as of the balance sheet date.

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+ Details

Operating Segments, Geographic Analysis and Major Customers

12 Months Ended

Dec. 31, 2012

Operating Segments, Geographic Analysis and Major Customers

Operating Segments, Geographic Analysis and Major Customers

Note 25—Operating Segments, Geographic Analysis and Major Customers

Operating segments—We have established two operating segments: (1) contract drilling services and (2) drilling management services. Our contract drilling services business operates in a single, global market for the provision of contract drilling services. The location of our rigs and the allocation of our resources to build or upgrade rigs are determined by the activities and needs of our customers. Our drilling management services operating segment does not meet the quantitative thresholds for determining reportable segments.

Geographic analysis—Operating revenues for our continuing operations by country were as follows (in millions):

	Years ended December 31,
	2012		2011		2010
Operating revenues
U.S.	$	2,472	$	1,971	$	1,937
Norway	1,174		897		765
Brazil	1,114		1,019		1,288
U.K.	1,028		1,099		1,097
Other countries (a)	3,408		3,041		2,862
Total operating revenues	$	9,196	$	8,027	$	7,949

(a) Other countries represents countries in which we operate that individually had operating revenues representing less than 10 percent of total operating revenues earned.

Long-lived assets by country were as follows (in millions):

	December 31,
	2012		2011
Long-lived assets
U.S.	$	7,395	$	6,553
Brazil	2,285		2,185
Norway	2,072		2,067
Other countries (a)	9,128		9,983
Total long-lived assets	$	20,880	$	20,788

(a) Other countries represents countries in which we operate that individually had long-lived assets representing less than 10 percent of total long-lived assets.

A substantial portion of our assets are mobile. Asset locations at the end of the period are not necessarily indicative of the geographic distribution of the revenues generated by such assets during the periods. Although we are organized under the laws of Switzerland, we do not conduct any operations and do not have operating revenues in Switzerland. At December 31, 2012 and 2011, the aggregate carrying amount of our long-lived assets located in Switzerland was $7 million and $8 million, respectively.

Our international operations are subject to certain political and other uncertainties, including risks of war and civil disturbances or other market disrupting events, expropriation of equipment, repatriation of income or capital, taxation policies, and the general hazards associated with certain areas in which we operate.

Major customers—For the year ended December 31, 2012, Chevron Corporation, BP and Petrobras accounted for approximately 11 percent, 11 percent and 10 percent, respectively, of our consolidated operating revenues from continuing operations. For the year ended December 31, 2011, BP accounted for approximately 11 percent of our consolidated operating revenues from continuing operations. For the year ended December 31, 2010, BP and Petrobras each accounted for approximately 11 percent of our consolidated operating revenues from continuing operations.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

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+ Details

Condensed Consolidating Financial Information

12 Months Ended

Dec. 31, 2012

Condensed Consolidating Financial Information

Condensed Consolidating Financial Information

Note 26—Condensed Consolidating Financial Information

Transocean Inc., a wholly owned subsidiary of Transocean Ltd., is the issuer of certain notes and debentures, which have been guaranteed by Transocean Ltd. Transocean Ltd.’s guarantee of debt securities of Transocean Inc. is full and unconditional. Transocean Ltd. is not subject to any significant restrictions on its ability to obtain funds from its consolidated subsidiaries or entities accounted for under the equity method by dividends, loans or return of capital distributions.

The following tables present condensed consolidating financial information for (a) Transocean Ltd. (the “Parent Guarantor”), (b) Transocean Inc. (the “Subsidiary Issuer”), and (c) the other direct and indirect wholly owned and partially owned subsidiaries of the Parent Guarantor, none of which guarantee any indebtedness of the Subsidiary Issuer (the “Other Subsidiaries”), as well as (d) the consolidating adjustments necessary to present the condensed financial statements on a consolidated basis. The condensed consolidating financial information may not necessarily be indicative of the results of operations, financial position or cash flows had the subsidiaries operated as independent entities.

	Year ended December 31, 2012
	Parent Guarantor			Subsidiary Issuer			Other Subsidiaries			Consolidating adjustments			Consolidated
							(in millions)
Operating revenues	$	—		$	5		$	9,213		$	(22	)	$	9,196
Cost and expenses	54			16			7,463			(22		)	7,511
Loss on impairment	—			—			(140		)	—			(140		)
Gain on disposal of assets, net	—			—			36			—			36
Operating income (loss)	(54		)	(11		)	1,646			—			1,581

Other income (expense), net
Interest expense, net	(12		)	(576		)	(79		)	—			(667		)
Equity in earnings	(153		)	402			—			(249		)	—
Other, net	—			(4		)	(44		)	—			(48		)
	(165		)	(178		)	(123		)	(249		)	(715		)
Income (loss) from continuing operations before income tax expense	(219		)	(189		)	1,523			(249		)	866
Income tax expense	—			—			50			—			50
Income (loss) from continuing operations	(219		)	(189		)	1,473			(249		)	816
Loss from discontinued operations, net of tax	—			—			(1,027		)	—			(1,027		)

Net income (loss)	(219		)	(189		)	446			(249		)	(211		)
Net income (loss) attributable to noncontrolling interest	—			—			8			—			8
Net income (loss) attributable to controlling interest	(219		)	(189		)	438			(249		)	(219		)

Other comprehensive income (loss) before income taxes	(5		)	(31		)	35			—			(1		)
Income taxes related to other comprehensive income (loss)	—			—			(7		)	—			(7		)
Other comprehensive income (loss), net of income taxes	(5		)	(31		)	28			—			(8		)

Total comprehensive income (loss)	(224		)	(220		)	474			(249		)	(219		)
Total comprehensive income (loss) attributable to noncontrolling interest	—			—			8			—			8
Total comprehensive income (loss) attributable to controlling interest	$	(224	)	$	(220	)	$	466		$	(249	)	$	(227	)

	Year ended December 31, 2011
	Parent Guarantor			Subsidiary Issuer			Other Subsidiaries			Consolidating adjustments			Consolidated

Operating revenues	$	—		$	—		$	8,045		$	(18	)	$	8,027
Cost and expenses	44			4			7,546			(18		)	7,576
Loss on impairment	—			—			(5,201		)	—			(5,201		)
Loss on disposal of assets, net	—			—			(12		)	—			(12		)
Operating loss	(44		)	(4		)	(4,714		)	—			(4,762		)

Other income (expense), net
Interest expense, net	(11		)	(510		)	(56		)	—			(577		)
Equity in earnings	(5,699		)	(5,174		)	—			10,873			—
Other, net	—			9			(108		)	—			(99		)
	(5,710		)	(5,675		)	(164		)	10,873			(676		)
Loss from continuing operations before income tax expense	(5,754		)	(5,679		)	(4,878		)	10,873			(5,438		)
Income tax expense	—			—			324			—			324
Loss from continuing operations	(5,754		)	(5,679		)	(5,202		)	10,873			(5,762		)
Income from discontinued operations, net of tax	—			—			85			—			85

Net loss	(5,754		)	(5,679		)	(5,117		)	10,873			(5,677		)
Net income attributable to noncontrolling interest	—			—			77			—			77
Net loss attributable to controlling interest	(5,754		)	(5,679		)	(5,194		)	10,873			(5,754		)

Other comprehensive income (loss) before income taxes	(3		)	(114		)	(64		)	—			(181		)
Income taxes related to other comprehensive income (loss)	—			—			13			—			13
Other comprehensive income (loss), net of income taxes	(3		)	(114		)	(51		)	—			(168		)

Total comprehensive income (loss)	(5,757		)	(5,793		)	(5,168		)	10,873			(5,845		)
Total comprehensive income attributable to noncontrolling interest	—			—			73			—			73
Total comprehensive income (loss) attributable to controlling interest	$	(5,757	)	$	(5,793	)	$	(5,241	)	$	10,873		$	(5,918	)

	Year ended December 31, 2010
	Parent Guarantor			Subsidiary Issuer			Other Subsidiaries			Consolidating adjustments			Consolidated

Operating revenues	$	—		$	—		$	7,964		$	(15	)	$	7,949
Cost and expenses	45			3			5,441			(15		)	5,474
Gain on disposal of assets, net	—			—			255			—			255
Operating income (loss)	(45		)	(3		)	2,778			—			2,730

Other income (expense), net
Interest expense, net	1			(494		)	(51		)	—			(544		)
Equity in earnings	970			1,484			—			(2,454		)	—
Other, net	—			(7		)	(24		)	—			(31		)
	971			983			(75		)	(2,454		)	(575		)
Income from continuing operations before income tax expense	926			980			2,703			(2,454		)	2,155
Income tax expense	—			—			292			—			292
Income from continuing operations	926			980			2,411			(2,454		)	1,863
Loss from discontinued operations, net of tax	—			—			(894		)	—			(894		)

Net income	926			980			1,517			(2,454		)	969
Net income attributable to noncontrolling interest	—			—			43			—			43
Net income attributable to controlling interest	926			980			1,474			(2,454		)	926

Other comprehensive income (loss) before income taxes	7			(44		)	28			—			(9		)
Income taxes related to other comprehensive income (loss)	—			—			(9		)	—			(9		)
Other comprehensive income (loss), net of income taxes	7			(44		)	19			—			(18		)

Total comprehensive income	933			936			1,536			(2,454		)	951
Total comprehensive income attributable to noncontrolling interest	—			—			22			—			22
Total comprehensive income attributable to controlling interest	$	933		$	936		$	1,514		$	(2,454	)	$	929

	December 31, 2012
	Parent Guarantor		Subsidiary Issuer		Other Subsidiaries		Consolidating adjustments			Consolidated

Assets
Cash and cash equivalents	$	24	$	3,155	$	1,955	$	—		$	5,134
Other current assets	7		1,901		3,852		(2,247		)	3,513
Total current assets	31		5,056		5,807		(2,247		)	8,647

Property and equipment, net	—		—		20,880		—			20,880
Goodwill	—		—		2,987		—			2,987
Investment in affiliates	16,354		27,933		196		(44,287		)	196
Other assets	—		1,804		18,048		(18,307		)	1,545
Total assets	16,385		34,793		47,918		(64,841		)	34,255

Liabilities and equity
Debt due within one year	—		564		803		—			1,367
Other current liabilities	13		632		5,698		(2,247		)	4,096
Total current liabilities	13		1,196		6,501		(2,247		)	5,463

Long-term debt	594		17,772		11,033		(18,307		)	11,092
Other long-term liabilities	33		454		1,483		—			1,970
Total long-term liabilities	627		18,226		12,516		(18,307		)	13,062

Commitments and contingencies
Redeemable noncontrolling interest	—		—		—		—			—

Total equity	15,745		15,371		28,901		(44,287		)	15,730
Total liabilities and equity	$	16,385	$	34,793	$	47,918	$	(64,841	)	$	34,255

	December 31, 2011
	Parent Guarantor		Subsidiary Issuer		Other Subsidiaries		Consolidating adjustments			Consolidated

Assets
Cash and cash equivalents	$	3	$	2,793	$	1,221	$	—		$	4,017
Other current assets	8		784		4,476		(1,749		)	3,519
Total current assets	11		3,577		5,697		(1,749		)	7,536

Property and equipment, net	1		—		20,787		—			20,788
Goodwill	—		—		3,217		—			3,217
Investment in affiliates	16,439		27,518		—		(43,957		)	—
Other assets	—		1,368		20,799		(18,676		)	3,491
Total assets	16,451		32,463		50,500		(64,382		)	35,032

Liabilities and equity
Debt due within one year	—		1,693		494		—			2,187
Other current liabilities	294		367		4,429		(1,749		)	3,341
Total current liabilities	294		2,060		4,923		(1,749		)	5,528

Long-term debt	495		14,308		15,222		(18,676		)	11,349
Other long-term liabilities	25		439		1,948		—			2,412
Total long-term liabilities	520		14,747		17,170		(18,676		)	13,761

Commitments and contingencies
Redeemable noncontrolling interest	—		—		116		—			116

Total equity	15,637		15,656		28,291		(43,957		)	15,627
Total liabilities and equity	$	16,451	$	32,463	$	50,500	$	(64,382	)	$	35,032

	Year ended December 31, 2012
	Parent Guarantor			Subsidiary Issuer			Other Subsidiaries			Consolidating adjustments			Consolidated

Cash flows from operating activities	$	(86	)	$	(953	)	$	3,747		$	—		$	2,708

Cash flows from investing activities
Capital expenditures	—			—			(1,303		)	—			(1,303		)
Capital expenditures for discontinued operations	—			—			(106		)	—			(106		)
Proceeds from disposal of assets, net	—			—			191			—			191
Proceeds from disposal of discontinued operations, net	—			568			221			—			789
Investing activities with affiliates, net	(165		)	(2,344		)	(3,726		)	6,235			—
Other, net	—			29			11			—			40
Net cash provided by (used in) investing activities	(165		)	(1,747		)	(4,712		)	6,235			(389		)

Cash flows from financing activities
Changes in short-term borrowings, net	—			—			(260		)	—			(260		)
Proceeds from debt	—			1,493			—			—			1,493
Repayments of debt	—			(1,689		)	(593		)	—			(2,282		)
Proceeds from restricted cash investments	—			—			311			—			311
Deposits to restricted cash investments	—			—			(167		)	—			(167		)
Distribution of qualifying additional paid-in capital	(278		)	—			—			—			(278		)
Financing activities with affiliates, net	549			3,276			2,410			(6,235		)	—
Other, net	1			(18		)	(2		)	—			(19		)
Net cash provided by (used in) financing activities	272			3,062			1,699			(6,235		)	(1,202		)

Net increase (decrease) in cash and cash equivalents	21			362			734			—			1,117
Cash and cash equivalents at beginning of period	3			2,793			1,221			—			4,017
Cash and cash equivalents at end of period	$	24		$	3,155		$	1,955		$	—		$	5,134

	Year ended December 31, 2011
	Parent Guarantor			Subsidiary Issuer			Other Subsidiaries			Consolidating adjustments			Consolidated

Cash flows from operating activities	$	(52	)	$	(568	)	$	2,445		$	—		$	1,825

Cash flows from investing activities
Capital expenditures	—			—			(974		)	—			(974		)
Capital expenditures for discontinued operations	—			—			(46		)	—			(46		)
Investment in business combination, net of cash acquired	—			—			(1,246		)	—			(1,246		)
Proceeds from disposal of assets, net	—			—			14			—			14
Proceeds from disposal of discontinued operations, net	—			—			447			—			447
Investing activities with affiliates, net	(875		)	(325		)	(1,764		)	2,964			—
Other, net	—			(23		)	(68		)	—			(91		)
Net cash provided by (used in) investing activities	(875		)	(348		)	(3,637		)	2,964			(1,896		)

Cash flows from financing activities
Changes in short-term borrowings, net	—			(88		)	—			—			(88		)
Proceeds from debt	435			2,504			—			—			2,939
Repayments of debt	(429		)	(1,827		)	(153		)	—			(2,409		)
Proceeds from restricted cash investments	429			—			50			—			479
Deposits to restricted cash investments	(435		)	—			(88		)	—			(523		)
Proceeds from share issuance, net	1,211			—			—			—			1,211
Distribution of qualifying additional paid-in capital	(763		)	—			—			—			(763		)
Financing activities with affiliates, net	495			1,114			1,355			(2,964		)	—
Other, net	(51		)	(35		)	(26		)	—			(112		)
Net cash provided by (used in) financing activities	892			1,668			1,138			(2,964		)	734

Net increase (decrease) in cash and cash equivalents	(35		)	752			(54		)	—			663
Cash and cash equivalents at beginning of period	38			2,041			1,275			—			3,354
Cash and cash equivalents at end of period	$	3		$	2,793		$	1,221		$	—		$	4,017

	Year ended December 31, 2010
	Parent Guarantor			Subsidiary Issuer			Other Subsidiaries			Consolidating adjustments			Consolidated

Cash flows from operating activities	$	(33	)	$	(358	)	$	4,297		$	—		$	3,906

Cash flows from investing activities
Capital expenditures	(4		)	—			(1,345		)	—			(1,349		)
Capital expenditures for discontinued operations	—			—			(42		)	—			(42		)
Proceeds from disposal of assets, net	—			—			60			—			60
Proceeds from insurance recoveries for loss of drilling unit	—			—			560			—			560
Investing activities with affiliates, net	310			1,357			(1,694		)	27			—
Other, net	—			(6		)	56			—			50
Net cash provided by (used in) investing activities	306			1,351			(2,405		)	27			(721		)

Cash flows from financing activities
Changes in short-term borrowings, net	—			(193		)	—			—			(193		)
Proceeds from debt	—			1,999			55			—			2,054
Repayments of debt	—			(2,245		)	(320		)	—			(2,565		)
Purchases of shares held in treasury	(240		)	—			—			—			(240		)
Financing activities with affiliates, net	—			1,384			(1,357		)	(27		)	—
Other, net	—			(14		)	(3		)	—			(17		)
Net cash provided by (used in) financing activities	(240		)	931			(1,625		)	(27		)	(961		)

Net increase in cash and cash equivalents	33			1,924			267			—			2,224
Cash and cash equivalents at beginning of period	5			117			1,008			—			1,130
Cash and cash equivalents at end of period	$	38		$	2,041		$	1,275		$	—		$	3,354

Related Party Transactions	12 Months Ended
Related Party Transactions	Dec. 31, 2012
Related Party Transactions
Related Party Transactions	Note 27—Related Party Transactions Quantum Pacific Management Limited—On October 18, 2007, one of our subsidiaries acquired a 50 percent interest in TPDI, an entity formed to operate two Ultra-Deepwater Floaters, Dhirubhai Deepwater KG1 and Dhirubhai Deepwater KG2. Until May 31, 2012, Quantum held the remaining 50 percent interest in TPDI. We presented Quantum’s interest in TPDI as redeemable noncontrolling interest on our consolidated balance sheets since Quantum had the unilateral right to exchange its interest in TPDI for our shares or cash, at its election, measured at an amount based on an appraisal of the fair value of the drillships that are owned by TPDI, subject to certain adjustments. On February 29, 2012, Quantum exercised its rights under a put option agreement to exchange its interest in TPDI for our shares or cash, at its election. On March 29, 2012, Quantum elected to exchange its interest in TPDI for our shares, net of Quantum’s share of TPDI’s indebtedness, as defined in the put option agreement. Quantum had the right, prior to closing of this exchange, to change its election to cash, net of Quantum’s share of TPDI’s indebtedness. On May 31, 2012, we issued 8.7 million shares to Quantum in a non-cash exchange for its interest in TPDI, and as a result, TPDI became our wholly owned subsidiary. The put option agreement, among other things, restricts Quantum’s sale of our shares until May 29, 2013. In August 2012, we paid $72 million as the final cash settlement, representing 50 percent of TPDI’s working capital at May 29, 2012. See Note 18—Redeemable Noncontrolling Interest.

- Definition

The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Name Statement of Financial Accounting Standard (FAS)

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Quarterly Results (Unaudited)

12 Months Ended

Dec. 31, 2012

Quarterly Results (Unaudited)

Quarterly Results (Unaudited)

Note 28—Quarterly Results (Unaudited)

Shown below are selected unaudited quarterly data. Amounts have been restated to reflect corrections of errors identified in previously reported amounts (see Note 4—Correction of Errors in Previously Reported Consolidated Financial Statements) and to reflect reclassifications associated with our discontinued operations (see Note 9—Discontinued Operations).

	Three months ended
	March 31,		June 30,			September 30,			December 31,
	(In millions, except per share data)
2012
Operating revenues	$	2,110	$	2,329		$	2,431		$	2,326
Operating income (loss) (a)	371		(142		)	811			541
Income (loss) from continuing operations	154		(303		)	533			432
Net income (loss) attributable to controlling interest (a) (b)	10		(304		)	(381		)	456
Per share earnings (loss) from continuing operations
Basic	$	0.42	$	(0.86	)	$	1.49		$	1.19
Diluted	$	0.42	$	(0.86	)	$	1.49		$	1.19
Weighted-average shares outstanding
Basic	350		353			359			359
Diluted	350		353			359			360

2011
Operating revenues	$	1,869	$	2,051		$	1,974		$	2,133
Operating income (loss) (c)	366		380			303			(5,811		)
Income (loss) from continuing operations	180		171			(19		)	(6,094		)
Net income (loss) attributable to controlling interest (c) (d)	319		124			(32		)	(6,165		)
Per share earnings (loss) from continuing operations
Basic	$	0.51	$	0.51		$	(0.09	)	$	(18.67	)
Diluted	$	0.51	$	0.50		$	(0.09	)	$	(18.67	)
Weighted-average shares outstanding
Basic	319		320			320			329
Diluted	320		320			320			329

(a) First quarter included an adjustment of $118 million to our goodwill impairment associated with our contract drilling reporting unit and an impairment of $22 million of the customer relationships intangible asset associated with the U.K. operations of our drilling management services reporting unit. Second quarter included an estimated loss of $750 million in connection with loss contingencies associated with the Macondo well incident. Third quarter included an aggregate gain of $51 million associated with the sale of Discoverer 534 and Jim Cunningham. See Note 7—Intangible Asset Impairments, Note 12—Drilling Fleet and Note 17—Commitments and Contingencies.

(b) First, second, third and fourth quarters included gains (losses) on disposal of discontinued operations in the amount of $(1) million, $72 million. $(1) million and $12 million, respectively. See Note 9—Discontinued Operations.

(c) Third quarter included a loss of $78 million on a forward exchange contract. Fourth quarter included an estimated loss of $5.2 billion on impairment of goodwill and an estimated loss of $1.0 billion in connection with loss contingencies associated with the Macondo well incident. See Note 7—Intangible Asset Impairments and Note 17—Commitments and Contingencies.

(d) First, second, third and fourth quarters included gains (losses) on disposal of discontinued operations in the amount of $178 million, $(2) million, $(1) million and $8 million, respectively. See Note 9—Discontinued Operations.

- Definition

The entire disclosure for the quarterly financial data in the annual financial statements. The disclosure may include a tabular presentation of financial information for each fiscal quarter for the current and previous year, including revenues, gross profit, income or loss before extraordinary items and earnings per share data. It also includes an indication if the information in the note is unaudited, comments on the aggregate effect of year-end adjustments, and an explanation of matters or transactions that affect comparability or are pertinent to an understanding of the information furnished.

+ References+ Details

Subsequent Events	12 Months Ended
Subsequent Events	Dec. 31, 2012
Subsequent Events
Subsequent Events	Note 29—Subsequent Events Discontinued operations—Subsequent to December 31, 2012, we completed the sale of the Standard Jackups D.R. Stewart and GSF Adriatic VIII. At December 31, 2012, the rigs and related equipment were classified as held for sale and had an aggregate carrying amount of $45 million. Debt—Subsequent to December 31, 2012, we redeemed the remaining $62 million aggregate principal amount of the Series C Convertible Senior Notes. We also repaid the outstanding $250 million aggregate principal amount of the 5% Notes due February 2013 as of the stated maturity date. Additionally, subsequent to December 31, 2012, we provided notice of our intent to redeem the Callable Bonds on March 6, 2013. At December 31, 2012, the aggregate principal amounts of the FRN Callable Bonds and the 11% Callable Bonds were NOK 940 million and NOK 560 million, equivalent to $169 million and $101 million, respectively, using an exchange rate of NOK 5.56 to $1.00. Macondo well incident—U.S. Department of Justice claims—Subsequent to December 31, 2012, we reached agreement with the DOJ to resolve certain outstanding civil and potential criminal charges against us arising from the Macondo well incident. As part of this resolution, we agreed to pay $1.4 billion in fines, recoveries and civil penalties, excluding interest, in scheduled payments over a five-year period through 2017. Pursuant to the Plea Agreement, one of our subsidiaries pled guilty to one misdemeanor count of negligently discharging oil into the U.S. Gulf of Mexico, in violation of the CWA. The court accepted the guilty plea on February 14, 2013 and imposed the agreed-upon sentence. Pursuant to the Plea Agreement, the court imposed a criminal fine of $100 million to be paid within 60 days of sentencing, and also entered an order requiring us to pay a total of $150 million to the National Fish & Wildlife Foundation, as follows: $58 million within 60 days of sentencing, $53 million within one year of sentencing and an additional $39 million within two years of sentencing. Such order also requires us to pay $150 million to the National Academy of Sciences as follows: $2 million within 90 days of sentencing, $7 million within one year of sentencing, $21 million within two years of sentencing, $60 million within three years of sentencing and a final payment of $60 million within four years of sentencing. As of the date of the court approval, these obligations were reclassified from other current liabilities to debt or debt due within one year on our consolidated balance sheets. Our subsidiary has also agreed to five years of probation. The DOJ has agreed, subject to the provisions of the Plea Agreement, not to further prosecute us for certain conduct generally regarding matters under investigation by the DOJ’s Deepwater Horizon Task Force. In addition, we have agreed to continue to cooperate with the Deepwater Horizon Task Force in any ongoing investigation related to or arising from the accident. Pursuant to the Consent Decree, we agreed to pay a civil penalty totaling $1.0 billion, plus interest, according to the following schedule: (a) $400 million, plus interest, within 60 days after the date of entry; (b) $400 million, plus interest, within one year after the date of entry; and (c) $200 million, plus interest, within two years after the date of entry. Such interest will accrue from January 3, 2013 at the statutory post-judgment interest rate equal to the weekly average one-year constant maturity U.S. Treasury yield, as published by the Board of Governors of the Federal Reserve System, for the calendar week preceding the date of entry, plus 2.0 percent. The Consent Decree was approved by the court on February 19, 2013, and at the time of such approval, the noncurrent portion of these obligations were reclassified to other long-term liabilities on our consolidated balance sheets. On February 25, 2013, we reached an administrative agreement (the “EPA Agreement”) with the EPA. The EPA Agreement resolves all matters relating to suspension, debarment and statutory disqualification arising from the matters contemplated by the Plea Agreement. Subject to our compliance with the terms of the EPA Agreement, the EPA has agreed that it will not suspend, debar or statutorily disqualify us and will lift any existing suspension, debarment or statutory disqualification. In the EPA Agreement, we agreed to, among other things, (1) comply with our obligations under the Plea Agreement and the Consent Decree; (2) continue the implementation of certain programs and systems, including the scheduled revision of our environmental management system and maintenance of certain compliance and ethics programs; (3) comply with certain employment and contracting procedures; (4) engage independent compliance auditors and a process safety consultant to, among other things, assess and report to the EPA on our compliance with the terms of the Plea Agreement, the Consent Decree and the EPA Agreement; and (5) give reports and notices with respect to various matters, including those relating to compliance, misconduct, legal proceedings, audit reports, the EPA Agreement, Consent Decree and Plea Agreement. Subject to certain exceptions, the EPA Agreement prohibits us from entering into or engaging in certain business relationships with individuals or entities that are debarred, suspended, proposed for debarment or similarly restricted. The EPA Agreement has a five-year term. In addition, we agreed to take specified actions relating to operations in U.S. waters, including, among other things, the design and implementation of, and compliance with, additional systems and procedures; blowout preventer certification and reports; measures to strengthen well control competencies, drilling monitoring, recordkeeping, incident reporting, risk management and oil spill training, exercises and response planning; communication with operators; alarm systems; transparency and responsibility for matters relating to the Consent Decree; and technology innovation, with a first emphasis on more efficient, reliable blowout preventers. We have agreed to submit a performance plan (the “Performance Plan”) for approval by the U.S. within 120 days after the date of entry of the Consent Decree. The Performance Plan will include, among other things, interim milestones for actions in specified areas and a proposed schedule for reports required under the Consent Decree. The Consent Decree also provides for the appointment of (i) an independent auditor to review, audit and report on our compliance with the injunctive provisions of the Consent Decree and (ii) an independent process safety consultant to review, report on and assist with respect to the process safety aspects of the Consent Decree, including operational risk identification and risk management. The Consent Decree requires certain plans, reports and submissions be made and be acceptable to the U.S. and also requires certain publicly available filings. Under the terms of the Consent Decree, the U.S. has agreed not to sue Transocean Ltd., Transocean Inc. and certain of our subsidiaries and certain related individuals for civil or administrative penalties for the Macondo well incident under specified provisions of the CWA, the Outer Continental Shelf Lands Act (“OSCLA”), the Endangered Species Act, the Marine Mammal Protection Act, the National Marine Sanctuaries Act, the federal Oil and Gas Royalty Management Act, the CERCLA, the Emergency Planning and Community Right to Know Act and the Clean Air Act. In addition, the Consent Decree resolves our appeal of the incidents of noncompliance under the OSCLA issued by the BSEE on October 12, 2011 without any admission of liability by us. The Consent Decree does not resolve the rights of the U.S. with respect to all other matters, including certain liabilities under the OPA for removal costs or natural resources damages. However, the district court previously held that we are not liable under the OPA for damages caused by subsurface discharge from the Macondo well. If this ruling is upheld on appeal, our natural resources damage assessment liability would be limited to any such damages arising from the above-surface discharge. The resolution with the DOJ of such civil and criminal claims, as discussed, does not include potential claims arising from the False Claims Act investigation. As part of the settlement discussions, however, we inquired whether the U.S. intends to pursue any actions under the False Claims Act. In response, the DOJ sent us a letter stating that the Civil Division of the DOJ, based on facts then known, is no longer pursuing any investigation or claims, and did not have any present intention to pursue any investigation or claims, under the False Claims Act against the various Transocean entities for their involvement in the Macondo well incident. We may request termination of the Consent Decree after we have: (i) completed timely the civil penalty payment requirements of the Consent Decree; (ii) operated under a fully approved Performance Plan required under the Consent Decree for five years; (iii) complied with the terms of the Performance Plan and certain provisions of the Consent Decree, generally relating to a framework and outline of measures to improve performance, for at least 12 consecutive months; and (iv) complied with the other requirements of the Consent Decree, including payment of any stipulated penalties and compliant reporting. We also have agreed that any payments made pursuant to the Plea Agreement or the Consent Decree are not deductible for tax purposes and that we will not use payments pursuant to the Consent Decree as a basis for indemnity or reimbursement from non-insurer defendants named in the complaint by the U.S. On February 5, 2013, the Fifth Circuit Court of Appeals denied our motion to dismiss the appeals by Anadarko, BP and the U.S. regarding the February 22, 2011 ruling of the U.S. District Court, Eastern District of Louisiana. The Fifth Circuit Court of Appeals set a briefing schedule providing for briefing to be completed by May 2013. On February 21, 2013, the U.S. moved to voluntarily dismiss its appeal. Macondo well incident—Federal securities claims—On February 19, 2013, the U.S. District Court, Southern District of New York, granted our motion to stay the federal securities class action against us, former chief executive officers of Transocean Ltd. and one of our acquired subsidiaries before such court pending the decision of the Second Circuit Court of Appeals. Macondo well incident—Insurance coverage—Additionally, subsequent to December 31, 2012, the parties to the second layer interpleader action executed a protocol agreement to facilitate the reimbursement and funding of settlements of personal injury and fatality claims of our crew and vendors using insurance funds. Subsequent to December 31, 2012, our third layer and fourth layer of excess insurers filed an interpleader action. Like the interpleader actions filed by the first layer and the second layer of excess insurers, the third layer and fourth layer of excess insurers contend that they face multiple, and potentially competing, claims to the relevant insurance proceeds. In this action, the insurers effectively ask the court to manage disbursement of the funds to the alleged claimants, as appropriate, and discharge the insurers of any additional liability. The court has not yet issued any rulings on this action. Macondo well incident—Shareholder derivative claims—In connection with two shareholder derivative suits originally filed in June 2010, one of the plaintiffs in January 2013 re-filed a complaint that was previously dismissed seeking to recover damages to the corporation and disgorgement of all profits, benefits, and other compensation from the individual defendants. We intend to file our motion to dismiss in March 2013. Brazil Frade field incident—On February 19, 2013, the federal court in Rio de Janeiro denied the federal police marshal’s recommendation for the criminal indictment of us and five of our employees.

Schedule II - Valuation and Qualifying Accounts

12 Months Ended

Dec. 31, 2012

Schedule II - Valuation and Qualifying Accounts

Schedule II - Valuation and Qualifying Accounts

Transocean Ltd. and Subsidiaries

Schedule II - Valuation and Qualifying Accounts

(In millions)

			Additions
	Balance at beginning of period		Charge to cost and expenses		Charge to other accounts -describe		Deductions -describe			Balance at end of period

Year ended December 31, 2010
Reserves and allowances deducted from asset accounts:
Allowance for doubtful accounts receivable	$	65	$	5	$	—	$	32	(a)	$	38
Allowance for obsolete materials and supplies	66		6		—		2		(b)	70
Valuation allowance on deferred tax assets	160		8		—		4		(c)	164

Year ended December 31, 2011
Reserves and allowances deducted from asset accounts:
Allowance for doubtful accounts receivable	$	38	$	—	$	—	$	10	(a)	$	28
Allowance for obsolete materials and supplies	70		5		—		2		(d)	73
Valuation allowance on deferred tax assets	164		19		—		—			183

Year ended December 31, 2012
Reserves and allowances deducted from asset accounts:
Allowance for doubtful accounts receivable	$	28	$	—	$	—	$	8	(a)	$	20
Allowance for obsolete materials and supplies	73		8		—		15		(d)	66
Valuation allowance on deferred tax assets	183		28		—		1		(c)	210

(a) Uncollectible accounts receivable written off, net of recoveries.

(b) Amount represents $1 million related to sale of rigs and inventory and $1 million related to the loss of Deepwater Horizon.

(d) Amount related to sale of rigs and related equipment.

Other schedules are omitted either because they are not required or are not applicable or because the required information is included in the financial statements or notes thereto.

Significant Accounting Policies (Policies)	12 Months Ended
Significant Accounting Policies (Policies)	Dec. 31, 2012
Significant Accounting Policies
Accounting estimates	Accounting estimates—To prepare financial statements in accordance with accounting principles generally accepted in the U.S., we are required to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosures of contingent assets and liabilities. On an ongoing basis, we evaluate our estimates and assumptions, including those related to our discontinued operations, allowance for doubtful accounts, materials and supplies obsolescence, property and equipment, investments, notes receivable, goodwill and other intangible assets, income taxes, contingencies, share-based compensation, defined benefit pension plans and other postretirement benefits. We base our estimates and assumptions on historical experience and on various other factors we believe are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying amounts of assets and liabilities that are not readily apparent from other sources. Actual results could differ from such estimates.
Fair value measurements	Fair value measurements—We estimate fair value at a price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants in the principal market for the asset or liability. Our valuation techniques require inputs that we categorize using a three-level hierarchy, from highest to lowest level of observable inputs, as follows: (1) significant observable inputs, including unadjusted quoted prices for identical assets or liabilities in active markets (“Level 1”), (2) significant other observable inputs, including direct or indirect market data for similar assets or liabilities in active markets or identical assets or liabilities in less active markets (“Level 2”) and (3) significant unobservable inputs, including those that require considerable judgment for which there is little or no market data (“Level 3”). When multiple input levels are required for a valuation, we categorize the entire fair value measurement according to the lowest level of input that is significant to the measurement even though we may have also utilized significant inputs that are more readily observable.
Consolidation	Consolidation—We consolidate entities in which we have a majority voting interest and entities that meet the criteria for variable interest entities for which we are deemed to be the primary beneficiary for accounting purposes. We eliminate intercompany transactions and accounts in consolidation. We apply the equity method of accounting for an investment in an entity if we have the ability to exercise significant influence over the entity that (a) does not meet the variable interest entity criteria or (b) meets the variable interest entity criteria, but for which we are not deemed to be the primary beneficiary. We apply the cost method of accounting for an investment in an entity if we do not have the ability to exercise significant influence over the unconsolidated entity. See Note 6—Variable Interest Entities. In the year ended December 31, 2012, we did not have interests in any unconsolidated entities for which we earned equity in earnings. In the years ended December 31, 2011 and 2010, we recognized equity in earnings of unconsolidated entities, recorded in other, net, on our consolidated statements of operations, in the amount of $5 million and $8 million, respectively. At December 31, 2012 and 2011, our investments in and advances to unconsolidated affiliates had carrying amounts of less than $1 million.
Business combination	Business combination—In connection with our acquisition of Aker Drilling ASA (“Aker Drilling), we applied the acquisition method of accounting. Accordingly, we recorded the acquired assets and assumed liabilities at fair value and recognized goodwill to the extent the fair value of the business acquired exceeded the fair value of the net assets. We estimated the fair values of the acquired assets and assumed liabilities as of the date of the acquisition. See Note 5—Business Combination.
Discontinued operations	Discontinued operations—We present as discontinued operations the operating results of a component of our business that either has been disposed of or is classified as held for sale when both of the following conditions are met: (a) the operations and cash flows of the component have been or will be eliminated from our ongoing operations as a result of the disposal transaction and (b) we will not have any significant continuing involvement in the operations of the disposed component. For discontinued operations that are disposed of other than by sale, we present the operating results as discontinued in the period in which the disposal group is either abandoned, distributed or exchanged, depending on the manner of disposal. We consider a component of our business to be one that comprises operations and cash flows that can be clearly distinguished, operationally and for financial reporting purposes, from the rest of our business. During the year ended December 31, 2012, we reclassified to discontinued operations the operating results, assets and liabilities associated with the operations of our Standard Jackup and swamp barge asset groups, components of our contract drilling services segment, and the operations of our U.S. Gulf of Mexico drilling management services, a component of our drilling management services segment. During the year ended December 31, 2011, we reclassified to discontinued operations the operating results, assets and liabilities associated with the operations of our Caspian Sea contract drilling operations, a component of our contract drilling services segment, and the operations of our oil and gas properties segment. See Note 9—Discontinued Operations.
Operating revenues and expenses	Operating revenues and expenses—We recognize operating revenues as they are earned, based on contractual dayrates or on a fixed-price basis. In connection with drilling contracts, we may receive revenues for preparation and mobilization of equipment and personnel or for capital improvements to rigs. In connection with new drilling contracts, revenues earned and incremental costs incurred directly related to contract preparation and mobilization are deferred and recognized over the primary contract term of the drilling project using the straight-line method. Our policy to amortize the fees related to contract preparation, mobilization and capital upgrades on a straight-line basis over the estimated firm period of drilling is consistent with the general pace of activity, level of services being provided and dayrates being earned over the life of the contract. For contractual daily rate contracts, we account for loss contracts as the losses are incurred. Costs of relocating drilling units without contracts to more promising market areas are expensed as incurred. Upon completion of drilling contracts, any demobilization fees received are reported in income, as are any related expenses. Capital upgrade revenues received are deferred and recognized over the primary contract term of the drilling project. The actual cost incurred for the capital upgrade is depreciated over the estimated useful life of the asset. We incur periodic survey and drydock costs in connection with obtaining regulatory certification to operate our rigs and well control systems on an ongoing basis. Costs associated with these certifications are deferred and amortized on a straight-line basis over the period until the next survey. Included in our contract drilling revenues, we recognize amortization associated with our drilling contract intangible assets and liabilities. In connection with our business combination with GlobalSantaFe Corporation in November 2007, we recognized drilling contract intangible assets and liabilities for acquired drilling contracts for future contract drilling services. The terms of the acquired contracts include fixed dayrates that were above or below the market dayrates that were available for similar contracts as of the date of the business combination. We recognized the fair value adjustments as contract intangible assets and liabilities, recorded in other assets and other long-term liabilities, respectively. We amortize the resulting contract drilling intangible revenues on a straight-line basis over the respective contract period and include such revenues in contract drilling revenues on our consolidated statements of operations. In the years ended December 31, 2012, 2011 and 2010, we recognized contract drilling intangible revenues of $42 million, $45 million and $98 million, respectively. See Note 13—Goodwill and Other Intangible Assets.
Other revenues	Other revenues—Our other revenues represent those derived from drilling management services and customer reimbursable revenues. For fixed-price contracts associated with our drilling management services, we recognize revenues and expenses upon well completion and customer acceptance, and we recognize loss provisions on contracts in progress when losses are probable. We consider customer reimbursable revenues to be billings to our customers for reimbursement of certain equipment, materials and supplies, third-party services, employee bonuses and other expenses that we recognize in operating and maintenance expense, the result of which has little or no effect on operating income.
Share-based compensation	Share-based compensation—For time-based awards, we recognize compensation expense on a straight-line basis through the date the employee is no longer required to provide service to earn the award (the “service period”). For market-based awards that vest at the end of the service period, we recognize compensation expense on a straight-line basis through the end of the service period. For performance-based awards with graded vesting conditions, we recognize compensation expense on a straight-line basis over the service period for each separately vesting portion of the award as if the award was, in substance, multiple awards. We recognize share-based compensation expense net of a forfeiture rate that we estimate at the time of grant based on historical experience and future expectations, and we adjust the estimated forfeiture rate, if necessary, in subsequent periods based on actual forfeitures or changed expectations. To measure the fair values of time-based restricted shares and deferred units granted or modified, we use the market price of our shares on the grant date or modification date. To measure the fair values of stock options and stock appreciation rights granted or modified, we use the Black-Scholes-Merton option-pricing model and apply assumptions for the expected life, risk-free interest rate, dividend yield and expected volatility. The expected life is based on historical information of past employee behavior regarding exercises and forfeitures of options. The risk-free interest rate is based upon the published U.S. Treasury yield curve in effect at the time of grant or modification for instruments with a similar life. The dividend yield is based on our history and expectation of dividend payouts. The expected volatility is based on a blended rate with an equal weighting of the (a) historical volatility based on historical data for an amount of time approximately equal to the expected life and (b) implied volatility derived from our at-the-money, long-dated call options. To measure the fair values of market-based deferred units granted or modified, we use a Monte Carlo simulation model and, in addition to the assumptions applied for the Black-Scholes-Merton option-pricing model, we apply assumptions using a risk neutral approach and an average price at the performance start date. The risk neutral approach assumes that all peer group stocks grow at the risk-free rate. The average price at the performance start date is based on the average stock price for the preceding 30 trading days. We recognize share-based compensation expense in the same financial statement line item as cash compensation paid to the respective employees. Tax deduction benefits for awards in excess of recognized compensation costs are reported as a financing cash flow. In the years ended December 31, 2012, 2011 and 2010, share-based compensation expense was $97 million, $95 million and $102 million, respectively. In the years ended December 31, 2012, 2011 and 2010, income tax benefit on share-based compensation expense was $12 million, $16 million, and $13 million, respectively. See Note 20—Share-Based Compensation Plans.
Capitalized interest	Capitalized interest—We capitalize interest costs for qualifying construction and upgrade projects. In the years ended December 31, 2012, 2011 and 2010, we capitalized interest costs on construction work in progress of $54 million, $39 million and $89 million, respectively.
Foreign currency	Foreign currency—The majority of our revenues and expenditures are denominated in U.S. dollars to limit our exposure to currency exchange rate fluctuations, resulting in the use of the U.S. dollar as the functional currency for all of our operations. We recognize foreign currency exchange gains and losses in other, net. In the years ended December 31, 2012, 2011 and 2010, we recognized net foreign currency exchange gains (losses) of $(27) million, $(99) million and $1 million, respectively. See Note 15—Derivatives and Hedging.
Income taxes	Income taxes—We provide for income taxes based upon the tax laws and rates in effect in the countries in which operations are conducted and income is earned. There is little or no expected relationship between the provision for or benefit from income taxes and income or loss before income taxes because the countries in which we operate have taxation regimes that vary not only with respect to nominal rate, but also in terms of the availability of deductions, credits and other benefits. Variations also arise because income earned and taxed in any particular country or countries may fluctuate from year to year. We recognize deferred tax assets and liabilities for the anticipated future tax effects of temporary differences between the financial statement basis and the tax basis of our assets and liabilities using the applicable jurisdictional tax rates in effect at year end. We record a valuation allowance for deferred tax assets when it is more likely than not that some or all of the benefit from the deferred tax asset will not be realized. We provide a valuation allowance to offset deferred tax assets for net operating losses incurred during the year in certain jurisdictions and for other deferred tax assets where, in our opinion, it is more likely than not that the financial statement benefit of these losses will not be realized. We provide a valuation allowance for foreign tax credit carryforwards to reflect the possible expiration of these benefits prior to their utilization. We maintain liabilities for estimated tax exposures in our jurisdictions of operation, and the provisions and benefits resulting from changes to those liabilities are included in our annual tax provision along with related interest and penalties. Tax exposure items include potential challenges to permanent establishment positions, intercompany pricing, disposition transactions, and withholding tax rates and their applicability. These exposures are resolved primarily through the settlement of audits within these tax jurisdictions or by judicial means, but can also be affected by changes in applicable tax law or other factors, which could cause us to revise past estimates. See Note 8—Income Taxes.
Cash and cash equivalents	Cash and cash equivalents—Cash equivalents are highly liquid debt instruments with original maturities of three months or less that may include time deposits with commercial banks that have high credit ratings, U.S. Treasury and government securities, Eurodollar time deposits, certificates of deposit and commercial paper. We may also invest excess funds in no-load, open-end, management investment trusts (“management trusts”). The management trusts invest exclusively in high-quality money market instruments. We maintain restricted cash investments that are pledged for debt service, as required under certain bank credit agreements. We classify such restricted cash investment balances in other current assets if the restriction is expected to expire within one year and in other assets if the restriction is expected to expire in greater than one year. At December 31, 2012, the aggregate carrying amount of our restricted cash investments was $857 million, of which $195 million and $662 million was classified in other current assets and other assets, respectively. At December 31, 2011, the aggregate carrying amount of our restricted cash investments was $934 million, of which $182 million and $752 million was classified in other current assets and other assets, respectively. See Note 14—Debt.
Accounts receivable	Accounts receivable—We derive a majority of our revenues from services to international oil companies and government-owned or government-controlled oil companies. We evaluate the credit quality of our customers on an ongoing basis, and we do not generally require collateral or other security to support customer receivables. We establish an allowance for doubtful accounts on a case-by-case basis, considering changes in the financial position of a major customer, when we believe the required payment of specific amounts owed to us is unlikely to occur. At December 31, 2012 and 2011, the allowance for doubtful accounts was $20 million and $28 million, respectively.
Materials and supplies	Materials and supplies—We record materials and supplies at their average cost less an allowance for obsolescence. We estimate the allowance for obsolescence based on historical experience and expectations for future use of the materials and supplies. At December 31, 2012 and 2011, the allowance for obsolescence was $66 million and $73 million, respectively.
Assets held for sale	Assets held for sale—We classify an asset as held for sale when the facts and circumstances meet the criteria for such classification, including the following: (a) we have committed to a plan to sell the asset, (b) the asset is available for immediate sale, (c) we have initiated actions to complete the sale, including locating a buyer, (d) the sale is expected to be completed within one year, (e) the asset is being actively marketed at a price that is reasonable relative to its fair value, and (f) the plan to sell is unlikely to be subject to significant changes or termination. At December 31, 2012 and 2011, assets held for sale were $179 million and $26 million, respectively. See Note 9—Discontinued Operations.
Property and equipment	Property and equipment—The carrying amounts of our property and equipment, consisting primarily of offshore drilling rigs and related equipment, are based on our estimates, assumptions and judgments relative to capitalized costs, useful lives and salvage values of our rigs. These estimates, assumptions and judgments reflect both historical experience and expectations regarding future industry conditions and operations. At December 31, 2012, the aggregate carrying amount of our property and equipment represented approximately 61 percent of our total assets. We compute depreciation using the straight-line method after allowing for salvage values. We capitalize expenditures for renewals, replacements and improvements, and we expense maintenance and repair costs as incurred. Upon sale or other disposition of an asset, we recognize a net gain or loss on disposal of the asset, which is measured as the difference between the net carrying amount of the asset and the net proceeds received. Estimated original useful lives of our drilling units range from 18 to 35 years, our buildings and improvements range from 10 to 30 years and our machinery and equipment range from four to 12 years. From time to time, we may review the estimated remaining useful lives of our drilling units, and we may extend the useful life when events and circumstances indicate a drilling unit can operate beyond its remaining useful life. During the year ended December 31, 2012, we adjusted the useful lives for three rigs, extending the estimated useful lives from between 29 and 30 years to between 35 and 38 years. During the year ended December 31, 2011, we adjusted the useful lives for two rigs, extending the estimated useful lives from between 20 and 30 years to between 23 and 38 years. During the year ended December 31, 2010, we adjusted the useful lives for five rigs, extending the estimated useful lives from between 20 and 36 years to between 25 and 39 years. We deemed the life extensions appropriate for each of these rigs based on the respective contracts under which the rigs were operating and the additional life-extending work, upgrades and inspections we performed on the rigs. In each of the years ended December 31, 2012, 2011 and 2010, the changes in estimated useful lives of these rigs resulted in a reduction in annual depreciation expense of $27 million ($0.08 per diluted share from continuing operations), $2 million ($0.01 per diluted share from continuing operations) and $23 million ($0.07 per diluted share from continuing operations), respectively, which had no tax effect for any period.
Long-lived assets and definite-lived intangible assets	Long-lived assets and definite-lived intangible assets—We review the carrying amounts of long-lived assets and definite-lived intangible assets, principally property and equipment for potential impairment when events occur or circumstances change that indicate that the carrying value of such assets may not be recoverable. For assets classified as held and used, we determine recoverability by evaluating the undiscounted estimated future net cash flows, based on projected dayrates and utilization, of the asset group under review. We consider our asset groups to be Ultra-Deepwater Floaters, Deepwater Floaters, Harsh Environment Floaters, Midwater Floaters and High-Specification Jackups. When an impairment of one or more of our asset groups is indicated, we measure the impairment as the amount by which the asset group’s carrying amount exceeds its estimated fair value. We measure the fair values of our contract drilling asset groups by applying a combination of income and market approaches, using projected discounted cash flows and estimates of the exchange price that would be received for the assets in the principal or most advantageous market for the assets in an orderly transaction between market participants as of the measurement date. For our drilling management services customer relationships asset, we estimate fair value using the excess earnings method, which applies the income approach. For an asset classified as held for sale, we consider the asset to be impaired to the extent its carrying amount exceeds its estimated fair value less cost to sell. In the year ended December 31, 2012, we determined that the customer relationships intangible asset associated with our drilling management services reporting unit was impaired, and we recognized a loss on impairment of $22 million ($17 million, or $0.05 per diluted share, net of tax).
Goodwill and other indefinite-lived intangible assets	Goodwill and other indefinite-lived intangible assets—We conduct impairment testing for our goodwill and other indefinite-lived intangible assets annually as of October 1 and more frequently, on an interim basis, when an event occurs or circumstances change that may indicate a reduction in the fair value of a reporting unit or the indefinite-lived intangible asset is below its carrying value. We test goodwill at the reporting unit level, which is defined as an operating segment or one level below an operating segment that constitutes a business for which financial information is available and is regularly reviewed by management. We have identified two reporting units for this purpose: (1) contract drilling services and (2) drilling management services. Before testing goodwill, we consider whether or not to first assess qualitative factors to determine whether the existence of events or circumstances lead to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount and whether the two-step impairment test is required. If, as the result of our qualitative assessment, we determine that the two-step impairment test is required, or, alternatively, if we elect to forgo the qualitative assessment, we test goodwill for impairment by comparing the carrying amount of the reporting unit, including goodwill, to the fair value of the reporting unit. For our contract drilling services reporting unit, we estimate fair value using projected discounted cash flows, publicly traded company multiples and acquisition multiples. To develop the projected cash flows associated with our contract drilling services reporting unit, which are based on estimated future dayrates and utilization, we consider key factors that include assumptions regarding future commodity prices, credit market conditions and the effect these factors may have on our contract drilling operations and the capital expenditure budgets of our customers. We discount the projected cash flows using a long-term, risk-adjusted weighted-average cost of capital, which is based on our estimate of the investment returns that market participants would require for each of our reporting units. We derive publicly traded company multiples for companies with operations similar to our reporting units using observable information related to shares traded on stock exchanges and, when available, observable information related to recent acquisitions. If the reporting unit’s carrying amount exceeds its fair value, we consider goodwill impaired and perform a second step to measure the amount of the impairment loss, if any. As a result of our annual impairment test, performed as of October 1, 2011, we determined that the goodwill associated with our contract drilling services reporting unit was impaired due to a decline in projected cash flows and market valuations for this reporting unit. In the year ended December 31, 2011, we recognized a loss on impairment, representing our best estimate, in the amount of $5.2 billion ($16.15 per diluted share from continuing operations), which had no tax effect. In the three months ended March 31, 2012, we completed our analysis and recognized an incremental adjustment to our original estimate in the amount of $118 million ($0.33 per diluted share from continuing operations), which had no tax effect. As a result of our annual goodwill impairment test in the years ended December 31, 2012 and 2010, we concluded that goodwill was not impaired. See Note 7—Intangible Asset Impairments and Note 13—Goodwill and Other Intangible Assets.
Derivatives and hedging	Derivatives and hedging—From time to time, we may enter into a variety of derivative financial instruments in connection with the management of our exposure to variability in interest rates and currency exchange rates. We record derivatives on our consolidated balance sheet, measured at fair value. For derivatives that do not qualify for hedge accounting, we recognize the gains and losses associated with changes in the fair value in current period earnings. We may enter into cash flow hedges to manage our exposure to variability of the expected future cash flows of recognized assets or liabilities or of unrecognized forecasted transactions. For a derivative that is designated and qualifies as a cash flow hedge, we initially recognize the effective portion of the gains or losses in other comprehensive income and subsequently recognize the gains and losses in earnings in the period in which the hedged forecasted transaction affects earnings. We recognize the gains and losses associated with the ineffective portion of the hedges in interest expense in the period in which they are realized. We may enter into fair value hedges to manage our exposure to changes in fair value of recognized assets or liabilities, such as fixed-rate debt, or of unrecognized firm commitments. For a derivative that is designated and qualifies as a fair value hedge, we simultaneously recognize in current period earnings the gains or losses on the derivative along with the offsetting losses or gains on the hedged item attributable to the hedged risk. The resulting ineffective portion, which is measured as the difference between the change in fair value of the derivative and the hedged item, is recognized in current period earnings. See Note 15—Derivatives and Hedging, Note 23—Financial Instruments and Note 24—Risk Concentration.
Pension and other postretirement benefits	Pension and other postretirement benefits—We use a measurement date of January 1 for determining net periodic benefit costs and December 31 for determining benefit obligations and the fair value of plan assets. We determine our net periodic benefit costs based on a market-related value of assets that reduces year-to-year volatility by including investment gains or losses subject to amortization over a five-year period from the year in which they occur. Investment gains or losses for this purpose are measured as the difference between the expected return calculated using the market-related value of assets and the actual return based on the market-related value of assets. If gains or losses exceed 10 percent of the greater of plan assets or plan liabilities, we amortize such gains or losses over the average expected future service period of the employee participants. We measure our actuarially determined obligations and related costs for our defined benefit pension and other postretirement benefit plans, retiree life insurance and medical benefits, by applying assumptions, including long-term rate of return on plan assets, discount rates, compensation increases, employee turnover rates and health care cost trend rates. The two most critical assumptions are the long-term rate of return on plan assets and the discount rate. For the long-term rate of return, we develop our assumptions regarding the expected rate of return on plan assets based on historical experience and projected long-term investment returns, which are weighted to consider each plan’s target asset allocation. For the discount rate, we base our assumptions on a yield curve approach using Aa-rated corporate bonds and the expected timing of future benefit payments. For the projected compensation trend rate, we consider short-term and long-term compensation expectations for participants, including salary increases and performance bonus payments. For the health care cost trend rate for other postretirement benefits, we establish our assumptions for health care cost trends, applying an initial trend rate that reflects both our recent historical experience and broader national statistics with an ultimate trend rate that assumes that the portion of gross domestic product devoted to health care eventually becomes constant. At December 31, 2012 and 2011, pension and other postretirement benefit plan obligations represented an aggregate liability in the amount of their net underfunded status of $639 million and $640 million, respectively. In the years ended December 31, 2012, 2011 and 2010, net periodic benefit costs were $149 million, $88 million and $91 million, respectively. See Note 16—Postemployment Benefit Plans.
Contingencies	Contingencies—We perform assessments of our contingencies on an ongoing basis to evaluate the appropriateness of our liabilities and disclosures for such contingencies. We establish liabilities for estimated loss contingencies when we believe a loss is probable and the amount of the probable loss can be reasonably estimated. We recognize corresponding assets for those loss contingencies that we believe are probable of being recovered through insurance. Once established, we adjust the carrying amount of a contingent liability upon the occurrence of a recognizable event when facts and circumstances change, altering our previous assumptions with respect to the likelihood or amount of loss. We recognize liabilities for legal costs as they are incurred, and we recognize a corresponding asset for those legal costs only if we expect such legal costs to be recovered through insurance.
Reclassifications	Reclassifications—We have made certain reclassifications, which did not have an effect on net income, to prior period amounts to conform with the current year’s presentation, including certain reclassifications to our consolidated statements of financial position, results of operations and cash flows to present our Standard Jackup and swamp barge disposal groups and our U.S. Gulf of Mexico drilling management services operations as discontinued operations (see Note 9—Discontinued Operations). Other reclassifications did not have a material effect on our consolidated statement of financial position, results of operations or cash flows.
Subsequent events	Subsequent events—We evaluate subsequent events through the time of our filing on the date we issue our financial statements. See Note 29—Subsequent Events.

Correction of Errors in Previously Reported Consolidated Financial Statements (Tables)

12 Months Ended

Dec. 31, 2012

Correction of Errors in Previously Reported Consolidated Financial Statements

Summary of correction of previously reported financial statements

	Years ended December 31,
	2011			2010
Legal and other costs	$	(67	)	$	—
Repair and maintenance costs	11			(11		)
Income tax (expense) benefit	16			(4		)
Other immaterial adjustments, net	9			(4		)
Net adjustment to income from continuing operations	(31		)	(19		)
Net adjustment to income from discontinued operations, net of tax	(14		)	—
Net adjustment to net income attributable to noncontrolling interest	16			(16		)
Net adjustment to net income attributable to controlling interest	$	(29	)	$	(35	)

	Year ended December 31, 2011									Year ended December 31, 2010
	Previously reported			Adjustments			As adjusted			Previously reported			Adjustments			As adjusted
Operating revenues
Contract drilling revenues	$	7,413		$	(6	)	$	7,407		$	7,698		$	—		$	7,698
Other revenues	620			—			620			251			—			251
	8,033			(6		)	8,027			7,949			—			7,949
Costs and expenses
Operating and maintenance	6,134			45			6,179			4,204			15			4,219
Depreciation and amortization	1,113			(4		)	1,109			1,009			—			1,009
General and administrative	288			—			288			246			—			246
	7,535			41			7,576			5,459			15			5,474
Loss on impairment	(5,201		)	—			(5,201		)	—			—			—
Gain (loss) on disposal of assets, net	(12		)	—			(12		)	255			—			255
Operating income (loss)	(4,715		)	(47		)	(4,762		)	2,745			(15		)	2,730

Other income (expense), net
Interest income	44			—			44			23			—			23
Interest expense, net of amounts capitalized	(621		)	—			(621		)	(567		)	—			(567		)
Other, net	(99		)	—			(99		)	(31		)	—			(31		)
	(676		)	—			(676		)	(575		)	—			(575		)
Income (loss) from continuing operations before income tax expense	(5,391		)	(47		)	(5,438		)	2,170			(15		)	2,155
Income tax (benefit) expense	340			(16		)	324			288			4			292
Income (loss) from continuing operations	(5,731		)	(31		)	(5,762		)	1,882			(19		)	1,863
Income (loss) from discontinued operations, net of tax	99			(14		)	85			(894		)	—			(894		)

Net income (loss)	(5,632		)	(45		)	(5,677		)	988			(19		)	969
Net income (loss) attributable to noncontrolling interest	93			(16		)	77			27			16			43
Net income (loss) attributable to controlling interest	$	(5,725	)	$	(29	)	$	(5,754	)	$	961		$	(35	)	$	926

Earnings (loss) per share-basic
Earnings (loss) from continuing operations	$	(18.10	)	$	(0.04	)	$	(18.14	)	$	5.77		$	(0.11	)	$	5.66
Earnings (loss) from discontinued operations	0.31			(0.05		)	0.26			(2.78		)	—			(2.78		)
Earnings (loss) per share	$	(17.79	)	$	(0.09	)	$	(17.88	)	$	2.99		$	(0.11	)	$	2.88

Earnings (loss) per share-diluted
Earnings (loss) from continuing operations	$	(18.10	)	$	(0.04	)	$	(18.14	)	$	5.77		$	(0.11	)	$	5.66
Earnings (loss) from discontinued operations	0.31			(0.05		)	0.26			(2.78		)	—			(2.78		)
Earnings (loss) per share	$	(17.79	)	$	(0.09	)	$	(17.88	)	$	2.99		$	(0.11	)	$	2.88

	December 31, 2011									December 31, 2010
	Previously reported			Adjustments			As adjusted			Previously reported			Adjustments			As adjusted
Assets
Cash and cash equivalents	$	4,017		$	—		$	4,017		$	3,394		$	(40	)	$	3,354
Accounts receivable, net
Trade	2,049			—			2,049			1,653			—			1,653
Other	127			—			127			190			—			190
Materials and supplies, net	529			—			529			425			—			425
Deferred income taxes, net	142			—			142			115			—			115
Assets held for sale	26			—			26			—			—			—
Other current assets	719			(73		)	646			418			54			472
Total current assets	7,609			(73		)	7,536			6,195			14			6,209

Property and equipment	24,833			—			24,833			22,149			—			22,149
Property and equipment of consolidated variable interest entities	2,252			—			2,252			2,214			—			2,214
Less accumulated depreciation	6,301			(4		)	6,297			5,244			—			5,244
Property and equipment, net	20,784			4			20,788			19,119			—			19,119
Goodwill	3,205			12			3,217			8,132			—			8,132
Other assets	3,490			1			3,491			3,365			(11		)	3,354
Total assets	$	35,088		$	(56	)	$	35,032		$	36,811		$	3		$	36,814

Liabilities and equity
Accounts payable	$	880		$	—		$	880		$	832		$	—		$	832
Accrued income taxes	86			—			86			109			—			109
Debt due within one year	1,942			—			1,942			1,917			—			1,917
Debt of consolidated variable interest entities due within one year	97			148			245			95			148			243
Other current liabilities	2,353			22			2,375			883			12			895
Total current liabilities	5,358			170			5,528			3,836			160			3,996

Long-term debt	10,756			—			10,756			8,354			—			8,354
Long-term debt of consolidated variable interest entities	741			(148		)	593			855			(148		)	707
Deferred income taxes, net	491			(4		)	487			575			10			585
Other long-term liabilities	1,935			(10		)	1,925			1,791			—			1,791
Total long-term liabilities	13,923			(162		)	13,761			11,575			(138		)	11,437

Commitments and contingencies
Redeemable noncontrolling interest	116			—			116			25			16			41

Shares	4,982			—			4,982			4,482			—			4,482
Additional paid-in capital	7,211			—			7,211			7,504			—			7,504
Treasury shares, at cost	(240		)	—			(240		)	(240		)	—			(240		)
Retained earnings	4,244			(64		)	4,180			9,969			(35		)	9,934
Accumulated other comprehensive loss	(496		)	—			(496		)	(332		)	—			(332		)
Total controlling interest shareholders’ equity	15,701			(64		)	15,637			21,383			(35		)	21,348
Noncontrolling interest	(10		)	—			(10		)	(8		)	—			(8		)
Total equity	15,691			(64		)	15,627			21,375			(35		)	21,340
Total liabilities and equity	$	35,088		$	(56	)	$	35,032		$	36,811		$	3		$	36,814

- Definition

Tabular disclosure of prior period adjustments to previously issued financial statements including (1) the effect of the correction on each financial statement line item and any per-share amounts affected for each prior period presented (2) the cumulative effect of the change on retained earnings or other appropriate components of equity or net assets in the statement of financial position, as of the beginning of the earliest period presented, and (3) the effect of the prior period adjustments (both gross and net of applicable income tax) on the net income of each prior period presented in the entity's annual report for the year in which the adjustments are made.

+ References+ Details

Business Combination (Tables)

12 Months Ended

Dec. 31, 2012

Business Combination

Schedule of pro forma combined operating results from continuing operations

Unaudited pro forma combined operating results, assuming the acquisition was completed as of January 1, 2010, were as follows (in millions, except per share data):

	Years ended December 31,
	2011			2010
Operating revenues	$	8,339		$	8,280
Operating income (loss)	(4,616		)	2,848
Income (loss) from continuing operations	(5,664		)	1,899

Per share earnings (loss) from continuing operations
Basic	$	(17.84	)	$	5.77
Diluted	$	(17.84	)	$	5.77

- Definition

Tabular disclosure of pro forma results of operations for a material business acquisition or series of individually immaterial business acquisitions that are material in the aggregate.

+ References+ Details

Variable Interest Entities (Tables)

12 Months Ended

Dec. 31, 2012

Variable Interest Entities

Carrying Amounts of Variable Interest Entities

The carrying amounts associated with our consolidated variable interest entities, after eliminating the effect of intercompany transactions, were as follows (in millions):

	December 31, 2012						December 31, 2011
	Assets		Liabilities		Net carrying amount		Assets		Liabilities		Net carrying amount
Variable interest entity
TPDI	$	—	$	—	$	—	$	1,562	$	673	$	889
ADDCL	954		296		658		930		334		596
TDSOI	277		15		262		—		—		—
Total	$	1,231	$	311	$	920	$	2,492	$	1,007	$	1,485

- Definition

Tabular disclosure of the significant judgments and assumptions made in determining whether a variable interest (as defined) held by the entity requires the variable interest entity (VIE) (as defined) to be consolidated and (or) disclose information about its involvement with the VIE, individually or in aggregate (as applicable); the nature of restrictions, if any, on the consolidated VIE's assets and on the settlement of its liabilities reported by an entity in its statement of financial position, including the carrying amounts of such assets and liabilities; the nature of, and changes in, the risks associated with involvement in the VIE; how involvement with the VIE affects the entity's financial position, financial performance, and cash flows; the lack of recourse if creditors (or beneficial interest holders) of the consolidated VIE have no recourse to the general credit of the primary beneficiary (if applicable); the terms of arrangements, giving consideration to both explicit arrangements and implicit variable interests, if any, that could require the entity to provide financial support to the VIE, including events or circumstances that could expose the entity to a loss; the methodology used by the entity for determining whether or not it is the primary beneficiary of the variable interest entity; the significant factors considered and judgments made in determining that the power to direct the activities of a VIE that most significantly impact the VIE's economic performance are shared (as defined); the carrying amounts and classification of assets and liabilities of the VIE included in the statement of financial position; the entity's maximum exposure to loss, if any, as a result of its involvement with the VIE, including how the maximum exposure is determined and significant sources of the entity's exposure to the VIE; a comparison of the carrying amounts of the assets and liabilities and the entity's maximum exposure to loss; information about any liquidity arrangements, guarantees, and (or) other commitments by third parties that may affect the fair value or risk of the entity's variable interest in the VIE; whether or not the entity has provided financial support or other support (explicitly or implicitly) to the VIE that it was not previously contractually required to provide or whether the entity intends to provide that support, including the type and amount of the support and the primary reasons for providing the support; and supplemental information the entity determines necessary to provide.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 167

-Paragraph 22E

-Appendix D

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Interpretation (FIN)

-Number 46R

-Paragraph 4

-Subparagraph g

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 167

-Paragraph 22B

-Appendix D

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 167

-Paragraph 23A

-Appendix D

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 3

-URI http://asc.fasb.org/extlink&oid=7880789&loc=d3e5710-111685

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 5A

-URI http://asc.fasb.org/extlink&oid=7880789&loc=SL6759159-111685

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 6

-URI http://asc.fasb.org/extlink&oid=7880789&loc=d3e5747-111685

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=7880789&loc=d3e5728-111685

Reference 9: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 9

-URI http://asc.fasb.org/extlink&oid=7880789&loc=SL6228884-111685

Reference 10: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Variable Interest Entity

-URI http://asc.fasb.org/extlink&oid=6528138

Reference 11: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 140

-Paragraph 35

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 12: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Interpretation (FIN)

-Number 46R

-Paragraph 2, 14, 15, 16, 23, 24, 25, 26

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 13: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 167

-Paragraph 24

-Appendix D

Reference 14: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS140-4/FIN46(R)-8

-Paragraph C4

-Subparagraph d

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2012

Income Taxes

Components of the provision (benefit) for income taxes

The components of our provision (benefit) for income taxes were as follows (in millions):

	Years ended December 31,
	2012			2011			2010
Current tax expense	$	183		$	386		$	396
Deferred tax benefit	(133		)	(62		)	(104		)
Income tax expense	$	50		$	324		$	292

Reconciliation of the differences between income tax expense computed at the Swiss holding company statutory rate and the reported provision for income taxes

	Years ended December 31,
	2012			2011			2010
Income tax expense at the Swiss federal statutory rate	$	68		$	(426	)	$	168
Taxes on earnings subject to rates different than the Swiss federal statutory rate	141			221			72
Taxes on impairment loss subject to rates different than the Swiss federal statutory rate	5			409			—
Taxes on asset sales subject to rates different than the Swiss federal statutory rate	(1		)	—			—
Taxes on litigation matters subject to rates different than the Swiss federal statutory rate	59			78			—
Changes in unrecognized tax benefits, net	(179		)	40			73
Change in valuation allowance	1			19			4
Benefit from foreign tax credits	(38		)	(28		)	(23		)
Taxes on asset acquisition costs at rates lower than the Swiss federal statutory rate	—			8			—
Other, net	(6		)	3			(2		)
Income tax expense	$	50		$	324		$	292

Significant components of deferred tax assets and liabilities

The significant components of our deferred tax assets and liabilities were as follows (in millions):

	December 31,
	2012			2011
Deferred tax assets
Drilling contract intangibles	$	1		$	2
Net operating loss carryforwards	380			331
Tax credit carryforwards	41			45
Accrued payroll expenses not currently deductible	95			79
Deferred income	86			65
Valuation allowance	(210		)	(183		)
Other	108			104
Total deferred tax assets	501			443

Deferred tax liabilities
Depreciation and amortization	(688		)	(746		)
Drilling management services intangibles	—			—
Other	(37		)	(42		)
Total deferred tax liabilities	(725		)	(788		)

Net deferred tax liabilities	$	(224	)	$	(345	)

Valuation allowance for non-current deferred tax assets

The valuation allowance for our non-current deferred tax assets was as follows (in millions):

	December 31,
	2012		2011
Valuation allowance for non-current deferred tax assets	$	210	$	183

Reconciliation of unrecognized tax benefits, excluding interest and penalties

The changes to our liabilities related to unrecognized tax benefits, excluding interest and penalties that we recognize as a component of income tax expense, were as follows (in millions):

	Years ended December 31,
	2012			2011			2010
Balance, beginning of period	$	515		$	485		$	460
Additions for current year tax positions	58			45			46
Additions for prior year tax positions	25			29			9
Reductions for prior year tax positions	(24		)	—			(11		)
Settlements	(120		)	(42		)	(17		)
Reductions related to statute of limitation expirations	(72		)	(2		)	(2		)
Balance, end of period	$	382		$	515		$	485

Schedule of unrecognized tax benefits, including related interest and penalties

The liabilities related to our unrecognized tax benefits, including related interest and penalties that we recognize as a component of income tax expense, were as follows (in millions):

	December 31,
	2012		2011
Unrecognized tax benefits, excluding interest and penalties	$	382	$	515
Interest and penalties	199		256
Unrecognized tax benefits, including interest and penalties	$	581	$	771

- Definition

Tabular disclosure of tax positions taken in the tax returns filed or to be filed for which it is more likely than not that the tax position will not be sustained upon examination by taxing authorities (i.e., uncertain tax positions) and other types of income tax contingencies, including: (1) the policy on classification of interest and penalties; (2) a tabular reconciliation of the total amounts of unrecognized tax benefits at the beginning and end of the period; the total amount(s) of: (3) unrecognized tax benefits that, if recognized, would affect the effective tax rate, and (4) interest and penalties recognized in each of the income statement and balance sheet; (5) for positions for which it is reasonably possible that the total amounts unrecognized will significantly change within 12 months of the reporting date the: (i) nature of the uncertainty, (ii) nature of the event that could occur that would cause the change, and (iii) an estimate of the range of the reasonably possible change or a statement that an estimate of the range cannot be made; and (6) a description of tax years that remain subject to examination by major tax jurisdictions.

+ References+ Details

- Definition

Tabular disclosure of valuation allowances to reduce deferred tax assets to net realizable value, including identification of the deferred tax asset more likely than not will not be fully realized and the corresponding amount of the valuation allowance.

+ References+ Details

Discontinued Operations (Tables)

12 Months Ended

Dec. 31, 2012

Discontinued Operations

Summarized results income statement, assets and liabilities of discontinued operations

The summarized results of operations included in income from discontinued operations were as follows (in millions):

	Years ended December 31,
	2012			2011			2010
Operating revenues	$	1,055		$	1,171		$	1,627
Operating and maintenance expense	(990		)	(871		)	(916		)
Depreciation and amortization expense	(183		)	(342		)	(580		)
Loss on impairment of assets in discontinued operations, net	(986		)	(38		)	(1,012		)
Gain on disposal of discontinued operations, net	82			183			2
Other income, net	—			18			8
Income (loss) from discontinued operations before income tax expense	(1,022		)	121			(871		)
Income tax expense	(5		)	(36		)	(23		)
Income (loss) from discontinued operations, net of tax	$	(1,027	)	$	85		$	(894	)

The carrying amounts of the major classes of assets and liabilities associated with our discontinued operations were classified as follows (in millions):

	December 31,
	2012		2011
Assets
Rigs and related equipment, net	$	104	$	—
Materials and supplies	71		—
Oil and gas properties, net	—		24
Other related assets	4		2
Assets held for sale	$	179	$	26

Materials and supplies	$	—	$	98
Other assets	—		21
Other current assets	$	—	$	119

Rig and related equipment, net	$	—	$	1,745
Intangible assets	—		70
Deferred costs	—		42
Other assets	$	—	$	1,857

Liabilities
Deferred revenues	$	32	$	17
Deferred income taxes, net	—		6
Other liabilities	3		14
Other current liabilities	$	35	$	37

Deferred revenues	$	—	$	8
Deferred taxes, net	—		32
Other long-term liabilities	$	—	$	40

- Definition

Tabular disclosure of disposal groups, which may include the gain (loss) recognized in the income statement and the income statement caption that includes that gain (loss), amounts of revenues and pretax profit or loss reported in discontinued operations, the classification and carrying value of the assets and liabilities comprising the disposal group, and the segment in which the disposal group was reported. Also may include the amount of adjustments to amounts previously reported in discontinued operations such as resolution of contingencies arising from the disposal transaction or the operations of the component prior to disposal.

+ References+ Details

Earnings (Loss) Per Share (Tables)

12 Months Ended

Dec. 31, 2012

Earnings (Loss) Per Share

Earnings (Loss) Per Share

The numerator and denominator used for the computation of basic and diluted per share earnings from continuing operations were as follows (in millions, except per share data):

	Years ended December 31,
	2012				2011						2010
	Basic		Diluted		Basic			Diluted			Basic			Diluted
Numerator for earnings (loss) per share
Income (loss) from continuing operations attributable to controlling interest	$	808	$	808	$	(5,839	)	$	(5,839	)	$	1,820		$	1,820
Undistributed earnings allocable to participating securities	—		—		—			—			(10		)	(10		)
Income (loss) from continuing operations available to shareholders	$	808	$	808	$	(5,839	)	$	(5,839	)	$	1,810		$	1,810

Denominator for earnings (loss) per share
Weighted-average shares outstanding	356		356		322			322			320			320
Effect of stock options and other share-based awards	—		—		—			—			—			—
Weighted-average shares for per share calculation	356		356		322			322			320			320

Per share earnings (loss) from continuing operations	$	2.27	$	2.27	$	(18.14	)	$	(18.14	)	$	5.66		$	5.66

Other Comprehensive Income (Loss) (Tables)

12 Months Ended

Dec. 31, 2012

Other Comprehensive Income (Loss)

Schedule of allocation of other comprehensive income (loss) attributable to controlling interest and to noncontrolling interest

The allocation of other comprehensive income (loss) attributable to controlling interest and to noncontrolling interest was as follows (in millions):

	Years ended December 31,
	2012									2011									2010
	Controlling interest			Non- controlling interest (a)			Total			Controlling interest			Non- controlling interest (a)			Total			Controlling interest			Non- controlling interest (a)			Total
Unrecognized components of net periodic benefit costs	$	(52	)	$	—		$	(52	)	$	(204	)	$	—		$	(204	)	$	(8	)	$	—		$	(8	)
Unrecognized gain (loss) on derivative instruments	6			(3		)	3			3			(16		)	(13		)	(10		)	(19		)	(29		)
Unrecognized loss on marketable securities	—			—			—			(13		)	—			(13		)	—			—			—
Recognized components of net periodic benefit costs	47			—			47			25			—			25			16			—			16
Recognized (gain) loss on derivative instruments	(4		)	3			(1		)	(1		)	12			11			14			(2		)	12
Recognized loss on marketable securities	2			—			2			13			—			13			—			—			—

Other comprehensive income (loss) before income taxes	(1		)	—			(1		)	(177		)	(4		)	(181		)	12			(21		)	(9		)
Income taxes related to other comprehensive income (loss)	(7		)	—			(7		)	13			—			13			(9		)	—			(9		)
Other comprehensive income (loss), net of tax	$	(8	)	$	—		$	(8	)	$	(164	)	$	(4	)	$	(168	)	$	3		$	(21	)	$	(18	)

(a) Includes amounts attributable to noncontrolling interest and redeemable noncontrolling interest.

- Definition

Tabular disclosure of components of comprehensive income (loss) including, but not limited to: (a) foreign currency translation adjustments; (b) gains (losses) on foreign currency transactions that are designated as, and are effective as, economic hedges of a net investment in a foreign entity; (c) gains (losses) on intercompany foreign currency transactions that are of a long-term-investment nature, when the entities to the transaction are consolidated, combined, or accounted for by the equity method in the reporting enterprise's financial statements; (d) change in the market value of a futures contract that qualifies as a hedge of an asset reported at fair value; (e) unrealized holding gains (losses) on available-for-sale securities and that resulting from transfers of debt securities from the held-to-maturity category to the available-for-sale category; (f) a net loss recognized as an additional pension liability not yet recognized as net periodic pension cost; and (g) the net gain (loss) and net prior service cost or credit for pension plans and other postretirement benefit plans.

+ References+ Details

Drilling Fleet (Tables)

12 Months Ended

Dec. 31, 2012

Drilling Fleet

Actual capital expenditures and other capital additions, including capitalized interest

Capital expenditures and other capital additions, including capitalized interest, for each of the three years ended December 31, 2012 were as follows (in millions):

	Years ended December 31,
	2012			2011			2010
Construction work in progress, at beginning of period	$	1,360		$	1,450		$	3,657

Newbuild construction program
Ultra-Deepwater Floater TBN1 (a)	139			—			—
Ultra-Deepwater Floater TBN2 (a)	128			—			—
Ultra-Deepwater Floater TBN3 (a)	76			—			—
Ultra-Deepwater Floater TBN4 (a)	76			—			—
Transocean Ao Thai (b)	72			80			—
Deepwater Asgard (c)	46			4			—
Deepwater Invictus (c)	40			3			—
Transocean Siam Driller (b)	39			113			9
Transocean Andaman (b)	38			113			9
Transocean Honor (d)	35			129			98
Deepwater Champion (e)	—			76			249
Discoverer India (f)	—			—			262
Discoverer Luanda (g)	—			—			212
Dhirubhai Deepwater KG2 (h)	—			—			45
Discoverer Inspiration (h)	—			—			33
Other construction projects and capital additions	614			456			432
Total capital expenditures	1,303			974			1,349
Acquisition of construction work in progress (c)	—			272			—
Changes in accrued capital expenditures	61			(2		)	(57		)

Property and equipment placed into service
Transocean Honor (d)	(262		)	—			—
Deepwater Champion (e)	—			(881		)	—
Discoverer India (f)	—			—			(835		)
Discoverer Luanda (g)	—			—			(783		)
Discoverer Inspiration (h)	—			—			(781		)
Dhirubhai Deepwater KG2 (h)	—			—			(707		)
Other property and equipment	(490		)	(453		)	(393		)
Construction work in progress, at end of period	$	1,972		$	1,360		$	1,450

(e) Deepwater Champion, an Ultra-Deepwater drillship, commenced operations in May 2011.

(f) Discoverer India, an Ultra-Deepwater drillship, commenced operations in December 2010.

(h) Discoverer Inspiration and Dhirubhai Deepwater KG2, two Ultra-Deepwater drillships, commenced operations in March 2010.

Goodwill and Other Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2012

Goodwill and Other Intangible Assets

Schedule of gross carrying amounts of goodwill and accumulated impairment

The gross carrying amounts of goodwill and accumulated impairment associated with our contract drilling services were as follows (in millions):

	Year ended December 31, 2012									Year ended December 31, 2011
	Gross carrying amount			Accumulated impairment			Net carrying amount			Gross carrying amount		Accumulated impairment			Net carrying amount
Balance, beginning of period	$	10,911		$	(7,694	)	$	3,217		$	10,626	$	(2,494	)	$	8,132
Impairment associated with continuing operations	—			(118		)	(118		)	—		(5,200		)	(5,200		)
Reclassified balance associated with discontinued operations (a)	(112		)	—			(112		)	—		—			—
Business combination	—			—			—			285		—			285
Balance, end of period	$	10,799		$	(7,812	)	$	2,987		$	10,911	$	(7,694	)	$	3,217

Schedule of carrying value of ADTI trade name attributed to the U.S. operations of drilling management services segment

	Year ended December 31, 2012									Year ended December 31, 2011
	Gross carrying amount			Accumulated impairment			Net carrying amount			Gross carrying amount		Accumulated impairment			Net carrying amount
Trade name
Balance, beginning of period	$	76		$	(37	)	$	39		$	76	$	(37	)	$	39
Reclassified balance associated with discontinued operations (a)	(76		)	37			(39		)	—		—			—
Balance, end of period	$	—		$	—		$	—		$	76	$	(37	)	$	39

Schedule of carrying amounts of definite-lived intangible asset and intangible liabilities and accumulated amortization and impairment

The gross carrying amounts of our drilling contract intangibles and drilling management customer relationships, both of which we consider to be definite-lived intangible assets and intangible liabilities, and accumulated amortization and impairment were as follows (in millions):

	Year ended December 31, 2012									Year ended December 31, 2011
	Gross carrying amount			Accumulated amortization and impairment			Net carrying amount			Gross carrying amount		Accumulated amortization and impairment			Net carrying amount
Drilling contract intangible assets
Balance, beginning of period	$	191		$	(191	)	$	—		$	191	$	(185	)	$	6
Amortization	—			—			—			—		(6		)	(6		)
Reclassified balance associated with discontinued operations (a)	(182		)	182			—			—		—			—
Balance, end of period	9			9			—			191		(191		)	—

Customer relationships
Balance, beginning of period	148			(94		)	54			148		(89		)	59
Amortization	—			(1		)	(1		)	—		(5		)	(5		)
Impairment associated with continuing operations	—			(22		)	(22		)	—		—			—
Reclassified balance associated with discontinued operations (b)	(88		)	57			(31		)	—		—			—
Balance, end of period	60			(60		)	—			148		(94		)	54

Total definite-lived intangible assets
Balance, beginning of period	339			(285		)	$	54		339		(274		)	65
Amortization	—			(1		)	(1		)	—		(11		)	(11		)
Impairment associated with continuing operations	—			(22		)	(22		)	—		—			—
Reclassified balance associated with discontinued operations (b)	(270		)	239			(31		)	—		—			—
Balance, end of period	$	69		$	(69	)	$	—		$	339	$	(285	)	$	54

Drilling contract intangible liabilities
Balance, beginning of period	$	1,494		$	(1,393	)	$	101		$	1,494	$	(1,342	)	$	152
Amortization	—			(42		)	(42		)	—		(51		)	(51		)
Reclassified balance associated with discontinued operations (a)	(84		)	84			—			—		—			—
Balance, end of period	$	1,410		$	(1,351	)	$	59		$	1,494	$	(1,393	)	$	101

Schedule of estimated future amortization of drilling contract intangible liabilities

At December 31, 2012, the estimated future amortization of our drilling contract intangible liabilities was as follows (in millions):

	Drilling contract intangible liabilities
Years ending December 31,
2013	$	24
2014	15
2015	14
2016	6
Total intangible liabilities	$	59

- Definition

Tabular disclosure of goodwill by reportable segment and in total which includes a rollforward schedule.

+ References+ Details

Debt (Tables)

12 Months Ended

Dec. 31, 2012

Debt

Debt, net of unamortized discounts, premiums and fair value adjustments

Debt, net of unamortized discounts, premiums and fair value adjustments, was comprised of the following (in millions):

	December 31, 2012						December 31, 2011
	Transocean Ltd. and subsidiaries		Consolidated variable interest entities		Consolidated total		Transocean Ltd. and subsidiaries		Consolidated variable interest entities		Consolidated total
5% Notes due February 2013	$	250	$	—	$	250	$	253	$	—	$	253
5.25% Senior Notes due March 2013 (a)	502		—		502		507		—		507
TPDI Credit Facilities due March 2015	403		—		403		—		473		473
4.95% Senior Notes due November 2015 (a)	1,118		—		1,118		1,120		—		1,120
Aker Revolving Credit and Term Loan Facility due December 2015	—		—		—		594		—		594
Callable Bonds due February 2016	282		—		282		267		—		267
5.05% Senior Notes due December 2016 (a)	999		—		999		999		—		999
2.5% Senior Notes due October 2017 (a)	748		—		748		—		—		—
ADDCL Credit Facilities due December 2017	—		191		191		—		217		217
Eksportfinans Loans due January 2018	797		—		797		884		—		884
6.00% Senior Notes due March 2018 (a)	998		—		998		998		—		998
7.375% Senior Notes due April 2018 (a)	247		—		247		247		—		247
TPDI Notes due October 2019	—		—		—		—		148		148
6.50% Senior Notes due November 2020 (a)	899		—		899		899		—		899
6.375% Senior Notes due December 2021 (a)	1,199		—		1,199		1,199		—		1,199
3.8% Senior Notes due October 2022 (a)	745		—		745		—		—		—
7.45% Notes due April 2027 (a)	97		—		97		97		—		97
8% Debentures due April 2027 (a)	57		—		57		57		—		57
7% Notes due June 2028	311		—		311		311		—		311
Capital lease contract due August 2029	657		—		657		676		—		676
7.5% Notes due April 2031 (a)	598		—		598		598		—		598
1.50% Series B Convertible Senior Notes due December 2037 (a)	—		—		—		30		—		30
1.50% Series C Convertible Senior Notes due December 2037 (a)	62		—		62		1,663		—		1,663
6.80% Senior Notes due March 2038 (a)	999		—		999		999		—		999
7.35% Senior Notes due December 2041 (a)	300		—		300		300		—		300
Total debt	12,268		191		12,459		12,698		838		13,536
Less debt due within one year
5% Notes due February 2013	250		—		250		—		—		—
5.25% Senior Notes due March 2013 (a)	502		—		502		—		—		—
TPDI Credit Facilities due March 2015	70		—		70		—		70		70
Aker Revolving Credit and Term Loan Facility due December 2015	—		—		—		90		—		90
Callable Bonds due February 2016	282		—		282		—		—		—
ADDCL Credit Facilities due December 2017	—		28		28		—		27		27
Eksportfinans Loans due January 2018	153		—		153		142		—		142
TPDI Notes due October 2019	—		—		—		—		148		148
Capital lease contract due August 2029	20		—		20		17		—		17
1.50% Series B Convertible Senior Notes due December 2037 (a)	—		—		—		30		—		30
1.50% Series C Convertible Senior Notes due December 2037 (a)	62		—		62		1,663		—		1,663
Total debt due within one year	1,339		28		1,367		1,942		245		2,187
Total long-term debt	$	10,929	$	163	$	11,092	$	10,756	$	593	$	11,349

Scheduled maturities of debt

At December 31, 2012, the scheduled maturities of our debt were as follows (in millions):

	Transocean Ltd. and subsidiaries		Consolidated variable interest entities		Consolidated total
Years ending December 31,
2013	$	1,053	$	28	$	1,081
2014	244		30		274
2015	1,539		61		1,600
2016	1,448		35		1,483
2017	930		37		967
Thereafter	7,032		—		7,032
Total debt, excluding unamortized discounts, premiums and fair value adjustments	12,246		191		12,437
Total unamortized discounts, premiums and fair value adjustments	22		—		22
Total debt	$	12,268	$	191	$	12,459

Carrying amounts of liability components of outstanding convertible senior notes

The carrying amounts of the liability components of the outstanding Convertible Senior Notes were as follows (in millions):

	December 31, 2012						December 31, 2011
	Principal amount		Unamortized discount		Carrying amount		Principal amount		Unamortized discount			Carrying amount
Carrying amount of liability component
Series B Convertible Senior Notes due 2037	$	—	$	—	$	—	$	30	$	—		$	30
Series C Convertible Senior Notes due 2037	62		—		62		1,722		(59		)	1,663

Carrying amounts of equity components of outstanding convertible senior notes

The carrying amounts of the equity components of the outstanding Convertible Senior Notes were as follows (in millions):

	December 31,
	2012		2011
Carrying amount of equity component
Series B Convertible Senior Notes due 2037	$	—	$	4
Series C Convertible Senior Notes due 2037	10		276

Interest expense, excluding amortization of debt issue costs

Interest expense, excluding amortization of debt issue costs, was as follows (in millions):

	Years ended December 31,
	2012		2011		2010
Interest expense
Series A Convertible Senior Notes due 2037	$	—	$	—	$	58
Series B Convertible Senior Notes due 2037	—		78		98
Series C Convertible Senior Notes due 2037	84		84		98

Derivatives and Hedging (Tables)

12 Months Ended

Dec. 31, 2012

Derivatives designated as hedging instruments

Derivatives designated as hedging and not designated as hedging instruments

Schedule of aggregate notional amounts and the weighted average interest rates associated with derivatives

	Pay					Receive
	Aggregate notional amount		Fixed or variable rate	Weighted average rate		Aggregate notional amount			Fixed or variable rate	Weighted average rate
Interest rate swaps, fair value hedges	$	750	variable	3.5	%	$	750		fixed	5.2	%
Interest rate swaps, cash flow hedges	$	385	fixed	2.4	%	$	385		variable	0.3	%
Cross-currency swaps, cash flow hedges	$	102	fixed	8.9	%	NOK		560	fixed	11.0	%

Schedule of effect on the entity's condensed consolidated statement of operations resulting from derivatives designated as cash flow hedges

The effect on our consolidated statements of operations resulting from derivatives designated as cash flow hedges was as follows (in millions):

		Years ended December 31,
	Statement of operations classification	2012			2011			2010
Loss associated with effective portion	Interest expense, net of amounts capitalized	$	(5	)	$	(11	)	$	(12	)
Gain associated with effective portion	Other, net	6			—			—

Schedule of balance sheet classification and aggregate carrying amount of the entity's derivatives measured at fair value, including accrued interest

The balance sheet classification and aggregate carrying amount of our derivatives designated as hedging instruments, measured at fair value, were as follows (in millions):

		December 31,
	Balance sheet classification	2012		2011
Interest rate swaps, fair value hedges	Other current assets	$	6	$	5
Interest rate swaps, fair value hedges	Other assets	—		31
Interest rate swaps, cash flow hedges	Other long-term liabilities	13		16
Cross-currency swaps, cash flow hedges	Other current assets	1		—
Cross-currency swaps, cash flow hedges	Other assets	1		—
Cross-currency swaps, cash flow hedges	Other long-term liabilities	—		7

Derivative not designated as hedging instruments | Interest rate swaps

Derivatives designated as hedging and not designated as hedging instruments

Schedule of effect on the entity's condensed consolidated statement of operations resulting from derivatives designated as cash flow hedges

The effect on our consolidated statements of operations resulting from changes in the fair values of derivatives not designated as hedging instruments was as follows (in millions):

		Years ended December 31,
	Statement of operations classification	2012			2011			2010
Loss associated with undesignated interest rate swaps	Interest expense, net of amounts capitalized	$	(1	)	$	—		$	—
Loss associated with undesignated forward exchange contract	Other, net	—			(78		)	—

Schedule of balance sheet classification and aggregate carrying amount of the entity's derivatives measured at fair value, including accrued interest

The balance sheet classification and aggregate carrying amount of our derivatives not designated as hedging instruments, measured at fair value, were as follows (in millions):

		December 31,
	Balance sheet classification	2012		2011
Interest rate swaps not designated as hedging instruments	Other long-term liabilities	$	—	$	15
Embedded derivatives not designated as hedging instruments	Other long-term liabilities	2		—

- Definition

Tabular disclosure of the location and amount of gains and losses reported in the statement of financial performance, or when applicable, the statement of financial position. For example, (a) gains and losses recognized in the income statement on derivative instruments designated and qualifying as hedging instruments in fair value hedges and related hedged items designated and qualifying in fair value hedges and (b) gains and losses initially recognized in other comprehensive income on derivative instruments designated and qualifying as cash flow hedges.

+ References+ Details

- Definition

Tabular disclosure of the location and fair value amounts of derivative instruments (and nonderivative instruments that are designated and qualify as hedging instruments) reported in the statement of financial position.

+ References+ Details

- Definition

Tabular disclosure of pertinent information about a derivative or group of derivatives on a disaggregated basis, such as for individual instruments, or small groups of similar instruments. May include a combination of the type of instrument, risks being hedged, notional amount, hedge designation, related hedged item, inception date, maturity date, or other relevant item.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

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-Name Accounting Standards Codification

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-Section 50

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-Subparagraph (SX 210.4-08.(n)(2))

-URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690

+ Details

Postemployment Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2012

Postemployment Benefit Plans

Schedule of weighted-average assumptions used to determine benefit obligations

	December 31, 2012						December 31, 2011
	U.S. Plans		Non-U.S. Plans		OPEB Plans		U.S. Plans		Non-U.S. Plans		OPEB Plans
Discount rate	4.19	%	5.37	%	3.63	%	4.66	%	4.90	%	4.28	%
Compensation trend rate	4.21	%	4.38	%	n/a		4.22	%	4.30	%	n/a

Schedule of weighted-average assumptions used to determine net periodic benefit costs

	Year ended December 31, 2012						Year ended December 31, 2011						Year ended December 31, 2010
	U.S. Plans		Non-U.S. Plans		OPEB Plans		U.S. Plans		Non-U.S. Plans		OPEB Plans		U.S. Plans		Non-U.S. Plans		OPEB Plans
Discount rate	4.67	%	5.43	%	4.27	%	5.49	%	5.73	%	4.94	%	5.86	%	5.67	%	5.51	%
Expected rate of return	7.47	%	6.07	%	n/a		8.49	%	6.42	%	n/a		8.49	%	6.65	%	n/a
Compensation trend rate	4.22	%	4.61	%	n/a		4.24	%	4.62	%	n/a		4.21	%	4.77	%	n/a
Health care cost trend rate
-initial	n/a		n/a		8.08	%	n/a		n/a		8.08	%	n/a		n/a		8.00	%
-ultimate	n/a		n/a		5.00	%	n/a		n/a		5.00	%	n/a		n/a		5.00	%
-ultimate year	n/a		n/a		2019		n/a		n/a		2018		n/a		n/a		2016

“n/a” means not applicable.

Schedule of changes in projected benefit obligation, plan assets and funded status and the amounts recognized on consolidated balance sheets

The changes in projected benefit obligation, plan assets and funded status and the amounts recognized on our consolidated balance sheets were as follows (in millions):

	Year ended December 31, 2012												Year ended December 31, 2011
	U.S. Plans			Non-U.S. Plans			OPEB Plans			Total			U.S. Plans			Non-U.S. Plans			OPEB Plans			Total
Change in projected benefit obligation
Projected benefit obligation, beginning of period	$	1,260		$	447		$	53		$	1,760		$	1,068		$	374		$	56		$	1,498
Assumed projected benefit obligation	—			—			—			—			—			17			—			17
Actuarial (gains) losses, net	128			(15		)	4			117			128			24			(3		)	149
Service cost	49			31			1			81			43			21			1			65
Interest cost	59			24			2			85			58			22			3			83
Foreign currency exchange rate	—			19			—			19			—			(1		)	—			(1		)
Benefits paid	(45		)	(23		)	(3		)	(71		)	(37		)	(12		)	(5		)	(54		)
Participant contributions	—			2			1			3			—			2			1			3
Special termination benefits	1			—			—			1			—			—			—			—
Settlements and curtailments	—			14			—			14			—			—			—			—
Projected benefit obligation, end of period	1,452			499			58			2,009			1,260			447			53			1,760

Change in plan assets
Fair value of plan assets, beginning of period	769			351			—			1,120			697			332			—			1,029
Fair value of acquired plan assets	—			—			—			—			—			9			—			9
Actual return on plan assets	116			28			—			144			39			(8		)	—			31
Foreign currency exchange rate changes	—			15			—			15			—			2			—			2
Employer contributions	108			49			2			159			70			29			4			103
Participant contributions	—			2			1			3			—			2			1			3
Benefits paid	(45		)	(23		)	(3		)	(71		)	(37		)	(12		)	(5		)	(54		)
Settlement and curtailments	—			—			—			—			—			(3		)	—			(3		)
Fair value of plan assets, end of period	948			422			—			1,370			769			351			—			1,120

Funded status, end of period	$	(504	)	$	(77	)	$	(58	)	$	(639	)	$	(491	)	$	(96	)	$	(53	)	$	(640	)

Balance sheet classification, end of period:
Pension asset, non-current	$	—		$	3		$	—		$	3		$	—		$	—		$	—		$	—
Accrued pension liability, current	3			24			3			30			3			5			3			11
Accrued pension liability, non-current	501			56			55			612			488			91			50			629
Accumulated other comprehensive income (loss) (a)	(469		)	(80		)	(6		)	(555		)	(437		)	(111		)	(2		)	(550		)

(a) Amounts are before income tax effect.

Schedule of aggregate projected benefit obligation and fair value of plan assets for plans with a projected benefit obligation in excess of plan assets

The aggregate projected benefit obligation and fair value of plan assets for plans with a projected benefit obligation in excess of plan assets were as follows (in millions):

	December 31, 2012								December 31, 2011
	U.S. Plans		Non-U.S. Plans		OPEB Plans		Total		U.S. Plans		Non-U.S. Plans		OPEB Plans		Total
Projected benefit obligation	$	1,452	$	482	$	58	$	1,992	$	1,260	$	447	$	53	$	1,760
Fair value of plan assets	948		404		—		1,352		769		351		—		1,120

Schedule of aggregate accumulated benefit obligation and fair value of plan assets for plans with an accumulated benefit obligation in excess of plan assets

The aggregate accumulated benefit obligation and fair value of plan assets for plans with an accumulated benefit obligation in excess of plan assets were as follows (in millions):

	December 31, 2012								December 31, 2011
	U.S. Plans		Non-U.S. Plans		OPEB Plans		Total		U.S. Plans		Non-U.S. Plans		OPEB Plans		Total
Accumulated benefit obligation	$	1,255	$	335	$	58	$	1,648	$	1,083	$	288	$	53	$	1,424
Fair value of plan assets	948		298		—		1,246		769		254		—		1,023

Schedule of weighted average target and actual allocations of the investments of Transocean benefit plans

					Actual allocation at December 31,
	Target allocation				2012				2011
	U.S. Plans		Non-U.S. Plans		U.S. Plans		Non-U.S. Plans		U.S. Plans		Non-U.S. Plans
Equity securities	65	%	49	%	64	%	49	%	64	%	47	%
Fixed income securities	35	%	14	%	36	%	17	%	36	%	12	%
Other investments	—		37	%	—		34	%	—		41	%
Total	100	%	100	%	100	%	100	%	100	%	100	%

Schedule of fair value of the assets of Transocean benefit plans by asset category and their level within the fair value hierarchy

As of December 31, 2012, the investments for our funded Transocean Plans were categorized as follows (in millions):

	December 31, 2012
	Significant observable inputs						Significant other observable inputs						Total
	U.S. Plans		Non-U.S. Plans		Transocean Plans		U.S. Plans		Non-U.S. Plans		Transocean Plans		U.S. Plans		Non-U.S. Plans		Transocean Plans
Mutual funds
U.S. equity funds	$	525	$	—	$	525	$	—	$	32	$	32	$	525	$	32	$	557
Non-U.S. equity funds	120		—		120		3		176		179		123		176		299
Bond funds	296		—		296		—		73		73		296		73		369
Total mutual funds	941		—		941		3		281		284		944		281		1,225

Other investments
Cash and money market funds	4		2		6		—		6		6		4		8		12
Property collective trusts	—		—		—		—		8		8		—		8		8
Investment contracts	—		—		—		—		125		125		—		125		125
Total other investments	4		2		6		—		139		139		4		141		145

Total investments	$	945	$	2	$	947	$	3	$	420	$	423	$	948	$	422	$	1,370

As of December 31, 2011, the investments for our funded Transocean Plans were categorized as follows (in millions):

	December 31, 2011
	Significant observable inputs						Significant other observable inputs						Total
	U.S. Plans		Non-U.S. Plans		Transocean Plans		U.S. Plans		Non-U.S. Plans		Transocean Plans		U.S. Plans		Non-U.S. Plans		Transocean Plans
Mutual funds
U.S. equity funds	$	395	$	—	$	395	$	—	$	29	$	29	$	395	$	29	$	424
Non-U.S. equity funds	91		—		91		2		137		139		93		137		230
Bond funds	278		—		278		—		43		43		278		43		321
Total mutual funds	764		—		764		2		209		211		766		209		975

Other investments
Cash and money market funds	3		38		41		—		—		—		3		38		41
Property collective trusts	—		—		—		—		8		8		—		8		8
Investment contracts	—		—		—		—		96		96		—		96		96
Total other investments	3		38		41		—		104		104		3		142		145

Total investments	$	767	$	38	$	805	$	2	$	313	$	315	$	769	$	351	$	1,120

Net Periodic Benefit Costs Before Tax

Net periodic benefit costs, before tax, included the following components (in millions):

	Year ended December 31, 2012									Year ended December 31, 2011									Year ended December 31, 2010
	U.S. Plans			Non-U.S. Plans			Transocean Plans			U.S. Plans			Non-U.S. Plans			Transocean Plans			U.S. Plans			Non-U.S. Plans			Transocean Plans
Service cost	$	49		$	31		$	80		$	43		$	21		$	64		$	42		$	20		$	62
Interest cost	59			24			83			58			22			80			54			20			74
Expected return on plan assets	(62		)	(22		)	(84		)	(63		)	(23		)	(86		)	(58		)	(17		)	(75		)
Settlements and curtailments	3			19			22			2			1			3			5			3			8
Special termination benefits	1			—			1			—			—			—			3			—			3
Actuarial losses, net	41			4			45			23			4			27			13			4			17
Prior service cost (credit), net	(2		)	1			(1		)	(1		)	—			(1		)	(1		)	—			(1		)
Transition obligation, net	—			—			—			—			—			—			—			1			1
Net periodic benefit costs	$	89		$	57		$	146		$	62		$	25		$	87		$	58		$	31		$	89

Schedule of amounts in accumulated other comprehensive income, before tax, that have not been recognized as components of net periodic benefit costs

The following table presents the amounts in accumulated other comprehensive income, before tax, that have not been recognized as components of net periodic benefit costs (in millions):

	December 31, 2012											December 31, 2011
	U.S. Plans			Non-U.S. Plans		OPEB Plans			Total			U.S. Plans			Non-U.S. Plans			OPEB Plans			Total
Actuarial loss, net	$	477		$	80	$	8		$	565		$	447		$	113		$	4		$	564
Prior service cost (credit), net	(8		)	—		(2		)	(10		)	(10		)	—			(2		)	(12		)
Transition obligation, net	—			—		—			—			—			(2		)	—			(2		)
Total	$	469		$	80	$	6		$	555		$	437		$	111		$	2		$	550

Schedule of amounts in accumulated other comprehensive income expected to be recognized as components of net periodic benefit costs in next fiscal year

	Year ending December 31, 2013
	U.S. Plans			Non-U.S. Plans		OPEB Plans			Total
Actuarial loss, net	$	48		$	4	$	1		$	53
Prior service cost (credit), net	(1		)	—		(1		)	(2		)
Transition obligation, net	—			—		—			—
Total amount expected to be recognized	$	47		$	4	$	—		$	51

Schedule of projected benefits payments

The following were the projected benefits payments (in millions):

	U.S. Plans		Non-U.S. Plans		OPEB Plans		Total
Years ending December 31,
2013	$	43	$	28	$	4	$	75
2014	47		11		4		62
2015	51		10		4		65
2016	55		11		4		70
2017	59		11		4		74
2018-2022	349		82		22		453

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2012

Commitments and Contingencies

Schedule of future minimum rental payments related to noncancellable operating leases and the capital leases

As of December 31, 2012, future minimum rental payments related to non-cancellable operating leases and the capital lease were as follows (in millions):

	Capital lease			Operating leases
Years ending December 31,
2013	$	66		$	42
2014	72			38
2015	72			24
2016	72			21
2017	73			11
Thereafter	846			95
Total future minimum rental payment	$	1,201		$	231
Less amount representing imputed interest	(544		)
Present value of future minimum rental payments under capital leases	657
Less current portion included in debt due within one year	(20		)
Long-term capital lease obligation	$	637

Schedule of aggregate carrying amount of assets held under capital lease

At December 31, 2012 and 2011, the aggregate carrying amount of our assets held under capital lease was as follows (in millions):

	December 31,
	2012			2011
Property and equipment, cost	$	745		$	742
Accumulated depreciation	(64		)	(44		)
Property and equipment, net	$	681		$	698

Schedule of purchase obligations

At December 31, 2012, our purchase obligations, primarily related to our newbuilds, were as follows (in millions):

	Purchase obligations
Years ending December 31,
2013	$	1,896
2014	447
2015	749
2016	674
2017	—
Thereafter	—
Total	$	3,766

- Definition

Tabular disclosure of unconditional purchase obligations that are not recognized as a liability on the balance sheet, including the nature and significant terms of an unconditional purchase obligation; the amount of the fixed and determinable portion of the obligation as of the date of the latest balance sheet presented in the aggregate and, if determinable, for each of the five succeeding fiscal years; the nature of any variable components of the obligation; the amount purchased under the obligation (for example, the take-or-pay or throughput contract) for the reporting period; and may include the amount of imputed interest necessary to reduce the obligation to present value.

+ References+ Details

Redeemable Noncontrolling Interest (Tables)

12 Months Ended

Dec. 31, 2012

Redeemable Noncontrolling Interest

Changes in redeemable noncontrolling interest

Changes in redeemable noncontrolling interest were as follows (in millions):

	Years ended December 31,
	2012			2011			2010
Redeemable noncontrolling interest
Balance, beginning of period	$	116		$	41		$	—
Reclassification from noncontrolling interest	—			—			26
Net income attributable to noncontrolling interest	13			78			29
Other comprehensive loss attributable to noncontrolling interest	—			(3		)	(14		)
Fair value adjustment to redeemable noncontrolling interest	106			—			—
Reclassification to accumulated other comprehensive loss	17			—			—
Reclassification to other current liabilities	(252		)	—			—
Balance, end of period	$	—		$	116		$	41

- Definition

Tabular disclosure of redeemable noncontrolling interest (as defined) included in the statement of financial position as either a liability or temporary equity. As of the date of the statement of financial position, such redeemable noncontrolling interest is currently redeemable, as defined, for cash or other assets of the entity at (1) at a fixed or determinable price on a fixed or determinable date, (2) at the option of the holder of the noncontrolling interest, or (3) upon occurrence of an event that is not solely within the control of the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number D-98

-Paragraph 44

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number D-98

-Paragraph 43

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number D-98

-Paragraph 40

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number D-98

-Paragraph 41

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number D-98

-Paragraph 42

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

-Paragraph 25

-Appendix A

+ Details

Shareholders' Equity (Tables)

12 Months Ended

Dec. 31, 2012

Shareholders' Equity

Changes in accumulated other comprehensive income

The changes in accumulated other comprehensive loss for the years ended December 31, 2012 and 2011 were as follows (in millions):

	Year ended December 31, 2012												Year ended December 31, 2011
	Unrecognized components of net periodic benefit costs			Unrecognized gains (losses) on derivative instruments			Unrecognized gains (losses) on marketable securities			Total			Unrecognized components of net periodic benefit costs			Unrecognized gains (losses) on derivative instruments		Unrecognized gains (losses) on marketable securities			Total
Balance, beginning of period	$	(501	)	$	7		$	(2	)	$	(496	)	$	(335	)	$	5	$	(2	)	$	(332	)
Reclassification from redeemable noncontrolling interest	—			(17		)	—			(17		)	—			—		—			—
Other comprehensive income (loss) attributable to controlling interest	(10		)	—			2			(8		)	(166		)	2		—			(164		)
Balance, end of period	$	(511	)	$	(10	)	$	—		$	(521	)	$	(501	)	$	7	$	(2	)	$	(496	)

Share-Based Compensation Plans (Tables)

12 Months Ended

Dec. 31, 2012

Share Based Compensation Plans

Schedule of weighted-average assumption for option valuation

	Years ended December 31,
	2012			2011			2010
Dividend yield	—			4		%	4		%
Expected price volatility	43		%	40		%	39		%
Risk-free interest rate	0.87		%	1.97		%	2.30		%
Expected life of options	5.0 years			4.9 years			4.7 years
Weighted-average fair value of options granted	$	18.87		$	19.75		$	30.03

Summary of activity for stock appreciation rights outstanding

	Number of awards	Weighted-average exercise price per share		Weighted-average remaining contractual term (years)	Aggregate intrinsic value (in millions)
Outstanding at January 1, 2012	187,739	$	93.39	4.76	$	—
Outstanding at December 31, 2012	187,739	$	93.39	3.76	$	—

Vested and exercisable at December 31, 2012	187,739	$	93.39	3.76	$	—

Time-Based Awards

Share Based Compensation Plans

Summary of unvested deferred units activity

	Number of units		Weighted-average grant-date fair value per share
Unvested at January 1, 2012	1,939,840		$	74.78
Granted	2,183,853		50.07
Vested	(1,064,359	)	71.57
Forfeited	(189,283	)	60.73
Unvested at December 31, 2012	2,870,051		$	58.09

Summary of activity for vested and unvested stock options outstanding

	Number of shares under option		Weighted-average exercise price per share		Weighted-average remaining contractual term (years)	Aggregate intrinsic value (in millions)
Outstanding at January 1, 2012	1,579,284		$	70.16	5.43	$	—
Granted	395,673		50.79
Exercised	(264,707	)	36.50
Forfeited	(55,533	)	59.65
Expired	(38,662	)	53.51
Outstanding at December 31, 2012	1,616,055		$	71.69	6.30	$	—

Vested and exercisable at December 31, 2012	1,088,127		$	77.24	5.15	$	—

Market-Based Awards

Share Based Compensation Plans

Summary of unvested deferred units activity

	Number of units		Weighted-average grant-date fair value per share
Unvested at January 1, 2012	415,947		$	75.98
Granted	163,319		58.52
Vested	(318,926	)	75.18
Forfeited	(28,889	)	70.04
Unvested at December 31, 2012	231,451		$	65.50

Performance-Based Awards

Share Based Compensation Plans

Summary of activity for vested and unvested stock options outstanding

	Number of shares under option	Weighted-average exercise price per share		Weighted-average remaining contractual term (years)	Aggregate intrinsic value (in millions)
Outstanding at January 1, 2012	179,262	$	75.30	4.23	$	—
Outstanding at December 31, 2012	179,262	$	75.30	3.22	$	—

Vested and exercisable at December 31, 2012	179,262	$	75.30	3.22	$	—

Supplemental Balance Sheet Information (Tables)

12 Months Ended

Dec. 31, 2012

Supplemental Balance Sheet Information

Schedule of other current liabilities

Other current liabilities were comprised of the following (in millions):

	December 31,
	2012		2011
Other current liabilities
Accrued payroll and employee benefits	$	421	$	328
Distribution payable	—		278
Deferred revenue	214		171
Deferred revenue of consolidated variable interest entities	21		16
Accrued taxes, other than income	150		142
Accrued interest	122		132
Contingent liabilities	1,958		1,243
Other	47		65
Total other current liabilities	$	2,933	$	2,375

Schedule of other long term liabilities

Other long-term liabilities were comprised of the following (in millions):

	December 31,
	2012		2011
Other long-term liabilities
Long-term income taxes payable	$	584	$	751
Accrued pension liabilities	558		579
Deferred revenue	174		236
Deferred revenue of consolidated variable interest entities	72		85
Drilling contract intangibles	60		103
Accrued retiree life insurance and medical benefits	54		49
Other	102		122
Total other long-term liabilities	$	1,604	$	1,925

Supplemental Cash Flow Information (Tables)

12 Months Ended

Dec. 31, 2012

Supplemental Cash Flow Information

Schedule of changes in operating assets and liabilities

Net cash provided by operating activities attributable to the net change in operating assets and liabilities were composed of the following (in millions):

	Years ended December 31,
	2012			2011			2010
Changes in operating assets and liabilities
Decrease (increase) in accounts receivable	$	(139	)	$	(174	)	$	386
Increase in other current assets	(73		)	(73		)	(75		)
Decrease (increase) in other assets	12			26			(40		)
Increase in accounts payable and other current liabilities	931			978			197
Decrease in other long-term liabilities	(63		)	(34		)	(52		)
Change in income taxes receivable / payable, net	(156		)	80			(37		)
	$	512		$	803		$	379

Additional cash flow information

Additional cash flow information were as follows (in millions):

	Years ended December 31,
	2012		2011		2010
Certain cash operating activities
Cash payments for interest	$	719	$	501	$	455
Cash payments for income taxes	347		338		493

Non-cash investing and financing activities
Capital expenditures, accrued at end of period (a)	$	123	$	62	$	66
Issuance of shares in exchange for redeemable noncontrolling interest (b)	367		—		—
Non-cash proceeds received for the sale of assets (c)	194		—		134

(a) These amounts represent additions to property and equipment for which we had accrued a corresponding liability in accounts payable.

(b) On May 31, 2012, we issued 8.7 million shares to Quantum in a non-cash exchange for its interest in TPDI. See Note 18—Redeemable Noncontrolling Interest.

Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2012

Financial Instruments

Carrying amounts and fair values of the financial instruments

	December 31, 2012				December 31, 2011
	Carrying amount		Fair value		Carrying amount		Fair value
Cash and cash equivalents	$	5,134	$	5,134	$	4,017	$	4,017
Notes and other loans receivable	142		142		154		154
Preference shares	196		196		—		—
Restricted cash investments	857		903		934		975
Long-term debt, including current maturities	12,268		13,899		12,698		13,074
Long-term debt of consolidated variable interest entities, including current maturities	191		191		838		838
Derivative instruments, assets	8		8		36		36
Derivative instruments, liabilities	15		15		38		38

- Definition

Tabular disclosure of the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments, assets, and liabilities. Such certain disclosures about the financial instruments, assets, and liabilities include: (1) the fair value of the required items together with their carrying amounts (as appropriate) and (2) the methodology and assumptions used in developing such estimates of fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 159

-Paragraph 18

-Subparagraph c(2), d, e, f

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 157

-Paragraph 32

-Subparagraph a, c(1), c(2), c(3), d

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=7578670&loc=d3e19207-110258

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13433-108611

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 11

-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13467-108611

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13476-108611

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 107

-Paragraph 10

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Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 30

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6957238&loc=d3e14172-108612

Reference 9: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 107

-Paragraph 14

-Subparagraph a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 10: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6447952&loc=d3e13220-108610

Reference 11: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 159

-Paragraph 19

-Subparagraph a, b, c(1), d(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 12: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 107

-Paragraph 15

-Subparagraph b-d

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Operating Segments, Geographic Analysis and Major Customers (Tables)

12 Months Ended

Dec. 31, 2012

Operating Segments, Geographic Analysis and Major Customers

Schedule of operating revenues for continuing operations by country

Operating revenues for our continuing operations by country were as follows (in millions):

	Years ended December 31,
	2012		2011		2010
Operating revenues
U.S.	$	2,472	$	1,971	$	1,937
Norway	1,174		897		765
Brazil	1,114		1,019		1,288
U.K.	1,028		1,099		1,097
Other countries (a)	3,408		3,041		2,862
Total operating revenues	$	9,196	$	8,027	$	7,949

(a) Other countries represents countries in which we operate that individually had operating revenues representing less than 10 percent of total operating revenues earned.

Schedule of long-lived assets by country

Long-lived assets by country were as follows (in millions):

	December 31,
	2012		2011
Long-lived assets
U.S.	$	7,395	$	6,553
Brazil	2,285		2,185
Norway	2,072		2,067
Other countries (a)	9,128		9,983
Total long-lived assets	$	20,880	$	20,788

(a) Other countries represents countries in which we operate that individually had long-lived assets representing less than 10 percent of total long-lived assets.

- Definition

Tabular disclosure of the names of foreign countries from which revenue is material and the amount of revenue from external customers attributed to those countries. An entity may also provide subtotals of geographic information about groups of countries.

+ References+ Details

Condensed Consolidating Financial Information (Tables)

12 Months Ended

Dec. 31, 2012

Condensed Consolidating Financial Information

Schedule of condensed consolidating statement of operations

	Year ended December 31, 2012
	Parent Guarantor			Subsidiary Issuer			Other Subsidiaries			Consolidating adjustments			Consolidated
							(in millions)
Operating revenues	$	—		$	5		$	9,213		$	(22	)	$	9,196
Cost and expenses	54			16			7,463			(22		)	7,511
Loss on impairment	—			—			(140		)	—			(140		)
Gain on disposal of assets, net	—			—			36			—			36
Operating income (loss)	(54		)	(11		)	1,646			—			1,581

Other income (expense), net
Interest expense, net	(12		)	(576		)	(79		)	—			(667		)
Equity in earnings	(153		)	402			—			(249		)	—
Other, net	—			(4		)	(44		)	—			(48		)
	(165		)	(178		)	(123		)	(249		)	(715		)
Income (loss) from continuing operations before income tax expense	(219		)	(189		)	1,523			(249		)	866
Income tax expense	—			—			50			—			50
Income (loss) from continuing operations	(219		)	(189		)	1,473			(249		)	816
Loss from discontinued operations, net of tax	—			—			(1,027		)	—			(1,027		)

Net income (loss)	(219		)	(189		)	446			(249		)	(211		)
Net income (loss) attributable to noncontrolling interest	—			—			8			—			8
Net income (loss) attributable to controlling interest	(219		)	(189		)	438			(249		)	(219		)

Other comprehensive income (loss) before income taxes	(5		)	(31		)	35			—			(1		)
Income taxes related to other comprehensive income (loss)	—			—			(7		)	—			(7		)
Other comprehensive income (loss), net of income taxes	(5		)	(31		)	28			—			(8		)

Total comprehensive income (loss)	(224		)	(220		)	474			(249		)	(219		)
Total comprehensive income (loss) attributable to noncontrolling interest	—			—			8			—			8
Total comprehensive income (loss) attributable to controlling interest	$	(224	)	$	(220	)	$	466		$	(249	)	$	(227	)

	Year ended December 31, 2011
	Parent Guarantor			Subsidiary Issuer			Other Subsidiaries			Consolidating adjustments			Consolidated

Operating revenues	$	—		$	—		$	8,045		$	(18	)	$	8,027
Cost and expenses	44			4			7,546			(18		)	7,576
Loss on impairment	—			—			(5,201		)	—			(5,201		)
Loss on disposal of assets, net	—			—			(12		)	—			(12		)
Operating loss	(44		)	(4		)	(4,714		)	—			(4,762		)

Other income (expense), net
Interest expense, net	(11		)	(510		)	(56		)	—			(577		)
Equity in earnings	(5,699		)	(5,174		)	—			10,873			—
Other, net	—			9			(108		)	—			(99		)
	(5,710		)	(5,675		)	(164		)	10,873			(676		)
Loss from continuing operations before income tax expense	(5,754		)	(5,679		)	(4,878		)	10,873			(5,438		)
Income tax expense	—			—			324			—			324
Loss from continuing operations	(5,754		)	(5,679		)	(5,202		)	10,873			(5,762		)
Income from discontinued operations, net of tax	—			—			85			—			85

Net loss	(5,754		)	(5,679		)	(5,117		)	10,873			(5,677		)
Net income attributable to noncontrolling interest	—			—			77			—			77
Net loss attributable to controlling interest	(5,754		)	(5,679		)	(5,194		)	10,873			(5,754		)

Other comprehensive income (loss) before income taxes	(3		)	(114		)	(64		)	—			(181		)
Income taxes related to other comprehensive income (loss)	—			—			13			—			13
Other comprehensive income (loss), net of income taxes	(3		)	(114		)	(51		)	—			(168		)

Total comprehensive income (loss)	(5,757		)	(5,793		)	(5,168		)	10,873			(5,845		)
Total comprehensive income attributable to noncontrolling interest	—			—			73			—			73
Total comprehensive income (loss) attributable to controlling interest	$	(5,757	)	$	(5,793	)	$	(5,241	)	$	10,873		$	(5,918	)

	Year ended December 31, 2010
	Parent Guarantor			Subsidiary Issuer			Other Subsidiaries			Consolidating adjustments			Consolidated

Operating revenues	$	—		$	—		$	7,964		$	(15	)	$	7,949
Cost and expenses	45			3			5,441			(15		)	5,474
Gain on disposal of assets, net	—			—			255			—			255
Operating income (loss)	(45		)	(3		)	2,778			—			2,730

Other income (expense), net
Interest expense, net	1			(494		)	(51		)	—			(544		)
Equity in earnings	970			1,484			—			(2,454		)	—
Other, net	—			(7		)	(24		)	—			(31		)
	971			983			(75		)	(2,454		)	(575		)
Income from continuing operations before income tax expense	926			980			2,703			(2,454		)	2,155
Income tax expense	—			—			292			—			292
Income from continuing operations	926			980			2,411			(2,454		)	1,863
Loss from discontinued operations, net of tax	—			—			(894		)	—			(894		)

Net income	926			980			1,517			(2,454		)	969
Net income attributable to noncontrolling interest	—			—			43			—			43
Net income attributable to controlling interest	926			980			1,474			(2,454		)	926

Other comprehensive income (loss) before income taxes	7			(44		)	28			—			(9		)
Income taxes related to other comprehensive income (loss)	—			—			(9		)	—			(9		)
Other comprehensive income (loss), net of income taxes	7			(44		)	19			—			(18		)

Total comprehensive income	933			936			1,536			(2,454		)	951
Total comprehensive income attributable to noncontrolling interest	—			—			22			—			22
Total comprehensive income attributable to controlling interest	$	933		$	936		$	1,514		$	(2,454	)	$	929

Schedule of condensed consolidating balance sheet

	December 31, 2012
	Parent Guarantor		Subsidiary Issuer		Other Subsidiaries		Consolidating adjustments			Consolidated

Assets
Cash and cash equivalents	$	24	$	3,155	$	1,955	$	—		$	5,134
Other current assets	7		1,901		3,852		(2,247		)	3,513
Total current assets	31		5,056		5,807		(2,247		)	8,647

Property and equipment, net	—		—		20,880		—			20,880
Goodwill	—		—		2,987		—			2,987
Investment in affiliates	16,354		27,933		196		(44,287		)	196
Other assets	—		1,804		18,048		(18,307		)	1,545
Total assets	16,385		34,793		47,918		(64,841		)	34,255

Liabilities and equity
Debt due within one year	—		564		803		—			1,367
Other current liabilities	13		632		5,698		(2,247		)	4,096
Total current liabilities	13		1,196		6,501		(2,247		)	5,463

Long-term debt	594		17,772		11,033		(18,307		)	11,092
Other long-term liabilities	33		454		1,483		—			1,970
Total long-term liabilities	627		18,226		12,516		(18,307		)	13,062

Commitments and contingencies
Redeemable noncontrolling interest	—		—		—		—			—

Total equity	15,745		15,371		28,901		(44,287		)	15,730
Total liabilities and equity	$	16,385	$	34,793	$	47,918	$	(64,841	)	$	34,255

	December 31, 2011
	Parent Guarantor		Subsidiary Issuer		Other Subsidiaries		Consolidating adjustments			Consolidated

Assets
Cash and cash equivalents	$	3	$	2,793	$	1,221	$	—		$	4,017
Other current assets	8		784		4,476		(1,749		)	3,519
Total current assets	11		3,577		5,697		(1,749		)	7,536

Property and equipment, net	1		—		20,787		—			20,788
Goodwill	—		—		3,217		—			3,217
Investment in affiliates	16,439		27,518		—		(43,957		)	—
Other assets	—		1,368		20,799		(18,676		)	3,491
Total assets	16,451		32,463		50,500		(64,382		)	35,032

Liabilities and equity
Debt due within one year	—		1,693		494		—			2,187
Other current liabilities	294		367		4,429		(1,749		)	3,341
Total current liabilities	294		2,060		4,923		(1,749		)	5,528

Long-term debt	495		14,308		15,222		(18,676		)	11,349
Other long-term liabilities	25		439		1,948		—			2,412
Total long-term liabilities	520		14,747		17,170		(18,676		)	13,761

Commitments and contingencies
Redeemable noncontrolling interest	—		—		116		—			116

Total equity	15,637		15,656		28,291		(43,957		)	15,627
Total liabilities and equity	$	16,451	$	32,463	$	50,500	$	(64,382	)	$	35,032

Schedule of condensed consolidating statement of cash flows

	Year ended December 31, 2012
	Parent Guarantor			Subsidiary Issuer			Other Subsidiaries			Consolidating adjustments			Consolidated

Cash flows from operating activities	$	(86	)	$	(953	)	$	3,747		$	—		$	2,708

Cash flows from investing activities
Capital expenditures	—			—			(1,303		)	—			(1,303		)
Capital expenditures for discontinued operations	—			—			(106		)	—			(106		)
Proceeds from disposal of assets, net	—			—			191			—			191
Proceeds from disposal of discontinued operations, net	—			568			221			—			789
Investing activities with affiliates, net	(165		)	(2,344		)	(3,726		)	6,235			—
Other, net	—			29			11			—			40
Net cash provided by (used in) investing activities	(165		)	(1,747		)	(4,712		)	6,235			(389		)

Cash flows from financing activities
Changes in short-term borrowings, net	—			—			(260		)	—			(260		)
Proceeds from debt	—			1,493			—			—			1,493
Repayments of debt	—			(1,689		)	(593		)	—			(2,282		)
Proceeds from restricted cash investments	—			—			311			—			311
Deposits to restricted cash investments	—			—			(167		)	—			(167		)
Distribution of qualifying additional paid-in capital	(278		)	—			—			—			(278		)
Financing activities with affiliates, net	549			3,276			2,410			(6,235		)	—
Other, net	1			(18		)	(2		)	—			(19		)
Net cash provided by (used in) financing activities	272			3,062			1,699			(6,235		)	(1,202		)

Net increase (decrease) in cash and cash equivalents	21			362			734			—			1,117
Cash and cash equivalents at beginning of period	3			2,793			1,221			—			4,017
Cash and cash equivalents at end of period	$	24		$	3,155		$	1,955		$	—		$	5,134

	Year ended December 31, 2011
	Parent Guarantor			Subsidiary Issuer			Other Subsidiaries			Consolidating adjustments			Consolidated

Cash flows from operating activities	$	(52	)	$	(568	)	$	2,445		$	—		$	1,825

Cash flows from investing activities
Capital expenditures	—			—			(974		)	—			(974		)
Capital expenditures for discontinued operations	—			—			(46		)	—			(46		)
Investment in business combination, net of cash acquired	—			—			(1,246		)	—			(1,246		)
Proceeds from disposal of assets, net	—			—			14			—			14
Proceeds from disposal of discontinued operations, net	—			—			447			—			447
Investing activities with affiliates, net	(875		)	(325		)	(1,764		)	2,964			—
Other, net	—			(23		)	(68		)	—			(91		)
Net cash provided by (used in) investing activities	(875		)	(348		)	(3,637		)	2,964			(1,896		)

Cash flows from financing activities
Changes in short-term borrowings, net	—			(88		)	—			—			(88		)
Proceeds from debt	435			2,504			—			—			2,939
Repayments of debt	(429		)	(1,827		)	(153		)	—			(2,409		)
Proceeds from restricted cash investments	429			—			50			—			479
Deposits to restricted cash investments	(435		)	—			(88		)	—			(523		)
Proceeds from share issuance, net	1,211			—			—			—			1,211
Distribution of qualifying additional paid-in capital	(763		)	—			—			—			(763		)
Financing activities with affiliates, net	495			1,114			1,355			(2,964		)	—
Other, net	(51		)	(35		)	(26		)	—			(112		)
Net cash provided by (used in) financing activities	892			1,668			1,138			(2,964		)	734

Net increase (decrease) in cash and cash equivalents	(35		)	752			(54		)	—			663
Cash and cash equivalents at beginning of period	38			2,041			1,275			—			3,354
Cash and cash equivalents at end of period	$	3		$	2,793		$	1,221		$	—		$	4,017

	Year ended December 31, 2010
	Parent Guarantor			Subsidiary Issuer			Other Subsidiaries			Consolidating adjustments			Consolidated

Cash flows from operating activities	$	(33	)	$	(358	)	$	4,297		$	—		$	3,906

Cash flows from investing activities
Capital expenditures	(4		)	—			(1,345		)	—			(1,349		)
Capital expenditures for discontinued operations	—			—			(42		)	—			(42		)
Proceeds from disposal of assets, net	—			—			60			—			60
Proceeds from insurance recoveries for loss of drilling unit	—			—			560			—			560
Investing activities with affiliates, net	310			1,357			(1,694		)	27			—
Other, net	—			(6		)	56			—			50
Net cash provided by (used in) investing activities	306			1,351			(2,405		)	27			(721		)

Cash flows from financing activities
Changes in short-term borrowings, net	—			(193		)	—			—			(193		)
Proceeds from debt	—			1,999			55			—			2,054
Repayments of debt	—			(2,245		)	(320		)	—			(2,565		)
Purchases of shares held in treasury	(240		)	—			—			—			(240		)
Financing activities with affiliates, net	—			1,384			(1,357		)	(27		)	—
Other, net	—			(14		)	(3		)	—			(17		)
Net cash provided by (used in) financing activities	(240		)	931			(1,625		)	(27		)	(961		)

Net increase in cash and cash equivalents	33			1,924			267			—			2,224
Cash and cash equivalents at beginning of period	5			117			1,008			—			1,130
Cash and cash equivalents at end of period	$	38		$	2,041		$	1,275		$	—		$	3,354

Quarterly Results (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2012

Quarterly Results (Unaudited)

Schedule of Quarterly Financial Data (Unaudited)

	Three months ended
	March 31,		June 30,			September 30,			December 31,
	(In millions, except per share data)
2012
Operating revenues	$	2,110	$	2,329		$	2,431		$	2,326
Operating income (loss) (a)	371		(142		)	811			541
Income (loss) from continuing operations	154		(303		)	533			432
Net income (loss) attributable to controlling interest (a) (b)	10		(304		)	(381		)	456
Per share earnings (loss) from continuing operations
Basic	$	0.42	$	(0.86	)	$	1.49		$	1.19
Diluted	$	0.42	$	(0.86	)	$	1.49		$	1.19
Weighted-average shares outstanding
Basic	350		353			359			359
Diluted	350		353			359			360

2011
Operating revenues	$	1,869	$	2,051		$	1,974		$	2,133
Operating income (loss) (c)	366		380			303			(5,811		)
Income (loss) from continuing operations	180		171			(19		)	(6,094		)
Net income (loss) attributable to controlling interest (c) (d)	319		124			(32		)	(6,165		)
Per share earnings (loss) from continuing operations
Basic	$	0.51	$	0.51		$	(0.09	)	$	(18.67	)
Diluted	$	0.51	$	0.50		$	(0.09	)	$	(18.67	)
Weighted-average shares outstanding
Basic	319		320			320			329
Diluted	320		320			320			329

Nature of Business (Details)				12 Months Ended
Nature of Business (Details)	Dec. 31, 2012 drillingunit	Dec. 31, 2012 Continuing operations drillingunit	Nov. 12, 2012 Discontinued operations drillingunit	Dec. 31, 2012 Discontinued operations Shelf Drilling International Holdings, Ltd	Dec. 31, 2012 Discontinued operations Shelf Drilling International Holdings, Ltd Minimum	Dec. 31, 2012 Discontinued operations Shelf Drilling International Holdings, Ltd Maximum
Number of mobile offshore drilling units		82
Number of High-Specification Floaters (in drilling units)		48
Number of Midwater Floaters (in drilling units)		25
Number of High-Specification Jackups (in drilling units)		9
Number of Standard Jackups (in drilling units)			25
Number of Standard Jackups sold (in drilling units)			37
Number of swamp barge sold (in drilling units)			1
Period for which Standard Jackups are agreed to be operated under operating agreements					9 months	27 months
Maximum period for which transition services to be provided following the completion of the sale transactions				18 months
Number of Ultra-Deepwater drillships under construction (in drilling units)	4	6
Number of High-Specification Jackups under construction (in drilling units)		3

Significant Accounting Policies (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Significant Accounting Policies
Equity in earnings of unconsolidated entities		$ 5	$ 8
Carrying amounts of investments in and advances to unconsolidated affiliates	1	1
Contract drilling intangible revenues
Contract drilling intangible revenues	42	45	98
Share-based compensation expense
Number of trading days considered for calculation of average stock price	30 days
Share-based compensation expense	97	95	102
Income tax benefit on share-based compensation expense	12	16	13
Capitalized interest
Capitalized interest costs on construction work in progress	54	39	89
Foreign currency
Net foreign currency exchange gains (losses)	(27)	(99)	1
Cash and cash equivalents
Maximum period within which restriction is expected to expire for classifying restricted cash and investment as current assets	1 year
Minimum period after which restriction is expected to expire for classifying restricted cash and investment as other assets	1 year
Restricted cash investments	857	934
Restricted cash investments classified in other current assets	195	182
Restricted cash investments classified in other assets	662	752
Accounts receivable
Allowance for doubtful accounts	20	28
Materials and supplies
Allowance for obsolescence on materials and supplies	66	73
Assets held for sale
Assets held for sale, included in current assets	179	26
Property and equipment
Property and equipment as a percentage of total assets	61.00%
Depreciation and Amortization	(1,123)	(1,109)	(1,009)
Earnings (loss) from continuing operations (in dollars per share)	$ 2.27	$ (18.14)	$ 5.66
Drilling rig units
Property and equipment
Number of rigs for which useful life was adjusted	3	2	5
Drilling rig units \| Service life
Property and equipment
Depreciation and Amortization	$ 27	$ 2	$ 23
Earnings (loss) from continuing operations (in dollars per share)	$ 0.08	$ 0.01	$ 0.07
Drilling rig units \| Maximum
Property and equipment
Estimated original useful life	35 years
Estimated useful life before adjustment	29 years	30 years	36 years
Estimated useful life after adjustment	35 years	38 years	39 years
Drilling rig units \| Minimum
Property and equipment
Estimated original useful life	18 years
Estimated useful life before adjustment	30 years	20 years	20 years
Estimated useful life after adjustment	38 years	23 years	25 years
Buildings and improvements \| Maximum
Property and equipment
Estimated original useful life	30 years
Buildings and improvements \| Minimum
Property and equipment
Estimated original useful life	10 years
Machinery and equipment \| Maximum
Property and equipment
Estimated original useful life	12 years
Machinery and equipment \| Minimum
Property and equipment
Estimated original useful life	4 years

Significant Accounting Policies (Details 2) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Dec. 31, 2012 item	Dec. 31, 2011	Dec. 31, 2010
Long-lived assets and definite-lived intangible assets
Minimum number of asset groups in which impairment is indicated for measurement of impairment			1
Loss on impairment of assets held for sale			$ (22)
Goodwill and other indefinite-lived intangible assets
Number of reporting units			2
Estimated loss on impairment of goodwill		5,200	118	5,200
Adjustment to original estimate of goodwill	118		118
Adjustment to original estimate of goodwill, per diluted share	$ 0.33		$ 0.33
Pension and other postretirement benefits
Recognition period of investment gains or losses related to asset valuation for determining net periodic benefit cost			5 years
Conditional amortization gains or losses as percentage of greater of plan assets or liabilities, minimum			10.00%
Number of critical fair value assumptions			2
Aggregate liability of pension and other postretirement benefit plan obligations		640	639	640
Net periodic benefit costs			149	88	91
Customer relationships
Long-lived assets and definite-lived intangible assets
Loss on impairment of assets held for sale			22
Loss on impairment of assets per diluted share			$ 0.06
Loss on impairment of assets held for sale net of tax			$ 17
Trade name intangible asset
Long-lived assets and definite-lived intangible assets
Loss on impairment of assets per diluted share			$ 0.07

Correction of Errors in Previously Reported Consolidated Financial Statements (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating revenues
Contract drilling revenues									$ 8,773	$ 7,407	$ 7,698
Other revenues									423	620	251
Total operating revenues	2,326	2,431	2,329	2,110	2,133	1,974	2,051	1,869	9,196	8,027	7,949
Costs and expenses
Operating and maintenance									6,106	6,179	4,219
Depreciation and amortization									1,123	1,109	1,009
General and administrative									282	288	246
Total costs and expenses									7,511	7,576	5,474
Loss on impairment									(140)	(5,201)
Gain (loss) on disposal of assets, net									36	(12)	255
Operating income (loss)	541	811	(142)	371	(5,811)	303	380	366	1,581	(4,762)	2,730
Other income (expense), net
Interest income									56	44	23
Interest expense, net of amounts capitalized									(723)	(621)	(567)
Other, net									(48)	(99)	(31)
Total other income (expense), net									(715)	(676)	(575)
Income (loss) from continuing operations before income tax expense									866	(5,438)	2,155
Income tax (benefit) expense									50	324	292
Income (loss) from continuing operations	432	533	(303)	154	(6,094)	(19)	171	180	816	(5,762)	1,863
Income (loss) from discontinued operations, net of tax									(1,027)	85	(894)
Net income (loss)									(211)	(5,677)	969
Net income (loss) attributable to noncontrolling interest									8	77	43
Net income (loss) attributable to controlling interest	456	(381)	(304)	10	(6,165)	(32)	124	319	(219)	(5,754)	926
Earnings (loss) per share-basic
Earnings (loss) from continuing operations (in dollars per share)									$ 2.27	$ (18.14)	$ 5.66
Earnings (loss) from discontinued operations (in dollars per share)									$ (2.89)	$ 0.26	$ (2.78)
Earnings (loss) per share (in dollars per share)	$ 1.19	$ 1.49	$ (0.86)	$ 0.42	$ (18.67)	$ (0.09)	$ 0.51	$ 0.51	$ (0.62)	$ (17.88)	$ 2.88
Earnings (loss) per share-diluted
Earnings (loss) from continuing operations (in dollars per share)									$ 2.27	$ (18.14)	$ 5.66
Earnings (loss) from discontinued operations (in dollars per share)									$ (2.89)	$ 0.26	$ (2.78)
Earnings (loss) per share (in dollars per share)	$ 1.19	$ 1.49	$ (0.86)	$ 0.42	$ (18.67)	$ (0.09)	$ 0.50	$ 0.51	$ (0.62)	$ (17.88)	$ 2.88
Previously reported
Operating revenues
Contract drilling revenues										7,413	7,698
Other revenues										620	251
Total operating revenues										8,033	7,949
Costs and expenses
Operating and maintenance										6,134	4,204
Depreciation and amortization										1,113	1,009
General and administrative										288	246
Total costs and expenses										7,535	5,459
Loss on impairment										(5,201)
Gain (loss) on disposal of assets, net										(12)	255
Operating income (loss)										(4,715)	2,745
Other income (expense), net
Interest income										44	23
Interest expense, net of amounts capitalized										(621)	(567)
Other, net										(99)	(31)
Total other income (expense), net										(676)	(575)
Income (loss) from continuing operations before income tax expense										(5,391)	2,170
Income tax (benefit) expense										340	288
Income (loss) from continuing operations										(5,731)	1,882
Income (loss) from discontinued operations, net of tax										99	(894)
Net income (loss)										(5,632)	988
Net income (loss) attributable to noncontrolling interest										93	27
Net income (loss) attributable to controlling interest										(5,725)	961
Earnings (loss) per share-basic
Earnings (loss) from continuing operations (in dollars per share)										$ (18.10)	$ 5.77
Earnings (loss) from discontinued operations (in dollars per share)										$ 0.31	$ (2.78)
Earnings (loss) per share (in dollars per share)										$ (17.79)	$ 2.99
Earnings (loss) per share-diluted
Earnings (loss) from continuing operations (in dollars per share)										$ (18.10)	$ 5.77
Earnings (loss) from discontinued operations (in dollars per share)										$ 0.31	$ (2.78)
Earnings (loss) per share (in dollars per share)										$ (17.79)	$ 2.99
Adjustments
Summary of adjustments for increases and (decreases) to net income (loss) from continuing operations and net income (loss) attributable to controlling interest
Adjustments related to Legal and other costs account										(67)
Adjustments related to Repair and maintenance costs account										11	(11)
Adjustments related to Other immaterial adjustments, net account										9	(4)
Operating revenues
Contract drilling revenues										(6)
Total operating revenues										(6)
Costs and expenses
Operating and maintenance										45	15
Depreciation and amortization										(4)
Total costs and expenses										41	15
Operating income (loss)										(47)	(15)
Other income (expense), net
Income (loss) from continuing operations before income tax expense										(47)	(15)
Income tax (benefit) expense										(16)	4
Income (loss) from continuing operations										(31)	(19)
Income (loss) from discontinued operations, net of tax										(14)
Net income (loss)										(45)	(19)
Net income (loss) attributable to noncontrolling interest										(16)	16
Net income (loss) attributable to controlling interest										$ (29)	$ (35)
Earnings (loss) per share-basic
Earnings (loss) from continuing operations (in dollars per share)										$ (0.04)	$ (0.11)
Earnings (loss) from discontinued operations (in dollars per share)										$ (0.05)
Earnings (loss) per share (in dollars per share)										$ (0.09)	$ (0.11)
Earnings (loss) per share-diluted
Earnings (loss) from continuing operations (in dollars per share)										$ (0.04)	$ (0.11)
Earnings (loss) from discontinued operations (in dollars per share)										$ (0.05)
Earnings (loss) per share (in dollars per share)										$ (0.09)	$ (0.11)

Correction of Errors in Previously Reported Consolidated Financial Statements (Details 2) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Assets
Cash and cash equivalents	$ 5,134	$ 4,017	$ 3,354	$ 1,130
Trade	1,940	2,049	1,653
Other	260	127	190
Materials and supplies, net	610	529	425
Deferred income taxes, net	142	142	115
Assets held for sale	179	26
Other current assets	382	646	472
Total current assets	8,647	7,536	6,209
Property and equipment	26,967	24,833	22,149
Property and equipment of consolidated variable interest entities	1,092	2,252	2,214
Less accumulated depreciation	7,179	6,297	5,244
Property and equipment, net	20,880	20,788	19,119
Goodwill	2,987	3,217	8,132
Other assets	1,741	3,491	3,354
Total assets	34,255	35,032	36,814
Liabilities and equity
Accounts payable	1,047	880	832
Accrued income taxes	116	86	109
Debt due within one year	1,339	1,942	1,917
Debt of consolidated variable interest entities due within one year	28	245	243
Other current liabilities	2,933	2,375	895
Total current liabilities	5,463	5,528	3,996
Long-term debt	10,929	10,756	8,354
Long-term debt of consolidated variable interest entities	163	593	707
Deferred income taxes, net	366	487	585
Other long-term liabilities	1,604	1,925	1,791
Total long-term liabilities	13,062	13,761	11,437
Commitments and contingencies
Redeemable noncontrolling interest		116	41
Shares	5,130	4,982	4,482
Additional paid-in capital	7,521	7,211	7,504
Treasury shares, at cost	(240)	(240)	(240)
Retained earnings	3,855	4,180	9,934
Accumulated other comprehensive loss	(521)	(496)	(332)
Total controlling interest shareholders' equity	15,745	15,637	21,348
Noncontrolling interest	(15)	(10)	(8)
Total equity	15,730	15,627	21,340	20,559
Total liabilities and equity	34,255	35,032	36,814
Previously reported
Assets
Cash and cash equivalents		4,017	3,394
Trade		2,049	1,653
Other		127	190
Materials and supplies, net		529	425
Deferred income taxes, net		142	115
Assets held for sale		26
Other current assets		719	418
Total current assets		7,609	6,195
Property and equipment		24,833	22,149
Property and equipment of consolidated variable interest entities		2,252	2,214
Less accumulated depreciation		6,301	5,244
Property and equipment, net		20,784	19,119
Goodwill		3,205	8,132
Other assets		3,490	3,365
Total assets		35,088	36,811
Liabilities and equity
Accounts payable		880	832
Accrued income taxes		86	109
Debt due within one year		1,942	1,917
Debt of consolidated variable interest entities due within one year		97	95
Other current liabilities		2,353	883
Total current liabilities		5,358	3,836
Long-term debt		10,756	8,354
Long-term debt of consolidated variable interest entities		741	855
Deferred income taxes, net		491	575
Other long-term liabilities		1,935	1,791
Total long-term liabilities		13,923	11,575
Commitments and contingencies
Redeemable noncontrolling interest		116	25
Shares		4,982	4,482
Additional paid-in capital		7,211	7,504
Treasury shares, at cost		(240)	(240)
Retained earnings		4,244	9,969
Accumulated other comprehensive loss		(496)	(332)
Total controlling interest shareholders' equity		15,701	21,383
Noncontrolling interest		(10)	(8)
Total equity		15,691	21,375
Total liabilities and equity		35,088	36,811
Adjustments
Assets
Cash and cash equivalents			(40)
Other current assets		(73)	54
Total current assets		(73)	14
Less accumulated depreciation		(4)
Property and equipment, net		4
Goodwill		12
Other assets		1	(11)
Total assets		(56)	3
Liabilities and equity
Debt of consolidated variable interest entities due within one year		148	148
Other current liabilities		22	12
Total current liabilities		170	160
Long-term debt of consolidated variable interest entities		(148)	(148)
Deferred income taxes, net		(4)	10
Other long-term liabilities		(10)
Total long-term liabilities		(162)	(138)
Commitments and contingencies
Redeemable noncontrolling interest			16
Retained earnings		(64)	(35)
Total controlling interest shareholders' equity		(64)	(35)
Total equity		(64)	(35)
Total liabilities and equity		$ (56)	$ 3

Business Combination (Details) (Aker Drilling)	0 Months Ended	1 Months Ended	12 Months Ended
Business Combination (Details) (Aker Drilling)	Oct. 03, 2011 USD ($)	Aug. 31, 2011 NOK	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Oct. 03, 2011 NOK	Aug. 14, 2011
Business Combination
Ownership interest to be acquired in business combination (as a percent)							41.00%
Percentage of shares for which cash offer has been launched		100.00%
Value per share at which shares offered under cash offer		26.50
Percentage of equity held by entity immediately before the acquisition date	99.00%
Aggregate amount paid	$ 1,400,000,000					7,900,000,000
Acquisition costs recognized in general and administrative expense				22,000,000
Purchase price allocated to assets and liabilities at estimated fair value
Current assets	323,000,000
Drilling rigs and other property and equipment	1,800,000,000
Other assets	757,000,000
Other liabilities	291,000,000
Long-term debt	1,600,000,000
Restricted cash investment	901,000,000
Goodwill	285,000,000
Number of months of acquiree's operating results included in financial statements				3 months
Contract drilling revenues associated with the operations of Aker Drilling included in operating revenues			380,000,000	100,000,000
Pro forma combined operating results
Operating revenues				8,339,000,000	8,280,000,000
Operating income (loss)				(4,616,000,000)	2,848,000,000
Income (loss) from continuing operations				$ (5,664,000,000)	$ 1,899,000,000
Per share earnings (loss) from continuing operations
Basic (in dollars per share)				$ (17.84)	$ 5.77
Diluted (in dollars per share)				$ (17.84)	$ 5.77

Variable Interest Entities (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 note	Dec. 31, 2011	Dec. 31, 2010 drillingunit	Feb. 29, 2012	May 29, 2012 TPDI	Dec. 31, 2011 TPDI	Oct. 18, 2007 TPDI	Dec. 31, 2012 ADDCL	Dec. 31, 2011 ADDCL	Dec. 31, 2012 TDSOI	Oct. 30, 2012 TDSOI
Carrying amounts associated with consolidated variable interest entities
Assets	$ 1,231	$ 2,492				$ 1,562		$ 954	$ 930	$ 277
Liabilities	311	1,007				673		296	334	15
Net carrying amount	920	1,485				889		658	596	262
Ownership interest held by minority interest (as a percent)				50.00%	50.00%						30.00%
Ownership interest in affiliate (as a percent)							50.00%			70.00%
Aggregate carrying amount of consolidated VIEs assets, pledged as security against outstanding debt of consolidated VIEs	805	2,200
Unconsolidated Variable interest entities
Number of notes receivable from sale of Midwater Floaters	2
Number of Midwater Floaters sold (in drilling units)			2
Stated interest rate on notes receivable received from sale of Midwater Floaters (as a percent)	9.00%
Stated interest rate on working capital loan (as a percent)	10.00%
Aggregate carrying amounts of notes receivable in connection with sale of Midwater Floaters	105	110
Aggregate exposure to loss on receivable instruments in connection with sale of Midwater Floaters		$ 29

Intangible Asset Impairments (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011
Impairment of goodwill and other indefinite Lived intangible assets
Estimated loss on impairment of goodwill		$ 5,200	$ 118	$ 5,200
Estimate of loss on impairment of goodwill per diluted share			$ 0.33	$ 16.15
Adjustment to original estimate of goodwill	118		118
Adjustment to original estimate of goodwill, per diluted share	$ 0.33		$ 0.33
Impairment of definite-lived intangible assets
Impairment loss on definite-lived intangible asset			(22)
Customer relationships
Impairment of definite-lived intangible assets
Impairment loss on definite-lived intangible asset			22
Impairment loss on finite-lived intangible asset, continuing operations			$ 17

- Definition

Loss recognized during the period that results from the write-down of goodwill after comparing the implied fair value of reporting unit goodwill with the carrying amount of that goodwill. Goodwill is assessed at least annually for impairment.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 43

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 141R

-Paragraph 72

-Subparagraph d

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=14024403&loc=d3e13854-109267

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 47

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 45

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6388280&loc=d3e13777-109266

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (e)

-URI http://asc.fasb.org/extlink&oid=14024403&loc=d3e13816-109267

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 20

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 9: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 142

-Paragraph 45

-Subparagraph e

-Clause 5

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Income Taxes (Details) (USD $)	12 Months Ended							12 Months Ended
Income Taxes (Details) (USD $)	Dec. 31, 2012 jurisdiction	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Minimum	Dec. 31, 2012 Maximum	Dec. 31, 2012 Norway Tax Assessments Prior to 2012 item employee subsidiary	Nov. 30, 2012 Norway Tax Assessments Prior to 2012	Dec. 31, 2012 Norway Tax Assessments 2012 subsidiary advisor	Dec. 31, 2012 2006 and 2007 federal income tax returns	Dec. 31, 2012 2008 and 2009 federal income tax returns
Components of provision (benefit) for income taxes
Current tax expense	$ 183,000,000	$ 386,000,000	$ 396,000,000
Deferred tax benefit	(133,000,000)	(62,000,000)	(104,000,000)
Income tax expense	50,000,000	324,000,000	292,000,000
Swiss holding company federal statutory rate (as a percent)	7.83%
Reconciliation of the differences between the income tax expense for the entity's continuing operations computed at the Swiss holding company statutory rate and the reported provision for income taxes
Income tax expense at the Swiss federal statutory rate	68,000,000	(426,000,000)	168,000,000
Taxes on earnings subject to rates different than the Swiss federal statutory rate	141,000,000	221,000,000	72,000,000
Taxes on impairment loss subject to rates different than the Swiss federal statutory rate	5,000,000	409,000,000
Taxes on asset sales subject to rates different than the Swiss federal statutory rate	(1,000,000)
Taxes on litigation matters subject to rates different than the Swiss federal statutory rate	59,000,000	78,000,000
Changes in unrecognized tax benefits, net	(179,000,000)	40,000,000	73,000,000
Change in valuation allowance	1,000,000	19,000,000	4,000,000
Benefit from foreign tax credits	(38,000,000)	(28,000,000)	(23,000,000)
Taxes on asset acquisition costs at rates lower than the Swiss federal statutory rate		8,000,000
Other, net	(6,000,000)	3,000,000	(2,000,000)
Income tax expense	50,000,000	324,000,000	292,000,000
Deferred tax assets
Drilling contract intangibles	1,000,000	2,000,000
Net operating loss carryforwards	380,000,000	331,000,000
Tax credit carryforwards	41,000,000	45,000,000
Accrued payroll expenses not currently deductible	95,000,000	79,000,000
Deferred income	86,000,000	65,000,000
Valuation allowance	(210,000,000)	(183,000,000)
Other	108,000,000	104,000,000
Total deferred tax assets	501,000,000	443,000,000
Deferred tax liabilities
Depreciation and amortization	(688,000,000)	(746,000,000)
Other	(37,000,000)	(42,000,000)
Total deferred tax liabilities	(725,000,000)	(788,000,000)
Net deferred tax liabilities	(224,000,000)	(345,000,000)
U.S. foreign tax credit carryforwards	41,000,000
Tax effect of Brazilian net operating losses	55,000,000	57,000,000
Norwegian NOLs acquired in connection with Aker Drilling acquisition			141,000,000
Deferred taxes
Valuation allowance for non-current deferred tax assets	210,000,000	183,000,000
Indefinitely reinvested earnings of subsidiaries	2,500,000,000
Estimated taxes on unremitted earnings of subsidiaries, low end of range	180,000,000
Estimated taxes on unremitted earnings of subsidiaries, high end of range	230,000,000
Reconciliation of unrecognized tax benefits, excluding interest and penalties
Balance, beginning of period	515,000,000	485,000,000	460,000,000
Additions for current year tax positions	58,000,000	45,000,000	46,000,000
Additions for prior year tax positions	25,000,000	29,000,000	9,000,000
Reductions for prior year tax positions	(24,000,000)		(11,000,000)
Settlements	(120,000,000)	(42,000,000)	(17,000,000)
Reductions related to statute of limitation expirations	(72,000,000)	(2,000,000)	(2,000,000)
Balance, end of period	382,000,000	515,000,000	485,000,000
Unrecognized tax benefits
Unrecognized tax benefits, excluding interest and penalties	382,000,000	515,000,000
Interest and penalties	199,000,000	256,000,000
Unrecognized tax benefits, including interest and penalties	581,000,000	771,000,000
Interest and penalties related to unrecognized tax benefits recognized as a component of income tax expense	56,000,000	20,000,000	35,000,000
Income Tax Examination
Range of tax returns are subject to examination				3 years	6 years
Number of jurisdictions with extensions beyond statute of limitations	2
Maximum number of years agreed to extensions beyond the statute of limitations	18 years
Additional tax, excluding interest and penalties payable on settlement with the U.S. tax authorities									11,000,000	36,000,000
Net adjustments of additional taxes, excluding interest and penalties, related to assessments on 2008 and 2009 U.S. federal income tax returns										363,000,000
Norway tax assessment due to migration of subsidiary, including interest						123,000,000	123,000,000
Norway tax assessment due to 2001 dividend payment, including interest						74,000,000
Norway tax assessment due to foreign exchange deductions and dividend withholding taxes, including interest						8,000,000
Guarantee amount for tax assessment related to the migration of subsidiary						125,000,000
Norway tax additional financial security, including interest and penalties						218,000,000
Percentage of penalties to be assessed by Norway tax authorities						60.00%
Number of appeals to tax assessments expected to be filed or filed						2
Number of subsidiaries against which notification of criminal charges are issued						2		2
Number of subsidiaries against which notification of criminal charges are extending								2
Number of employees of former external advisors indicted						2		2
Financial claim issued by the Norweigian authorities supplementing the criminal indictments								330,000,000
Brazil tax assessment penalty	73,000,000
Brazil tax assessment interest	147,000,000
Brazil tax assessment for income tax returns 2000 to 2004	$ 98,000,000
Percentage of penalties to be assessed by Brazil tax authorities	75.00%

Discontinued Operations (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended							9 Months Ended	12 Months Ended		12 Months Ended							1 Months Ended		12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Customer relationships	Dec. 31, 2012 Trade name intangible asset	Dec. 31, 2012 Sell of Standard Jackup and swamp barge market sectors	Dec. 31, 2010 Sell of Standard Jackup and swamp barge market sectors	Sep. 30, 2012 Shelf Drilling International Holdings, Ltd	Dec. 31, 2012 Shelf Drilling International Holdings, Ltd item drillingunit	Nov. 30, 2012 Shelf Drilling International Holdings, Ltd drillingunit	Dec. 31, 2012 Shelf Drilling International Holdings, Ltd Minimum	Dec. 31, 2012 Shelf Drilling International Holdings, Ltd Maximum	Dec. 31, 2012 Standard Jackups George H. Galloway, GSF Britannia, GSF Labrador and Transocean Mercury and swamp barge Searex IV	Dec. 31, 2011 Standard Jackups George H. Galloway, GSF Britannia, GSF Labrador and Transocean Mercury and swamp barge Searex IV	Dec. 31, 2011 High-Specification Jackup Trident 20	Dec. 31, 2012 Challenger Minerals	Dec. 31, 2011 Challenger Minerals	May 31, 2012 Challenger Minerals (North Sea)	Oct. 30, 2011 Challenger Minerals (North Sea)	Dec. 31, 2012 Challenger Minerals (North Sea)	Dec. 31, 2011 Challenger Minerals (North Sea)	Dec. 31, 2012 Challenger Minerals Inc. and Challenger Minerals (Ghana) Limited	Dec. 31, 2012 Challenger Minerals Inc.	Dec. 31, 2012 Challenger Minerals (Ghana) Limited	Dec. 31, 2012 GSF Adriatic II and GSF Rig 136	Dec. 31, 2011 George H. Galloway, GSF Britannia, GSF Labrador and Searex IV
Summarized results of discontinued operations
Operating revenues	$ 1,055	$ 1,171	$ 1,627
Operating and maintenance expense	(990)	(871)	(916)
Depreciation and amortization expense	(183)	(342)	(580)
Loss on impairment of assets in discontinued operations, net	(986)	(38)	(1,012)													(10)	(6)								(29)	(28)
Gain (loss) on disposal of assets in discontinued operations, net	82	183	2												169					9		9
Other income, net		18	8
Income (loss) from discontinued operations before income tax expense	(1,022)	121	(871)
Income tax expense	(5)	(36)	(23)
Income (loss) from discontinued operations, net of tax	(1,027)	85	(894)
Assets
Rigs and related equipment, net	104
Materials and supplies	71					8
Oil and gas properties, net		24
Other related assets	4	2
Assets held for sale	179	26
Materials and supplies		98
Other assets		21
Other current assets		119
Rig and related equipment, net		1,745
Intangible assets		70
Deferred costs		42
Other assets		1,857
Liabilities
Deferred revenue	32	17
Deferred income taxes, net		6
Other liabilities	3	14
Other current liabilities	35	37
Deferred revenue		8
Deferred taxes, net		32
Other long-term liabilities		40
Summarized results of Discontinued Operations
Goodwill allocated to disposal group						112
Aggregate carrying amounts of assets associated with disposal group						112
Letters of credit issued under committed and uncommitted credit lines									113	113
Term of letters of credit								3 years
Impairment costs relating to employees and contract labor									20
Impairment costs including costs for required reactivation and mobilizing certain drilling units									60
Number of reactive drilling unit									1
Legal and financial advisory costs									17
Expected transition services offering period									18 months
Period for which Standard Jackups are agreed to be operated under operating agreements											9 months	27 months
Number of private equity firms									3
Cumulative percentage of perpetual preference shares									10.00%
Escalating percentage of perpetual preference shares									2.00%
Maximum cumulative percentage of perpetual preference shares									14.00%
Embedded Derivatives									2
Proceeds from disposal of assets, net	191	14	60						568				201	185
Gain (loss) on disposal of assets, net	36	(12)	255						8				74	32							4
Gain (loss) on sale of assets, net of tax									5												14
Aggregate gains on sale of assets per diluted share									$ 0.01				$ 0.20	$ 0.10	$ 0.52					$ 0.02	$ 0.05	$ 0.02
Recognized losses on disposal of unrelated assets													9	1
Long live assets impairment loss						744	1,000
Long live assets impairment loss per diluted share from discontinued operations, net of tax						$ 2.08	$ 3.13
Number of Drilling Units Sold										38
Proceeds from disposal of discontinued operations non-cash									196
Proceeds from disposal of discontinued operations non-cash estimated fair value	194		134						194
Number of Standard Jackups (in drilling units)									25
Maximum financial support									125
Maximum additional financial support, excluding parent guarantees									65
Proceeds from disposal of discontinued operations, net	789	447													259			10	24				7	6
Goodwill impairment loss						112
Goodwill impairment loss per diluted share from discontinued operations, net of tax						$ 0.31
Loss on impairment, tax effect																										1
Impairment loss per diluted share from discontinued operations, net of tax																$ 0.02	$ 0.02								$ 0.08	$ 0.09
Loss on impairment of assets held for sale																11	10
Loss on impairment of assets per diluted share				$ 0.06	$ 0.07
Loss on impairment of assets held for sale net of tax				20	25
Impairment loss on indefinite-lived intangible asset				$ 31	$ 39

Earnings (Loss) Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Numerator for earnings (loss) per share, basic
Income (loss) from continuing operations attributable to controlling interest									$ 808	$ (5,839)	$ 1,820
Undistributed earnings allocable to participating securities											(10)
Income (loss) from continuing operations available to shareholders									808	(5,839)	1,810
Denominator for earnings (loss) per share, basic
Weighted-average shares outstanding	359	359	353	350	329	320	320	319	356	322	320
Weighted-average shares for per share calculation, basic	359	359	353	350	329	320	320	319	356	322	320
Per share earnings (loss) from continuing operations, basic									$ 2.27	$ (18.14)	$ 5.66
Numerator for earnings per share, diluted
Income (loss) from continuing operations attributable to controlling interest									808	(5,839)	1,820
Undistributed earnings allocable to participating securities											(10)
Income (loss) from continuing operations available to shareholders									$ 808	$ (5,839)	$ 1,810
Denominator for earnings per share, diluted
Weighted-average shares outstanding	359	359	353	350	329	320	320	319	356	322	320
Weighted-average shares for per share calculation, diluted	360	359	353	350	329	320	320	320	356	322	320
Per share earnings (loss) from continuing operations, diluted									$ 2.27	$ (18.14)	$ 5.66
1.625% Series A Convertible Senior Notes due December 2037
Anti-dilutive securities
Interest rate on convertible debt not having effect on earning per share calculation (as a percent)	1.625%								1.625%
1.50% Series B Convertible Senior Notes due December 2037
Anti-dilutive securities
Interest rate on convertible debt not having effect on earning per share calculation (as a percent)	1.50%								1.50%
1.50% Series C Convertible Senior Notes due December 2037
Anti-dilutive securities
Interest rate on convertible debt not having effect on earning per share calculation (as a percent)	1.50%								1.50%
Share-based awards
Anti-dilutive securities
Share-based awards excluded from earnings per share calculation									2.4	2.4	2.2

Other Comprehensive Income (Loss) (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Allocation of other comprehensive income (loss)
Unrecognized components of net periodic benefit costs	$ (52)	$ (204)	$ (8)
Unrecognized gain (loss) on derivative instruments	3	(13)	(29)
Unrecognized loss on marketable securities		(13)
Recognized components of net periodic benefit costs	47	25	16
Recognized (gain) loss on derivative instruments	(1)	11	12
Recognized loss on marketable security	2	13
Other comprehensive income (loss) before income taxes	(1)	(181)	(9)
Income taxes related to other comprehensive income (loss)	(7)	13	(9)
Other comprehensive income (loss), net of income taxes	(8)	(168)	(18)
Controlling interest
Allocation of other comprehensive income (loss)
Unrecognized components of net periodic benefit costs	(52)	(204)	(8)
Unrecognized gain (loss) on derivative instruments	6	3	(10)
Unrecognized loss on marketable securities		(13)
Recognized components of net periodic benefit costs	47	25	16
Recognized (gain) loss on derivative instruments	(4)	(1)	14
Recognized loss on marketable security	2	13
Other comprehensive income (loss) before income taxes	(1)	(177)	12
Income taxes related to other comprehensive income (loss)	(7)	13	(9)
Other comprehensive income (loss), net of income taxes	(8)	(164)	3
Non-controlling interest and Redeemable non-controlling interest
Allocation of other comprehensive income (loss)
Unrecognized gain (loss) on derivative instruments	(3)	(16)	(19)
Recognized (gain) loss on derivative instruments	3	12	(2)
Other comprehensive income (loss) before income taxes		(4)	(21)
Other comprehensive income (loss), net of income taxes		$ (4)	$ (21)

Drilling Fleet (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended	12 Months Ended
	Mar. 31, 2010	Dec. 31, 2012 drillingunit	Dec. 31, 2011	Dec. 31, 2010
Capital expenditures and other capital additions, including capitalized interest costs
Construction work in progress, at beginning of period		$ 1,360	$ 1,450	$ 3,657
Total capital expenditures		1,303	974	1,349
Acquisition of construction work in progress			272
Changes in accrued capital expenditures		61	(2)	(57)
Construction work in progress, at end of period		1,972	1,360	1,450
Number of Ultra-Deepwater drillships under construction		4
Number of Harsh Environment, Ultra-Deepwater semisubmersibles acquired (in drilling units)		2
Cash payment to acquire GSF Explorer, an asset formerly held under capital lease	15
Ultra-Deepwater Floater TBN1
Capital expenditures and other capital additions, including capitalized interest costs
Total capital expenditures		139
Ultra-Deepwater Floater TBN2
Capital expenditures and other capital additions, including capitalized interest costs
Total capital expenditures		128
Ultra-Deepwater Floater TBN3
Capital expenditures and other capital additions, including capitalized interest costs
Total capital expenditures		76
Ultra-Deepwater Floater TBN4
Capital expenditures and other capital additions, including capitalized interest costs
Total capital expenditures		76
Transocean Ao Thai
Capital expenditures and other capital additions, including capitalized interest costs
Total capital expenditures		72	80
Transocean Siam Driller
Capital expenditures and other capital additions, including capitalized interest costs
Total capital expenditures		39	113	9
Transocean Andaman
Capital expenditures and other capital additions, including capitalized interest costs
Total capital expenditures		38	113	9
Transocean Honor
Capital expenditures and other capital additions, including capitalized interest costs
Total capital expenditures		35	129	98
Property and equipment placed into service		(262)
Ownership interest in affiliate (as a percent)		70.00%
Costs as a percentage of total expenditures incurred since inception		100.00%
Deepwater Asgard and Deepwater Invictus
Capital expenditures and other capital additions, including capitalized interest costs
Acquisition of construction work in progress			272
Number of Ultra-Deepwater Floaters under construction which are expected to commence operations in the second quarter of 2014		2
Deepwater Champion
Capital expenditures and other capital additions, including capitalized interest costs
Total capital expenditures			76	249
Property and equipment placed into service			(881)
Discoverer India
Capital expenditures and other capital additions, including capitalized interest costs
Total capital expenditures				262
Property and equipment placed into service				(835)
Discoverer Luanda
Capital expenditures and other capital additions, including capitalized interest costs
Total capital expenditures				212
Property and equipment placed into service				(783)
Ownership interest in affiliate (as a percent)		65.00%
Costs as a percentage of total expenditures incurred since inception		100.00%
Dhirubhai Deepwater KG2
Capital expenditures and other capital additions, including capitalized interest costs
Total capital expenditures				45
Property and equipment placed into service				(707)
Discoverer Inspiration
Capital expenditures and other capital additions, including capitalized interest costs
Total capital expenditures				33
Property and equipment placed into service				(781)
Other construction projects and capital additions
Capital expenditures and other capital additions, including capitalized interest costs
Total capital expenditures		614	456	432
Other property and equipment
Capital expenditures and other capital additions, including capitalized interest costs
Property and equipment placed into service		(490)	(453)	(393)
Transocean Siam Driller, Transocean Andaman and Transocean Ao Thai
Capital expenditures and other capital additions, including capitalized interest costs
Number of high-specification jackups purchased and under construction		3
Deepwater Asgard
Capital expenditures and other capital additions, including capitalized interest costs
Total capital expenditures		46	4
Deepwater Invictus
Capital expenditures and other capital additions, including capitalized interest costs
Total capital expenditures		$ 40	$ 3

Drilling Fleet (Details 2) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Dispositions
Net cash proceeds from sale of assets	$ 191	$ 14	$ 60
Gain (loss) on the sale of assets	36	(12)	255
Loss of drilling unit
Proceeds from insurance recoveries			560
Gain on loss of drilling unit			267
Gain loss on loss of drilling unit per diluted share			$ 0.83
Sell of Standard Jackup, swamp barge market sectors, Deepwater Floaters Discoverer 534 and Jim Cunningham
Dispositions
Net cash proceeds from sale of assets	178
Gain (loss) on the sale of assets	51
Gain (loss) on the sale of assets, net of tax	48
Gain (loss) on the sale of assets per diluted share	$ 0.13
Sale of Other Assets
Dispositions
Gain (loss) on the sale of assets	15	12
Midwater Floaters
Dispositions
Net cash proceeds from sale of assets			38
Gain (loss) on the sale of assets			5
Number of notes receivable provided as Non-Cash proceeds from sale of assets	2
Aggregate amount of notes receivable			165
Gain (loss) on the sale of assets	$ 15
Gain (loss) on the sale of assets per diluted share	$ 0.05

Goodwill and Other Intangible Assets (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011
Accumulated impairment
Impairment associated with continuing operations	$ (5,200)	$ (118)	$ (5,200)
Net carrying amount
Net carrying amount at the beginning of the period		3,217	8,132
Impairment associated with continuing operations	(5,200)	(118)	(5,200)
Net carrying amount at the end of the period	3,217	2,987	3,217
Contract drilling services
Goodwill
Gross carrying amount at the beginning of the period		10,911	10,626
Business combination			285
Reclassified balance associated with discontinued operations		(112)
Gross carrying amount at the end of the period	10,911	10,799	10,911
Accumulated impairment
Accumulated impairment at the beginning of the period		(7,694)	(2,494)
Impairment associated with continuing operations		(118)	(5,200)
Accumulated impairment at the end of the period	(7,694)	(7,812)	(7,694)
Net carrying amount
Net carrying amount at the beginning of the period		3,217	8,132
Impairment associated with continuing operations		(118)	(5,200)
Reclassified balance associated with discontinued operations		(112)
Business combination			285
Net carrying amount at the end of the period	3,217	2,987	3,217
Drilling management services
Goodwill
Gross carrying amount at the end of the period	$ 176	$ 176	$ 176

Goodwill and Other Intangible Assets (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2010
Indefinite-lived intangible asset, gross, excluding goodwill
Reclassified balance associated with discontinued operations	$ (270)
Indefinite-lived intangible asset, net, excluding goodwill
Reclassified balance associated with discontinued operations	(31)
ADTI trade name \| Drilling management services
Indefinite-lived intangible asset, gross, excluding goodwill
Gross carrying amount at the beginning of the period	76	76
Reclassified balance associated with discontinued operations	(76)
Gross carrying amount at the end of the period		76
Indefinite-lived intangible asset, net carrying amount
Accumulated impairment at the beginning of the period	(37)	(37)
Reclassified balance associated with discontinued operations	37
Accumulated impairment at the end of the period		(37)
Indefinite-lived intangible asset, net, excluding goodwill
Net carrying amount at the beginning of the period	39	39
Reclassified balance associated with discontinued operations	(39)
Net carrying amount at the end of the period		$ 39

Goodwill and Other Intangible Assets (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Change in gross carrying amounts of definite-lived intangible assets
Gross carrying amount at the beginning of the period	$ 339	$ 339
Reclassified balance associated with discontinued operations	(270)
Gross carrying amount at the end of the period	69	339
Changes in accumulated amortization and impairment of definite-lived intangible liabilities of definite-lived intangible liabilities
Amortization	(1)	(11)
Impairment associated with continuing operations	(22)
Reclassified balance associated with discontinued operations	239
Changes in net carrying amount of definite-lived intangible liabilities
Net carrying amount at the beginning of the period	54	65
Amortization	(1)	(11)
Impairment associated with continuing operations	(22)
Reclassified balance associated with discontinued operations	(31)
Net carrying amount at the end of the period		54
Accumulated amortization and impairment at the beginning of the period	(285)	(274)
Accumulated amortization and impairment at the end of the period	(69)	(285)
Drilling contract intangible assets
Change in gross carrying amounts of definite-lived intangible assets
Gross carrying amount at the beginning of the period	191	191
Reclassified balance associated with discontinued operations	(182)
Gross carrying amount at the end of the period	9	191
Changes in accumulated amortization and impairment of definite-lived intangible liabilities of definite-lived intangible liabilities
Amortization		(6)
Reclassified balance associated with discontinued operations	(182)
Changes in net carrying amount of definite-lived intangible liabilities
Net carrying amount at the beginning of the period		6
Amortization		(6)
Accumulated amortization and impairment at the beginning of the period	(191)	(185)
Accumulated amortization and impairment at the end of the period	(9)	(191)
Customer relationships
Change in gross carrying amounts of definite-lived intangible assets
Gross carrying amount at the beginning of the period	148	148
Reclassified balance associated with discontinued operations	(88)
Gross carrying amount at the end of the period	60	148
Changes in accumulated amortization and impairment of definite-lived intangible liabilities of definite-lived intangible liabilities
Amortization	(1)	(5)
Impairment associated with continuing operations	(22)
Reclassified balance associated with discontinued operations	57
Changes in net carrying amount of definite-lived intangible liabilities
Net carrying amount at the beginning of the period	54	59
Amortization	(1)	(5)
Impairment associated with continuing operations	(22)
Reclassified balance associated with discontinued operations	(31)
Net carrying amount at the end of the period		54
Accumulated amortization and impairment at the beginning of the period	(94)	(89)
Accumulated amortization and impairment at the end of the period	(60)	(94)
Drilling contract intangible liabilities
Change in gross carrying amounts of definite-lived intangible assets
Reclassified balance associated with discontinued operations	(84)
Changes in accumulated amortization and impairment of definite-lived intangible liabilities of definite-lived intangible liabilities
Accumulated amortization and impairment at the beginning of the period	(1,393)	(1,342)
Amortization	(42)	(51)
Reclassified balance associated with discontinued operations	(84)
Accumulated amortization and impairment at the end of the period	(1,351)	(1,393)
Changes in net carrying amount of definite-lived intangible liabilities
Gross carrying amount at the beginning of the period	1,494	1,494
Gross carrying amount at the end of the period	1,410	1,494
Amortization	(42)	(51)
Net carrying amount at the beginning of the year	101	152
Net carrying amount at the end of the year	$ 59	$ 101

Goodwill and Other Intangible Assets (Details 4) (Drilling contract intangible liabilities, USD $) In Millions, unless otherwise specified	Dec. 31, 2012
Drilling contract intangible liabilities
Future amortization of our intangible liabilities
2013	$ 24
2014	15
2015	14
2016	6
Total intangible liabilities	$ 59

Debt (Details)	1 Months Ended	12 Months Ended														12 Months Ended					12 Months Ended				12 Months Ended				12 Months Ended		1 Months Ended	12 Months Ended			12 Months Ended										12 Months Ended			12 Months Ended		1 Months Ended	12 Months Ended							1 Months Ended	12 Months Ended				12 Months Ended	1 Months Ended	12 Months Ended		1 Months Ended	12 Months Ended			12 Months Ended						12 Months Ended		12 Months Ended								12 Months Ended																																															12 Months Ended			12 Months Ended								12 Months Ended										12 Months Ended					12 Months Ended		12 Months Ended				12 Months Ended
Debt (Details)	May 31, 2012 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2012 NOK	Dec. 31, 2011 USD ($)	Dec. 31, 2012 Dhirubhai Deepwater KG1 and Dhirubhai Deepwater KG2 USD ($)	Dec. 31, 2011 Dhirubhai Deepwater KG1 and Dhirubhai Deepwater KG2 USD ($)	Dec. 31, 2012 Ultra Deepwater Floater Discoverer Luanda USD ($)	Dec. 31, 2011 Ultra Deepwater Floater Discoverer Luanda USD ($)	Dec. 31, 2012 5% Notes due February 2013 USD ($)	Dec. 31, 2011 5% Notes due February 2013 USD ($)	Dec. 31, 2012 5.25% Senior Notes due March 2013 USD ($)	Dec. 31, 2011 5.25% Senior Notes due March 2013 USD ($)	Dec. 31, 2012 TPDI Credit Facilities due March 2015 USD ($)	Dec. 31, 2011 TPDI Credit Facilities due March 2015 USD ($)	Dec. 31, 2012 4.95% Senior Notes due November 2015 USD ($)	Dec. 31, 2011 4.95% Senior Notes due November 2015 USD ($)	Sep. 30, 2010 4.95% Senior Notes due November 2015 USD ($)	Dec. 31, 2011 Aker Revolving Credit and Term Loan Facility due December 2015 USD ($)	Feb. 21, 2011 Aker Revolving Credit Facility due December 2015 USD ($)	Dec. 31, 2012 Aker Term Loan Facility due December 2015 USD ($)	Feb. 21, 2011 Aker Term Loan Facility due December 2015 USD ($)	Dec. 31, 2012 Callable Bonds due February 2016 USD ($)	Dec. 31, 2011 Callable Bonds due February 2016 USD ($)	Dec. 31, 2012 FRN Callable Bonds USD ($)	Dec. 31, 2012 FRN Callable Bonds NOK	Dec. 31, 2012 11% Callable Bonds USD ($)	Dec. 31, 2012 11% Callable Bonds NOK	Dec. 31, 2012 5.05% Senior Notes due December 2016 USD ($)	Dec. 31, 2011 5.05% Senior Notes due December 2016 USD ($)	Sep. 30, 2012 2.5% Senior Notes due October 2017 USD ($)	Dec. 31, 2012 2.5% Senior Notes due October 2017 USD ($)	Dec. 31, 2012 ADDCL Credit Facilities due December 2017 USD ($)	Dec. 31, 2011 ADDCL Credit Facilities due December 2017 USD ($)	Dec. 31, 2012 Eksportfinans Loans due January 2018 USD ($)	Dec. 31, 2011 Eksportfinans Loans due January 2018 USD ($)	Dec. 31, 2012 Eksportfinans Loan A USD ($)	Dec. 31, 2012 Eksportfinans Loan B USD ($)	Dec. 31, 2012 6.00% Senior Notes due March 2018 USD ($)	Dec. 31, 2011 6.00% Senior Notes due March 2018 USD ($)	Dec. 31, 2012 7.375% Senior Notes due April 2018 USD ($)	Dec. 31, 2011 7.375% Senior Notes due April 2018 USD ($)	Mar. 31, 2002 7.375% Senior Notes due April 2018 USD ($)	Dec. 31, 2011 TPDI Notes due October 2019 USD ($)	Dec. 31, 2012 6.50% Senior Notes due November 2020 USD ($)	Dec. 31, 2011 6.50% Senior Notes due November 2020 USD ($)	Sep. 30, 2010 6.50% Senior Notes due November 2020 USD ($)	Dec. 31, 2012 6.375% Senior Notes due December 2021 USD ($)	Dec. 31, 2011 6.375% Senior Notes due December 2021 USD ($)	Sep. 30, 2012 3.8% Senior Notes due October 2022 USD ($)	Dec. 31, 2012 3.8% Senior Notes due October 2022 USD ($)	Dec. 31, 2012 7.45% Notes due April 2027 USD ($)	Dec. 31, 2011 7.45% Notes due April 2027 USD ($)	Dec. 31, 2012 8% Debentures due April 2027 USD ($)	Dec. 31, 2011 8% Debentures due April 2027 USD ($)	Dec. 31, 2012 7% Notes due June 2028 USD ($)	Dec. 31, 2011 7% Notes due June 2028 USD ($)	Aug. 31, 2009 Capital lease contract due August 2029 USD ($)	Dec. 31, 2012 Capital lease contract due August 2029 USD ($)	Dec. 31, 2011 Capital lease contract due August 2029 USD ($)	Dec. 31, 2012 7.5% Notes due April 2031 USD ($)	Dec. 31, 2011 7.5% Notes due April 2031 USD ($)	Dec. 31, 2012 1.625% Series A, 1.50% Series B and 1.50% Series C Convertible Senior Notes D	Jan. 31, 2011 1.625% Series A Convertible Senior Notes due December 2037 USD ($)	Dec. 31, 2012 1.625% Series A Convertible Senior Notes due December 2037 USD ($)	Dec. 31, 2007 1.625% Series A Convertible Senior Notes due December 2037 USD ($)	Feb. 29, 2012 1.50% Series B Convertible Senior Notes due December 2037 USD ($)	Dec. 31, 2012 1.50% Series B Convertible Senior Notes due December 2037 USD ($)	Dec. 31, 2011 1.50% Series B Convertible Senior Notes due December 2037 USD ($)	Dec. 31, 2007 1.50% Series B Convertible Senior Notes due December 2037 USD ($)	Dec. 31, 2012 1.50% Series C Convertible Senior Notes due December 2037 USD ($)	Dec. 31, 2010 1.50% Series C Convertible Senior Notes due December 2037 USD ($)	Dec. 31, 2011 1.50% Series C Convertible Senior Notes due December 2037 USD ($)	Dec. 31, 2007 1.50% Series C Convertible Senior Notes due December 2037 USD ($)	Dec. 31, 2012 6.80% Senior Notes due March 2038 USD ($)	Dec. 31, 2011 6.80% Senior Notes due March 2038 USD ($)	Dec. 31, 2012 7.35% Senior Notes due December 2041 USD ($)	Dec. 31, 2011 7.35% Senior Notes due December 2041 USD ($)	Dec. 31, 2012 Five Year Revolving Credit Facility USD ($)	Dec. 31, 2012 Five Year Revolving Credit Facility Minimum Facility Fee	Dec. 31, 2012 Five Year Revolving Credit Facility Maximum Facility Fee	Dec. 31, 2012 Five Year Revolving Credit Facility Adjusted LIBOR	Dec. 31, 2012 Five Year Revolving Credit Facility Base Rate	Dec. 31, 2012 Three Year Secured Revolving Credit Facility USD ($)	Dec. 31, 2012 Three Year Secured Revolving Credit Facility Deepwater Champion, Discoverer Americas and Discoverer Inspiration USD ($)	Dec. 31, 2011 Three Year Secured Revolving Credit Facility Deepwater Champion, Discoverer Americas and Discoverer Inspiration USD ($)	Dec. 31, 2012 Three Year Secured Revolving Credit Facility Minimum Facility Fee	Dec. 31, 2012 Three Year Secured Revolving Credit Facility Maximum Facility Fee	Dec. 31, 2012 Three Year Secured Revolving Credit Facility Adjusted LIBOR	Dec. 31, 2012 Three Year Secured Revolving Credit Facility Base Rate	Dec. 31, 2012 Transocean Ltd. and Subsidiaries USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries USD ($)	Dec. 31, 2012 Transocean Ltd. and Subsidiaries 5% Notes due February 2013 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 5% Notes due February 2013 USD ($)	Dec. 31, 2012 Transocean Ltd. and Subsidiaries 5.25% Senior Notes due March 2013 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 5.25% Senior Notes due March 2013 USD ($)	Dec. 31, 2012 Transocean Ltd. and Subsidiaries TPDI Credit Facilities due March 2015 USD ($)	Dec. 31, 2012 Transocean Ltd. and Subsidiaries 4.95% Senior Notes due November 2015 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 4.95% Senior Notes due November 2015 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries Aker Revolving Credit and Term Loan Facility due December 2015 USD ($)	Dec. 31, 2012 Transocean Ltd. and Subsidiaries Callable Bonds due February 2016 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries Callable Bonds due February 2016 USD ($)	Dec. 31, 2012 Transocean Ltd. and Subsidiaries 5.05% Senior Notes due December 2016 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 5.05% Senior Notes due December 2016 USD ($)	Dec. 31, 2012 Transocean Ltd. and Subsidiaries 2.5% Senior Notes due October 2017 USD ($)	Dec. 31, 2012 Transocean Ltd. and Subsidiaries Eksportfinans Loans due January 2018 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries Eksportfinans Loans due January 2018 USD ($)	Dec. 31, 2012 Transocean Ltd. and Subsidiaries 6.00% Senior Notes due March 2018 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 6.00% Senior Notes due March 2018 USD ($)	Dec. 31, 2012 Transocean Ltd. and Subsidiaries 7.375% Senior Notes due April 2018 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 7.375% Senior Notes due April 2018 USD ($)	Dec. 31, 2012 Transocean Ltd. and Subsidiaries 6.50% Senior Notes due November 2020 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 6.50% Senior Notes due November 2020 USD ($)	Dec. 31, 2012 Transocean Ltd. and Subsidiaries 6.375% Senior Notes due December 2021 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 6.375% Senior Notes due December 2021 USD ($)	Dec. 31, 2012 Transocean Ltd. and Subsidiaries 3.8% Senior Notes due October 2022 USD ($)	Dec. 31, 2012 Transocean Ltd. and Subsidiaries 7.45% Notes due April 2027 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 7.45% Notes due April 2027 USD ($)	Dec. 31, 2012 Transocean Ltd. and Subsidiaries 8% Debentures due April 2027 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 8% Debentures due April 2027 USD ($)	Dec. 31, 2012 Transocean Ltd. and Subsidiaries 7% Notes due June 2028 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 7% Notes due June 2028 USD ($)	Dec. 31, 2012 Transocean Ltd. and Subsidiaries Capital lease contract due August 2029 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries Capital lease contract due August 2029 USD ($)	Dec. 31, 2012 Transocean Ltd. and Subsidiaries 7.5% Notes due April 2031 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 7.5% Notes due April 2031 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 1.50% Series B Convertible Senior Notes due December 2037 USD ($)	Dec. 31, 2012 Transocean Ltd. and Subsidiaries 1.50% Series C Convertible Senior Notes due December 2037 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 1.50% Series C Convertible Senior Notes due December 2037 USD ($)	Dec. 31, 2012 Transocean Ltd. and Subsidiaries 6.80% Senior Notes due March 2038 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 6.80% Senior Notes due March 2038 USD ($)	Dec. 31, 2012 Transocean Ltd. and Subsidiaries 7.35% Senior Notes due December 2041 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 7.35% Senior Notes due December 2041 USD ($)	Dec. 31, 2012 Transocean Inc.	Dec. 31, 2012 Transocean Inc. 5.25% Senior Notes due March 2013 USD ($)	Dec. 31, 2007 Transocean Inc. 5.25% Senior Notes due March 2013 USD ($)	Dec. 31, 2012 Transocean Inc. 6.00% Senior Notes due March 2018 USD ($)	Dec. 31, 2007 Transocean Inc. 6.00% Senior Notes due March 2018 USD ($)	Dec. 31, 2012 Transocean Inc. 7.45% Notes due April 2027 USD ($)	Apr. 30, 1997 Transocean Inc. 7.45% Notes due April 2027 USD ($)	Dec. 31, 2012 Transocean Inc. 8% Debentures due April 2027 USD ($)	Apr. 30, 1997 Transocean Inc. 8% Debentures due April 2027 USD ($)	Dec. 31, 2012 Transocean Inc. 7.5% Notes due April 2031 USD ($)	Apr. 30, 2001 Transocean Inc. 7.5% Notes due April 2031 USD ($)	Dec. 31, 2012 Transocean Inc. 6.80% Senior Notes due March 2038 USD ($)	Dec. 31, 2007 Transocean Inc. 6.80% Senior Notes due March 2038 USD ($)	Dec. 31, 2012 Consolidated variable interest entities USD ($)	Dec. 31, 2011 Consolidated variable interest entities USD ($)	Dec. 31, 2011 Consolidated variable interest entities TPDI Credit Facilities due March 2015 USD ($)	Dec. 31, 2012 Consolidated variable interest entities ADDCL Credit Facilities due December 2017 USD ($)	Dec. 31, 2011 Consolidated variable interest entities ADDCL Credit Facilities due December 2017 USD ($)	Dec. 31, 2011 Consolidated variable interest entities TPDI Notes due October 2019 USD ($)	Dec. 31, 2012 TPDI TPDI Credit Facilities due March 2015 USD ($)	Dec. 31, 2011 TPDI TPDI Credit Facilities due March 2015 USD ($)	Dec. 31, 2012 TPDI TPDI Credit Facilities Senior Term Loan Due March 2015 USD ($)	Dec. 31, 2012 TPDI TPDI Credit Facilities Junior Term Loan Due March 2015 USD ($)	Dec. 31, 2012 TPDI TPDI Credit Facilities Revolving Credit Facility Due March 2015 USD ($)	Dec. 31, 2012 TPDI Uncommitted Credit Facility Established by Subsidiary USD ($)	Dec. 31, 2011 TPDI Uncommitted Credit Facility Established by Subsidiary USD ($)	Dec. 31, 2012 ADDCL ADDCL Credit Facilities Tranche A Due December 2017 USD ($)	Dec. 31, 2012 ADDCL ADDCL Credit Facilities Tranche C Due December 2017 USD ($)	Dec. 31, 2012 ADDCL ADDCL Secondary Loan Facility Due December 2015 USD ($)	Dec. 31, 2011 ADDCL ADDCL Secondary Loan Facility Due December 2015 USD ($)	Dec. 31, 2012 ADDCL ADDCL Secondary Loan Facility Due December 2015 Minimum Facility Fee	Dec. 31, 2012 ADDCL ADDCL Secondary Loan Facility Due December 2015 Maximum Facility Fee	Dec. 31, 2012 Wholly-owned subsidiaries 5% Notes due February 2013 USD ($) subsidiary	Dec. 31, 2012 Wholly-owned subsidiaries 7% Notes due June 2028 USD ($) subsidiary
Long-term debt by current and noncurrent
Total debt		$ 12,459,000,000			$ 13,536,000,000					$ 250,000,000	$ 253,000,000	$ 502,000,000	$ 507,000,000	$ 403,000,000	$ 473,000,000	$ 1,118,000,000	$ 1,120,000,000		$ 594,000,000				$ 282,000,000	$ 267,000,000					$ 999,000,000	$ 999,000,000		$ 748,000,000	$ 191,000,000	$ 217,000,000	$ 797,000,000	$ 884,000,000			$ 998,000,000	$ 998,000,000	$ 247,000,000	$ 247,000,000		$ 148,000,000	$ 899,000,000	$ 899,000,000		$ 1,199,000,000	$ 1,199,000,000		$ 745,000,000	$ 97,000,000	$ 97,000,000	$ 57,000,000	$ 57,000,000	$ 311,000,000	$ 311,000,000		$ 657,000,000	$ 676,000,000	$ 598,000,000	$ 598,000,000							$ 30,000,000		$ 62,000,000		$ 1,663,000,000		$ 999,000,000	$ 999,000,000	$ 300,000,000	$ 300,000,000													$ 12,268,000,000	$ 12,698,000,000	$ 250,000,000	$ 253,000,000	$ 502,000,000	$ 507,000,000	$ 403,000,000	$ 1,118,000,000	$ 1,120,000,000	$ 594,000,000	$ 282,000,000	$ 267,000,000	$ 999,000,000	$ 999,000,000	$ 748,000,000	$ 797,000,000	$ 884,000,000	$ 998,000,000	$ 998,000,000	$ 247,000,000	$ 247,000,000	$ 899,000,000	$ 899,000,000	$ 1,199,000,000	$ 1,199,000,000	$ 745,000,000	$ 97,000,000	$ 97,000,000	$ 57,000,000	$ 57,000,000	$ 311,000,000	$ 311,000,000	$ 657,000,000	$ 676,000,000	$ 598,000,000	$ 598,000,000	$ 30,000,000	$ 62,000,000	$ 1,663,000,000	$ 999,000,000	$ 999,000,000	$ 300,000,000	$ 300,000,000														$ 191,000,000	$ 838,000,000	$ 473,000,000	$ 191,000,000	$ 217,000,000	$ 148,000,000
Debt due within one year		1,367,000,000			2,187,000,000					250,000,000		502,000,000		70,000,000	70,000,000				90,000,000														28,000,000	27,000,000	153,000,000	142,000,000								148,000,000															20,000,000	17,000,000									30,000,000		62,000,000		1,663,000,000																		1,339,000,000	1,942,000,000	250,000,000		502,000,000		70,000,000			90,000,000	282,000,000					153,000,000	142,000,000																20,000,000	17,000,000			30,000,000	62,000,000	1,663,000,000																		28,000,000	245,000,000	70,000,000	28,000,000	27,000,000	148,000,000
Long-term debt		11,092,000,000			11,349,000,000																																																																																						10,929,000,000	10,756,000,000																																																							163,000,000	593,000,000
Debt instrument interest rate stated percentage										5.00%		5.25%				4.95%									11.00%	11.00%	11.00%	11.00%	5.05%			2.50%			4.15%				6.00%		7.375%				6.50%			6.375%			3.80%	7.45%		8.00%		7.00%					7.50%				1.625%			1.50%			1.50%				6.80%		7.35%
Percentage ownership interest in Transocean Inc. by Transocean Ltd.																																																																																																																																						100.00%
Scheduled monthly payments under capital lease obligation																																																											6,000,000
Purchase obligation to acquire asset under capital lease																																																											1
Percentage of principal amount that the holder of the note may require the entity to repurchase the debt instrument upon the occurrence of a fundamental change																																																															100.00%
Credit facility term																																																																															5 years					3 years
Borrowing capacity, maximum																				500,000,000																																																											2,000,000,000					900,000,000																																																																					1,265,000,000				75,000,000			215,000,000	399,000,000	90,000,000
Weighted-average interest rate (as a percent)																																																																																																																																																									1.90%							1.20%		3.40%
Debt instrument face amount																		1,100,000,000				400,000,000				940,000,000		560,000,000		1,000,000,000													247,000,000				900,000,000		1,200,000,000																	2,200,000,000				2,200,000,000				2,200,000,000				300,000,000																																																										500,000,000		1,000,000,000		100,000,000		200,000,000		600,000,000		1,000,000,000									1,000,000,000	190,000,000
Basis of variable interest rate																									Norwegian Interbank Offered Rate	Norwegian Interbank Offered Rate																																																								LIBOR	Base Rate	LIBOR																																																																							LIBOR	LIBOR	LIBOR			LIBOR		LIBOR
Spread on variable rate basis (as a percent)																									7.00%	7.00%																																																								1.625%					0.875%	2.50%	2.00%	1.00%																																																																	1.45%	2.25%	1.45%			0.725%				3.125%	5.125%
Percentage reduction to the calculated variable rate																																																																																			1.00%							1.00%
Commitment fee percentage at period end																																																																															0.275%	0.125%	0.325%			0.375%			0.125%	0.50%
Maximum debt to tangible capitalization ratio																																																																															0.6					0.6
Credit facility available borrowing capacity																																																																															2,000,000,000					900,000,000
Letters of credit issued and outstanding																																																																															24,000,000																																																																															60,000,000	60,000,000
Number of wholly-owned subsidiaries which are obligors to debt instrument																																																																																																																																																																						2	2
Principal amount																																																																					30,000,000		62,000,000		1,722,000,000
Aggregate principal amount of notes issued																															750,000,000																			750,000,000
Redemption price of debt instrument (as a percent)																100.00%													100.00%			100.00%													100.00%			100.00%			100.00%																										100.00%																																																										100.00%		100.00%								100.00%																					100.00%	100.00%
Aggregate principal amount outstanding		12,437,000,000														1,100,000,000									169,000,000		101,000,000		1,000,000,000			750,000,000					381,000,000	420,000,000			246,000,000				900,000,000			1,200,000,000			750,000,000																										300,000,000														12,246,000,000																																												500,000,000		1,000,000,000		100,000,000		57,000,000		600,000,000		1,000,000,000		191,000,000													163,000,000						250,000,000	300,000,000
Aggregate commitment of subsidiary in secured term loan														595,000,000
Credit facility amount outstanding																																																																																																																																																									805,000,000									80,000,000
Debt due to a subsidiary, eliminated in consolidation																																																																																																																																																									402,000,000								399,000,000	52,000,000
Prepayment of debt	148,000,000																				333,000,000																																											11,000,000	1,300,000,000		30,000,000	1,700,000,000			1,700,000,000	478,000,000
Gain (loss) on retirement of debt		2,000,000	(33,000,000)																		2,000,000																																																			(21,000,000)
Restricted investments used as security for debt instruments																																			801,000,000	889,000,000																																																																																																																					23,000,000	23,000,000								19,000,000	16,000,000
NOK exchange rate				5.56
Percentage of total commitment under ADDCL secondary bank credit agreement provided by subsidiary																																																																																																																																																																		65.00%
Fixed interest rate on restricted cash investments (as a percent)																																			4.15%
Weighted-average interest rate (as a percent)																									9.00%	9.00%
Implicit interest rate (as a percent)																																																											7.80%
Additions to property and equipment upon entry into capital lease																																																										716,000,000
Asset capitalized under capital leases																																																										716,000,000
Conversion rate per $1000 principal amount																																																																							6.2905
Convertible debt, principal amount, basis for conversion																																																																							1,000
Conversion price per share of common stock																																																																							$ 158.97
Number of trading days within 30 consecutive trading days required as per the conversion eligibility terms, minimum																																																															20
Number of consecutive trading days required as per the conversion eligibility terms, minimum																																																															30 days
Percentage of the last reported sales price of the entity's common stock that the conversion price must equal or exceed as per conversion eligibility terms, minimum																																																															130.00%
Number of consecutive business days immediately after any five consecutive trading day period during the note measurement period																																																															5 days
Percentage of the average trading price to the average conversion value of the notes																																																															98.00%
Number of consecutive trading days before five consecutive business days during the note measurement period																																																															5 days
Aggregate carrying amount assets pledged						$ 1,400,000,000	$ 1,400,000,000	$ 786,000,000	$ 796,000,000																																																																												$ 2,300,000,000	$ 2,300,000,000

Debt (Details 2) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Scheduled maturities of debt
2013	$ 1,081
2014	274
2015	1,600
2016	1,483
2017	967
Thereafter	7,032
Total debt, excluding unamortized discounts, premiums and fair value adjustments	12,437
Total unamortized discounts, premiums and fair value adjustments	(22)
Total debt	12,459	13,536
Transocean Ltd. and Subsidiaries
Scheduled maturities of debt
2013	1,053
2014	244
2015	1,539
2016	1,448
2017	930
Thereafter	7,032
Total debt, excluding unamortized discounts, premiums and fair value adjustments	12,246
Total unamortized discounts, premiums and fair value adjustments	(22)
Total debt	12,268	12,698
Consolidated variable interest entities
Scheduled maturities of debt
2013	28
2014	30
2015	61
2016	35
2017	37
Total debt, excluding unamortized discounts, premiums and fair value adjustments	191
Total debt	$ 191	$ 838

Debt (Details 3) (USD $) In Millions, except Per Share data, unless otherwise specified	1 Months Ended	12 Months Ended			1 Months Ended	12 Months Ended		1 Months Ended	12 Months Ended
	May 31, 2012	Dec. 31, 2012	Dec. 31, 2010	Dec. 31, 2011	Jan. 31, 2011 1.625% Series A Convertible Senior Notes due December 2037	Dec. 31, 2012 1.625% Series A Convertible Senior Notes due December 2037	Dec. 31, 2010 1.625% Series A Convertible Senior Notes due December 2037	Feb. 29, 2012 1.50% Series B Convertible Senior Notes due December 2037	Dec. 31, 2012 1.50% Series B Convertible Senior Notes due December 2037	Dec. 31, 2011 1.50% Series B Convertible Senior Notes due December 2037	Dec. 31, 2010 1.50% Series B Convertible Senior Notes due December 2037	Dec. 31, 2012 1.50% Series C Convertible Senior Notes due December 2037	Dec. 31, 2011 1.50% Series C Convertible Senior Notes due December 2037	Dec. 31, 2010 1.50% Series C Convertible Senior Notes due December 2037
Carrying amounts of Convertible Senior Notes
Principal amount										$ 30		$ 62	$ 1,722
Unamortized discount													(59)
Total debt		12,459		13,536						30		62	1,663
Convertible debt instrument effective interest rate (as a percent)												5.28%
Remaining period over which discount will be amortized												1 year
Interest expense							58			78	98	84	84	98
Carrying amount of equity component										4		10	276
Aggregate principal amount of debt repurchased	148				11	1,300		30	1,700			1,700		478
Aggregate cash payment made for debt repurchased					11	1,300		30	1,700			1,700		453
Gain (loss) on retirement of debt		(2)	33											21
Gain (loss) on retirement of debt per diluted share														$ 0.07
Adjustment to additional paid-in capital associated with equity components of repurchased notes														$ 8

Derivatives and Hedging (Details) In Millions, unless otherwise specified					12 Months Ended			12 Months Ended
	Dec. 31, 2012 4.95% Senior Notes due November 2015	Dec. 31, 2012 5.25% Senior Notes due March 2013	Dec. 31, 2012 5% Notes due February 2013	Dec. 31, 2012 11% Callable Bonds	Dec. 31, 2012 Interest rate swaps	Dec. 31, 2012 Interest rate swaps Cash flow hedges 11% Callable Bonds Transocean Spitsbergen and Transocean Barents USD ($)	Dec. 31, 2011 Interest rate swaps Cash flow hedges 11% Callable Bonds Transocean Spitsbergen and Transocean Barents USD ($)	Dec. 31, 2012 Derivatives designated as hedging instruments Interest rate swaps Interest expense, net of amounts capitalized USD ($)	Dec. 31, 2011 Derivatives designated as hedging instruments Interest rate swaps Interest expense, net of amounts capitalized USD ($)	Dec. 31, 2010 Derivatives designated as hedging instruments Interest rate swaps Interest expense, net of amounts capitalized USD ($)	Dec. 31, 2012 Derivatives designated as hedging instruments Interest rate swaps Other, net USD ($)	Dec. 31, 2012 Derivatives designated as hedging instruments Interest rate swaps Fair value hedges USD ($)	Dec. 31, 2012 Derivatives designated as hedging instruments Interest rate swaps Fair value hedges Other current assets USD ($)	Dec. 31, 2011 Derivatives designated as hedging instruments Interest rate swaps Fair value hedges Other current assets USD ($)	Dec. 31, 2011 Derivatives designated as hedging instruments Interest rate swaps Fair value hedges Other assets USD ($)	Dec. 31, 2012 Derivatives designated as hedging instruments Interest rate swaps Fair value hedges Pay USD ($)	Dec. 31, 2012 Derivatives designated as hedging instruments Interest rate swaps Fair value hedges Receive USD ($)	Dec. 31, 2012 Derivatives designated as hedging instruments Interest rate swaps Cash flow hedges Other long-term liabilities USD ($)	Dec. 31, 2011 Derivatives designated as hedging instruments Interest rate swaps Cash flow hedges Other long-term liabilities USD ($)	Dec. 31, 2012 Derivatives designated as hedging instruments Interest rate swaps Cash flow hedges Pay USD ($)	Dec. 31, 2012 Derivatives designated as hedging instruments Interest rate swaps Cash flow hedges Receive USD ($)	Dec. 31, 2012 Derivatives designated as hedging instruments Cross-currency swaps Cash flow hedges Other current assets USD ($)	Dec. 31, 2012 Derivatives designated as hedging instruments Cross-currency swaps Cash flow hedges Other assets USD ($)	Dec. 31, 2011 Derivatives designated as hedging instruments Cross-currency swaps Cash flow hedges Other long-term liabilities USD ($)	Dec. 31, 2012 Derivatives designated as hedging instruments Cross-currency swaps Cash flow hedges Pay USD ($)	Dec. 31, 2012 Derivatives designated as hedging instruments Cross-currency swaps Cash flow hedges Receive NOK
Derivatives and Hedging
Interest rate on notes hedged to reduce exposure to changes in fair value (as a percent)	4.95%	5.25%	5.00%	11.00%
Interest rate description to determine the variable interest on debt hedged					three-month London Interbank Offered Rate
Cash proceeds from termination of derivatives												$ 23
Aggregate carrying amount assets pledged						1,500	1,500
Aggregate notional amount																750	750			385	385				102	560
Loss associated with effective portion								(5)	(11)	(12)
Weighted average fixed rate (as a percent)																	5.20%			2.40%					8.90%	11.00%
Weighted average variable rate (as a percent)																3.50%					0.30%
Derivatives at fair value													6	5	31							1	1
Derivatives at fair value																		13	16					7
Gain associated with effective portion											$ 6

Derivatives and Hedging (Details 2) In Millions, unless otherwise specified	12 Months Ended						12 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2011 USD ($)	Dec. 31, 2012 Shelf Drilling USD ($)	Dec. 31, 2012 Nondesignated Shelf Drilling item	Dec. 31, 2012 Nondesignated Interest rate swaps USD ($)	Dec. 31, 2011 Nondesignated Interest rate swaps USD ($)	Dec. 31, 2011 Nondesignated Interest rate swaps Other long-term liabilities USD ($)	Dec. 31, 2012 Nondesignated Interest rate swaps Interest expense, net of amounts capitalized USD ($)	Sep. 30, 2011 Nondesignated Forward exchange contract USD ($)	Dec. 31, 2011 Nondesignated Forward exchange contract Other, net USD ($)	Dec. 31, 2012 Nondesignated Forward exchange contract Cash flow hedges USD ($)	Dec. 31, 2012 Nondesignated Forward exchange contract Cash flow hedges Pay USD ($)	Dec. 31, 2012 Nondesignated Forward exchange contract Cash flow hedges Receive NOK	Dec. 31, 2012 Nondesignated Embedded derivatives Other long-term liabilities USD ($)
Effect on statement of operations resulting from changes in the fair values of derivatives designated as cash flow hedges
Payment for settlement of hedging instruments	$ 78							$ 78
Amount of Preference Shares Received for Sale of Assets		195
Number of embedded derivatives			2
Aggregate notional amount											1,100	6,100
Exchange rate of forward contract (in dollars per share)										5.40
Loss associated with derivatives not designated as hedging instruments							(1)		(78)
Derivatives at fair value						15							2
Cash payment for termination of other undesignated derivative instruments				$ 14	$ 15

Postemployment Benefit Plans (Details) (USD $)	12 Months Ended
Postemployment Benefit Plans (Details) (USD $)	Dec. 31, 2012 plan	Dec. 31, 2011	Dec. 31, 2010
Change in projected benefit obligation
Projected benefit obligation, beginning of period	$ 1,760,000,000	$ 1,498,000,000
Assumed projected benefit obligation		17,000,000
Actuarial (gains) losses, net	117,000,000	149,000,000
Service cost	81,000,000	65,000,000
Interest cost	85,000,000	83,000,000
Foreign currency exchange rate	19,000,000	(1,000,000)
Benefits paid	(71,000,000)	(54,000,000)
Participant contributions	3,000,000	3,000,000
Special termination benefits	1,000,000
Settlements and curtailments	14,000,000	(3,000,000)
Projected benefit obligation, end of period	2,009,000,000	1,760,000,000
Change in plan assets
Fair value of plan assets, beginning of period	1,120,000,000	1,029,000,000
Fair value of acquired plan assets		9,000,000
Actual return on plan assets	144,000,000	31,000,000
Foreign currency exchange rate changes	15,000,000	2,000,000
Employer contributions	159,000,000	103,000,000
Participant contributions	3,000,000	3,000,000
Benefits paid	(71,000,000)	(54,000,000)
Settlement and curtailments		(3,000,000)
Fair value of plan assets, end of period	1,370,000,000	1,120,000,000
Funded status, end of period	(639,000,000)	(640,000,000)
Balance sheet classification, end of period:
Pension asset, non-current	3,000,000
Accrued pension liability, current	30,000,000	11,000,000
Accrued pension liability, non-current	612,000,000	629,000,000
Accumulated other comprehensive income (loss)	(555,000,000)	(550,000,000)
Aggregate projected benefit obligation and fair value of plan assets for plans with a projected benefit obligation in excess of plan assets
Projected benefit obligation	1,992,000,000	1,760,000,000
Fair value of plan assets	1,352,000,000	1,120,000,000
Accumulated benefit obligation for all defined benefit pension plans
Accumulated benefit obligation	1,700,000,000	1,500,000,000
Aggregate accumulated benefit obligation and fair value of plan assets for plans with an accumulated benefit obligation in excess of plan assets
Accumulated benefit obligation	1,648,000,000	1,424,000,000
Fair value of plan assets	1,246,000,000	1,023,000,000
U.S. Plans
Postemployment Benefit Plans
Number of other unfunded supplemental benefit plans	2
Number of funded defined benefit plans assumed in mergers and acquisitions	2
Number of unfunded defined benefit plans assumed in mergers and acquisitions	2
Weighted average assumptions used to determine benefit obligations
Discount rate (as a percent)	4.19%	4.66%
Compensation trend rate (as a percent)	4.21%	4.22%
Weighted-average assumptions used to determine net periodic benefit costs
Discount rate (as a percent)	4.67%	5.49%	5.86%
Expected rate of return (as a percent)	7.47%	8.49%	8.49%
Compensation trend rate (as a percent)	4.22%	4.24%	4.21%
Change in projected benefit obligation
Projected benefit obligation, beginning of period	1,260,000,000	1,068,000,000
Actuarial (gains) losses, net	128,000,000	128,000,000
Service cost	49,000,000	43,000,000	42,000,000
Interest cost	59,000,000	58,000,000	54,000,000
Benefits paid	(45,000,000)	(37,000,000)
Special termination benefits	1,000,000		3,000,000
Projected benefit obligation, end of period	1,452,000,000	1,260,000,000	1,068,000,000
Change in plan assets
Fair value of plan assets, beginning of period	769,000,000	697,000,000
Actual return on plan assets	116,000,000	39,000,000
Employer contributions	108,000,000	70,000,000
Benefits paid	(45,000,000)	(37,000,000)
Fair value of plan assets, end of period	948,000,000	769,000,000	697,000,000
Funded status, end of period	(504,000,000)	(491,000,000)
Balance sheet classification, end of period:
Accrued pension liability, current	3,000,000	3,000,000
Accrued pension liability, non-current	501,000,000	488,000,000
Accumulated other comprehensive income (loss)	(469,000,000)	(437,000,000)
Aggregate projected benefit obligation and fair value of plan assets for plans with a projected benefit obligation in excess of plan assets
Projected benefit obligation	1,452,000,000	1,260,000,000
Fair value of plan assets	948,000,000	769,000,000
Aggregate accumulated benefit obligation and fair value of plan assets for plans with an accumulated benefit obligation in excess of plan assets
Accumulated benefit obligation	1,255,000,000	1,083,000,000
Fair value of plan assets	948,000,000	769,000,000
Non-U.S. Plans
Postemployment Benefit Plans
Number of unfunded defined benefit plans	2
Number of funded benefit plans	7
Weighted average assumptions used to determine benefit obligations
Discount rate (as a percent)	5.37%	4.90%
Compensation trend rate (as a percent)	4.38%	4.30%
Weighted-average assumptions used to determine net periodic benefit costs
Discount rate (as a percent)	5.43%	5.73%	5.67%
Expected rate of return (as a percent)	6.07%	6.42%	6.65%
Compensation trend rate (as a percent)	4.61%	4.62%	4.77%
Change in projected benefit obligation
Projected benefit obligation, beginning of period	447,000,000	374,000,000
Assumed projected benefit obligation		17,000,000
Actuarial (gains) losses, net	(15,000,000)	24,000,000
Service cost	31,000,000	21,000,000	20,000,000
Interest cost	24,000,000	22,000,000	20,000,000
Foreign currency exchange rate	19,000,000	(1,000,000)
Benefits paid	(23,000,000)	(12,000,000)
Participant contributions	2,000,000	2,000,000
Projected benefit obligation, end of period	499,000,000	447,000,000	374,000,000
Change in plan assets
Fair value of plan assets, beginning of period	351,000,000	332,000,000
Fair value of acquired plan assets		9,000,000
Actual return on plan assets	28,000,000	(8,000,000)
Foreign currency exchange rate changes	15,000,000	2,000,000
Employer contributions	49,000,000	29,000,000
Participant contributions	2,000,000	2,000,000
Benefits paid	(23,000,000)	(12,000,000)
Settlement and curtailments		(3,000,000)
Fair value of plan assets, end of period	422,000,000	351,000,000	332,000,000
Funded status, end of period	(77,000,000)	(96,000,000)
Balance sheet classification, end of period:
Pension asset, non-current	3,000,000
Accrued pension liability, current	24,000,000	5,000,000
Accrued pension liability, non-current	56,000,000	91,000,000
Accumulated other comprehensive income (loss)	(80,000,000)	(111,000,000)
Aggregate projected benefit obligation and fair value of plan assets for plans with a projected benefit obligation in excess of plan assets
Projected benefit obligation	482,000,000	447,000,000
Fair value of plan assets	404,000,000	351,000,000
Aggregate accumulated benefit obligation and fair value of plan assets for plans with an accumulated benefit obligation in excess of plan assets
Accumulated benefit obligation	335,000,000	288,000,000
Fair value of plan assets	298,000,000	254,000,000
Non-U.S. Plans \| Aker Drilling
Postemployment Benefit Plans
Number of funded defined benefit plans assumed in mergers and acquisitions	3
OPEB Plans
Weighted average assumptions used to determine benefit obligations
Discount rate (as a percent)	3.63%	4.28%
Weighted-average assumptions used to determine net periodic benefit costs
Discount rate (as a percent)	4.27%	4.94%	5.51%
Health care cost trend rate, initial (as a percent)	8.08%	8.08%	8.00%
Health care cost trend rate, ultimate (as a percent)	5.00%	5.00%	5.00%
Change in projected benefit obligation
Projected benefit obligation, beginning of period	53,000,000	56,000,000
Actuarial (gains) losses, net	4,000,000	(3,000,000)
Service cost	1,000,000	1,000,000
Interest cost	2,000,000	3,000,000
Benefits paid	(3,000,000)	(5,000,000)
Participant contributions	1,000,000	1,000,000
Projected benefit obligation, end of period	58,000,000	53,000,000	56,000,000
Change in plan assets
Employer contributions	2,000,000	4,000,000
Participant contributions	1,000,000	1,000,000
Benefits paid	(3,000,000)	(5,000,000)
Funded status, end of period	(58,000,000)	(53,000,000)
Balance sheet classification, end of period:
Accrued pension liability, current	3,000,000	3,000,000
Accrued pension liability, non-current	55,000,000	50,000,000
Accumulated other comprehensive income (loss)	(6,000,000)	(2,000,000)
Aggregate projected benefit obligation and fair value of plan assets for plans with a projected benefit obligation in excess of plan assets
Projected benefit obligation	58,000,000	53,000,000
Aggregate accumulated benefit obligation and fair value of plan assets for plans with an accumulated benefit obligation in excess of plan assets
Accumulated benefit obligation	$ 58,000,000	$ 53,000,000

Postemployment Benefit Plans (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Fair value of plan assets
Total investments	$ 1,370	$ 1,120	$ 1,029
Transocean Plans
Fair value of plan assets
Total investments	1,370	1,120
Transocean Plans \| Significant observable inputs
Fair value of plan assets
Total investments	947	805
Transocean Plans \| Significant other observable inputs
Fair value of plan assets
Total investments	423	315
Transocean Plans \| Mutual funds
Fair value of plan assets
Total investments	1,225	975
Transocean Plans \| Mutual funds \| Significant observable inputs
Fair value of plan assets
Total investments	941	764
Transocean Plans \| Mutual funds \| Significant other observable inputs
Fair value of plan assets
Total investments	284	211
Transocean Plans \| U.S. equity funds
Fair value of plan assets
Total investments	557	424
Transocean Plans \| U.S. equity funds \| Significant observable inputs
Fair value of plan assets
Total investments	525	395
Transocean Plans \| U.S. equity funds \| Significant other observable inputs
Fair value of plan assets
Total investments	32	29
Transocean Plans \| Non-U.S. equity funds
Fair value of plan assets
Total investments	299	230
Transocean Plans \| Non-U.S. equity funds \| Significant observable inputs
Fair value of plan assets
Total investments	120	91
Transocean Plans \| Non-U.S. equity funds \| Significant other observable inputs
Fair value of plan assets
Total investments	179	139
Transocean Plans \| Bond funds
Fair value of plan assets
Total investments	369	321
Transocean Plans \| Bond funds \| Significant observable inputs
Fair value of plan assets
Total investments	296	278
Transocean Plans \| Bond funds \| Significant other observable inputs
Fair value of plan assets
Total investments	73	43
Transocean Plans \| Other investments
Fair value of plan assets
Total investments	145	145
Transocean Plans \| Other investments \| Significant observable inputs
Fair value of plan assets
Total investments	6	41
Transocean Plans \| Other investments \| Significant other observable inputs
Fair value of plan assets
Total investments	139	104
Transocean Plans \| Cash and money market funds
Fair value of plan assets
Total investments	12	41
Transocean Plans \| Cash and money market funds \| Significant observable inputs
Fair value of plan assets
Total investments	6	41
Transocean Plans \| Cash and money market funds \| Significant other observable inputs
Fair value of plan assets
Total investments	6
Transocean Plans \| Property collective trusts
Fair value of plan assets
Total investments	8	8
Transocean Plans \| Property collective trusts \| Significant other observable inputs
Fair value of plan assets
Total investments	8	8
Transocean Plans \| Investment contracts
Fair value of plan assets
Total investments	125	96
Transocean Plans \| Investment contracts \| Significant other observable inputs
Fair value of plan assets
Total investments	125	96
U.S. Plans
Weighted-average target allocations of the investments
Total target allocation percentage	100.00%
Total actual allocation percentage	100.00%	100.00%
Fair value of plan assets
Total investments	948	769	697
U.S. Plans \| Significant observable inputs
Fair value of plan assets
Total investments	945	767
U.S. Plans \| Significant other observable inputs
Fair value of plan assets
Total investments	3	2
U.S. Plans \| Mutual funds
Fair value of plan assets
Total investments	948	766
U.S. Plans \| Mutual funds \| Significant observable inputs
Fair value of plan assets
Total investments	941	764
U.S. Plans \| Mutual funds \| Significant other observable inputs
Fair value of plan assets
Total investments	3	2
U.S. Plans \| U.S. equity funds
Fair value of plan assets
Total investments	525	395
U.S. Plans \| U.S. equity funds \| Significant observable inputs
Fair value of plan assets
Total investments	525	395
U.S. Plans \| Non-U.S. equity funds
Fair value of plan assets
Total investments	123	93
U.S. Plans \| Non-U.S. equity funds \| Significant observable inputs
Fair value of plan assets
Total investments	120	91
U.S. Plans \| Non-U.S. equity funds \| Significant other observable inputs
Fair value of plan assets
Total investments	3	2
U.S. Plans \| Bond funds
Fair value of plan assets
Total investments	296	278
U.S. Plans \| Bond funds \| Significant observable inputs
Fair value of plan assets
Total investments	296	278
U.S. Plans \| Investment grade fixed income
Weighted-average target allocations of the investments
Total target allocation percentage	35.00%
Total actual allocation percentage	36.00%	36.00%
U.S. Plans \| Other investments
Fair value of plan assets
Total investments	4	3
U.S. Plans \| Other investments \| Significant observable inputs
Fair value of plan assets
Total investments	4	3
U.S. Plans \| Cash and money market funds
Fair value of plan assets
Total investments	4	3
U.S. Plans \| Cash and money market funds \| Significant observable inputs
Fair value of plan assets
Total investments	4	3
U.S. Plans \| Equity securities
Weighted-average target allocations of the investments
Total target allocation percentage	65.00%
Total actual allocation percentage	64.00%	64.00%
Non-U.S. Plans
Weighted-average target allocations of the investments
Total target allocation percentage	100.00%
Total actual allocation percentage	100.00%	100.00%
Fair value of plan assets
Total investments	422	351	332
Non-U.S. Plans \| Significant observable inputs
Fair value of plan assets
Total investments	2	38
Non-U.S. Plans \| Significant other observable inputs
Fair value of plan assets
Total investments	420	313
Non-U.S. Plans \| Mutual funds
Fair value of plan assets
Total investments	282	209
Non-U.S. Plans \| Mutual funds \| Significant other observable inputs
Fair value of plan assets
Total investments	281	209
Non-U.S. Plans \| U.S. equity funds
Fair value of plan assets
Total investments	32	29
Non-U.S. Plans \| U.S. equity funds \| Significant other observable inputs
Fair value of plan assets
Total investments	32	29
Non-U.S. Plans \| Non-U.S. equity funds
Fair value of plan assets
Total investments	176	137
Non-U.S. Plans \| Non-U.S. equity funds \| Significant other observable inputs
Fair value of plan assets
Total investments	176	137
Non-U.S. Plans \| Bond funds
Fair value of plan assets
Total investments	73	43
Non-U.S. Plans \| Bond funds \| Significant other observable inputs
Fair value of plan assets
Total investments	73	43
Non-U.S. Plans \| Investment grade fixed income
Weighted-average target allocations of the investments
Total target allocation percentage	14.00%
Total actual allocation percentage	17.00%	12.00%
Non-U.S. Plans \| Other investments
Weighted-average target allocations of the investments
Total target allocation percentage	37.00%
Total actual allocation percentage	34.00%	41.00%
Fair value of plan assets
Total investments	141	142
Non-U.S. Plans \| Other investments \| Significant observable inputs
Fair value of plan assets
Total investments	2	38
Non-U.S. Plans \| Other investments \| Significant other observable inputs
Fair value of plan assets
Total investments	139	104
Non-U.S. Plans \| Cash and money market funds
Fair value of plan assets
Total investments	8	38
Non-U.S. Plans \| Cash and money market funds \| Significant observable inputs
Fair value of plan assets
Total investments	2	38
Non-U.S. Plans \| Cash and money market funds \| Significant other observable inputs
Fair value of plan assets
Total investments	6
Non-U.S. Plans \| Property collective trusts
Fair value of plan assets
Total investments	8	8
Non-U.S. Plans \| Property collective trusts \| Significant other observable inputs
Fair value of plan assets
Total investments	8	8
Non-U.S. Plans \| Investment contracts
Fair value of plan assets
Total investments	125	96
Non-U.S. Plans \| Investment contracts \| Significant other observable inputs
Fair value of plan assets
Total investments	$ 125	$ 96
Non-U.S. Plans \| Equity securities
Weighted-average target allocations of the investments
Total target allocation percentage	49.00%
Total actual allocation percentage	49.00%	47.00%

- Definition

Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those non-benefit obligations may be considered as reductions of plan assets.

+ References+ Details

Postemployment Benefit Plans (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Net periodic benefit costs, before tax
Service cost	$ 81	$ 65
Interest cost	85	83
Special termination benefits	1
Net periodic benefit costs	149	88	91
Unrecognized accumulated other comprehensive income, before tax
Actuarial loss, net	565	564
Prior service (credit), net	(10)	(12)
Transition obligation, net		(2)
Total	555	550
Accumulated other comprehensive income expected to be recognized during the next fiscal year
Actuarial loss, net	53
Prior service cost (credit), net	(2)
Total amount expected to be recognized	51
Defined benefit plan contributions funded by cash flows from operations
Defined benefit plan contributions funded by cash flows from operations	159	103	118
Projected pension benefits payments
2013	75
2014	62
2015	65
2016	70
2017	74
2018-2022	453
Transocean Plans
Net periodic benefit costs, before tax
Service cost	80	64	62
Interest cost	83	80	74
Expected return on plan assets	(84)	(86)	(75)
Settlements and curtailments	22	3	8
Special termination benefits	1		3
Actuarial losses, net	45	27	17
Prior service cost (credit), net	(1)	(1)	(1)
Transition obligation, net			1
Net periodic benefit costs	146	87	89
Defined benefit plan contributions funded by cash flows from operations
Expected defined plan contributions in 2013	50
U.S. Plans
Net periodic benefit costs, before tax
Service cost	49	43	42
Interest cost	59	58	54
Expected return on plan assets	(62)	(63)	(58)
Settlements and curtailments	3	2	5
Special termination benefits	1		3
Actuarial losses, net	41	23	13
Prior service cost (credit), net	(2)	(1)	(1)
Net periodic benefit costs	89	62	58
Unrecognized accumulated other comprehensive income, before tax
Actuarial loss, net	477	447
Prior service (credit), net	(8)	(10)
Total	469	437
Accumulated other comprehensive income expected to be recognized during the next fiscal year
Actuarial loss, net	48
Prior service cost (credit), net	(1)
Total amount expected to be recognized	47
Projected pension benefits payments
2013	43
2014	47
2015	51
2016	55
2017	59
2018-2022	349
Non-U.S. Plans
Net periodic benefit costs, before tax
Service cost	31	21	20
Interest cost	24	22	20
Expected return on plan assets	(22)	(23)	(17)
Settlements and curtailments	19	1	3
Actuarial losses, net	4	4	4
Prior service cost (credit), net	1
Transition obligation, net			1
Net periodic benefit costs	57	25	31
Unrecognized accumulated other comprehensive income, before tax
Actuarial loss, net	80	113
Transition obligation, net		(2)
Total	80	111
Accumulated other comprehensive income expected to be recognized during the next fiscal year
Actuarial loss, net	4
Total amount expected to be recognized	4
Projected pension benefits payments
2013	28
2014	11
2015	10
2016	11
2017	11
2018-2022	82
OPEB Plans
Net periodic benefit costs, before tax
Service cost	1	1
Interest cost	2	3
Net periodic benefit costs	3	1	2
Unrecognized accumulated other comprehensive income, before tax
Actuarial loss, net	8	4
Prior service (credit), net	(2)	(2)
Total	6	2
Accumulated other comprehensive income expected to be recognized during the next fiscal year
Actuarial loss, net	(1)
Prior service cost (credit), net	(1)
Defined benefit plan contributions funded by cash flows from operations
Expected defined plan contributions in 2013	4
Projected pension benefits payments
2013	4
2014	4
2015	4
2016	4
2017	4
2018-2022	$ 22

Postemployment Benefit Plans (Details 4) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012 plan	Dec. 31, 2011	Dec. 31, 2010
Defined contribution plans
Number of defined contribution plans sponsored by the entity (in plans)	3
Contribution to plan recognized during the period
Contribution expense	$ 85	$ 82	$ 69
U.S. Savings Plan and the Non-U.S. Savings Plan \| Maximum
Defined contribution plans
Matching contribution as a percentage of employee's base salary	6.00%
U.S. Savings Plan
Defined contribution plans
Number of defined contribution plans sponsored by the entity (in plans)	1
Non-U.S. Savings Plan
Defined contribution plans
Number of defined contribution plans sponsored by the entity (in plans)	1
Non-U.S. Pension Plan
Defined contribution plans
Number of defined contribution plans sponsored by the entity (in plans)	1
Non-U.S. Pension Plan \| Maximum
Defined contribution plans
Matching contribution as a percentage of employee's base salary	6.50%
Non-U.S. Pension Plan \| Minimum
Defined contribution plans
Matching contribution as a percentage of employee's base salary	4.50%

Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Lease obligations
Rental expenses for all leases, including leases with terms of less than one year	$ 97	$ 169	$ 98
Capital lease, future minimum rental payments
2013	66
2014	72
2015	72
2016	72
2017	73
Thereafter	846
Total future minimum rental payment	1,201
Less amount representing imputed interest	(544)
Present value of future minimum rental payments under capital leases	657
Less current portion included in debt due within one year	(20)
Long-term capital lease obligation	637
Operating leases, future minimum rental payments
2013	42
2014	38
2015	24
2016	21
2017	11
Thereafter	95
Total future minimum rental payment	231
Aggregate carrying amount of assets held under capital lease
Property and equipment, cost	745	742
Accumulated depreciation	(64)	(44)
Property and equipment, net	681	698
Depreciation expense for assets held under capital lease	$ 20	$ 20	$ 23

Commitments and Contingencies (Details 2) (New builds, USD $) In Millions, unless otherwise specified	Dec. 31, 2012
New builds
Future Purchase obligations
2013	$ 1,896
2014	447
2015	749
2016	674
Total	$ 3,766

Commitments and Contingencies (Details 3)	12 Months Ended								1 Months Ended	12 Months Ended				12 Months Ended		0 Months Ended		1 Months Ended							12 Months Ended				12 Months Ended							12 Months Ended
Commitments and Contingencies (Details 3)	Dec. 31, 2010 USD ($)	Dec. 31, 2012 Macondo well incident USD ($)	Dec. 31, 2011 Macondo well incident USD ($)	Apr. 22, 2010 Macondo well incident mi person	Dec. 31, 2012 Macondo well incident Insurance coverage claim	Apr. 22, 2010 Macondo well incident Insurance coverage USD ($)	Dec. 31, 2012 Macondo well incident Wrongful death and personal injury lawsuit	Dec. 31, 2012 Macondo well incident Economic loss lawsuit	Jun. 30, 2010 Macondo well incident Shareholder derivative claims item	Dec. 31, 2011 Macondo well incident Shareholder derivative claims lawsuit	Dec. 15, 2010 Macondo well incident U.S. Department of Justice claims USD ($) bbl	Dec. 31, 2012 Macondo well incident Wreck removal USD ($)	Dec. 31, 2012 Macondo well incident Contractual indemnity USD ($)	Dec. 31, 2012 Macondo well incident Notices of alleged non-compliance note	May 05, 2010 Macondo well incident State and other government claims lawsuit item	Aug. 08, 2012 Brazil Frade field incident USD ($) lawsuit plaintiff	Aug. 08, 2012 Brazil Frade field incident BRL	Jul. 31, 2012 Brazil Frade field incident	May 31, 2012 Brazil Frade field incident judge	Apr. 30, 2012 Brazil Frade field incident USD ($)	Apr. 30, 2012 Brazil Frade field incident BRL	Mar. 31, 2012 Brazil Frade field incident BRL	Dec. 31, 2011 Brazil Frade field incident USD ($)	Dec. 31, 2011 Brazil Frade field incident BRL	Dec. 31, 2012 Brazil Frade field incident claim	Mar. 21, 2012 Brazil Frade field incident entity	Mar. 15, 2012 Brazil Frade field incident l km m	Dec. 21, 2011 Brazil Frade field incident employee individual count	Dec. 31, 2012 Asbestos litigation USD ($) lawsuit plaintiff subsidiary	Sep. 30, 2006 Rio de Janeiro tax assessment USD ($) subsidiary	Sep. 30, 2006 Rio de Janeiro tax assessment BRL	Dec. 31, 2010 Brazilian import license assessment USD ($) subsidiary	Dec. 31, 2010 Brazilian import license assessment BRL	Dec. 31, 2012 Hazardous waste disposal sites subsidiary	Dec. 31, 2012 Retained risk USD ($)	Dec. 31, 2012 Letters of credit and surety bonds USD ($)	Dec. 31, 2011 Letters of credit and surety bonds USD ($)
Contingencies
Number of persons declared dead				11
Number of miles Deepwater Horizon was off coast of Louisiana				41
Estimated liability recorded based on probable losses related to the rig explosion and fire incident		$ 1,900,000,000	$ 1,200,000,000
Proceeds from insurance recoveries	560,000,000	15,000,000
Proceeds from insuranced received by third party		84,000,000
Portion of liability related to the rig explosion and fire incident recoverable from insurance		141,000,000	233,000,000
Percentage of non-operating interest of Anadarko in the Macondo well		25.00%
Percentage of non-operating interest of MOEX in the Macondo well		10.00%
Insured status under excess liability insurance program						950,000,000
Deductible amount under excess liability insurance program						15,000,000
Amount covered by fifth layer of excess liability insurance program						250,000,000
Amount covered by third layer of excess liability insurance program						200,000,000
Amount covered by fourth layer of excess liability insurance program						200,000,000
Amount covered by second layer of excess liability insurance program						150,000,000
Amount covered by first layer of excess liability insurance program						150,000,000
Amount covered by self insured layer of excess liability insurance program						50,000,000
Number of actions or claims that were pending					383		9	153																					21
Number of shareholders derivative suits									2	2
Number of putative class action complaints filed alleging, among other things, economic losses as a result of environmental pollution arising out of the Macondo well incident (in lawsuits)								188
Civil penalties per barrel, Maximum (in dollars per barrel)											1,100
Civil penalties per barrel for gross negligence or willful misconduct, Maximum (in dollars per barrel)											4,300
U.S. government's maximum estimate of barrels of oil discharged and subject to penalties											4,100,000
Percentage of asset value covered												25.00%
Amount agreed to indemnify and defend operator of rig													15,000,000
Area of fissure of which seepage is noted																											800
Distance from the November incident																											3
Volume of seepage																											5
Amount sought under civil public action																35,000	72,000			10,000,000,000	20,000,000,000		10,000,000,000	20,000,000,000
Number of judges																			3
Number of individuals for whom indictment recommended under investigation report filed																												17
Number of the entity's employees for whom indictment recommended under investigation report filed																												5
Number of counts on which indictment recommended under investigation report filed																												4
Number of counts alleging environmental offenses on which indictment recommended under investigation report filed																												3
Number of counts alleging false statements by Chevron, on which indictment recommended under investigation report filed																												1
Number of companies for whom indictment recommended under investigation report filed																										2
Bail amount requested by federal prosecutor in Brazilian town of Campos In Rio De Janerio State from companies																						10,000,000
Bail amount requested by federal prosecutor in Brazilian town of Campos In Rio De Janerio State from individuals																						1,000,000
Term of preliminary injunction from the date of service																		30 days
Amount excludable per occurrence, claim arising from negligence																							250,000
Number of private civil lawsuits filed																43	43
Number of additional lawsuits filed																									49
Number of claimants																217	217												769
Number of total cases in which there may be an indirect interest regarding asbestos litigation (in lawsuits)																													26
Number of cases being governed for discovery and trial setting and in which the Company is named defendant																													14
Number of cases scheduled for trial and pre-trail discovery which was scheduled to take place in current year																													1
Number of cases in which ruling has now been obtained and the Company cannot be sued for punitive damages																													3
Number of cases gone to trial against defendants who allegedly manufactured or distributed drilling mud additives																													7
Number of cases gone to trial against defendants, resulting in defense verdict																													2
Number of cases gone to trial against defendants, ended with hung jury																													1
Number of cases gone to trial against defendants, resulting in verdict for the plaintiff																													4
Number of cases resulting in substantial verdict in favor of the plaintiff																													2
Number of remaining plaintiff verdicts are under appeal by the defendants																													2
Number of subsidiaries involved in lawsuits arising from design, construction and refurbishment of major industrial complexes																													1
Number of lawsuits alleging personal injury from asbestos exposure for subsidiary involved in design, construction and refurbishment of major industrial complexes																													906
Estimated number of plaintiffs in lawsuits alleging personal injury from asbestos exposure for subsidiary involved in design, construction and refurbishment of major industrial complexes																													2,022
Insurance limits potentially available for damages in lawsuits regarding personal injury from asbestos exposure for subsidiary involved in design, construction and refurbishment of major industrial																													1,000,000,000
Tax assessment from state tax authorities																														185,000,000	379,000,000	238,000,000	487,000,000
Total amount of tax assessment from state tax authorities																																15,000,000	30,000,000
Number of subsidiaries involved in tax assessment relating to import license																														1	1
Number of subsidiaries involved in federal tax assessment relating to import license																																1	1
Percentage of liability for remediation and related costs																																		8.00%
Number of subsidiaries ordered by California Regional Water Quality Control Board to develop testing plan for Alhambra, California site																																		1
Minimum number of subsidiaries likely to be named potentially responsible party by US Environmental Protection Agency for superfund site (in counts)																																		1
Asset value covered by wreck removal insurance												140,000,000
Aggregate value of drilling rig fleet																																			29,300,000,000
Per occurrence insurance deductible on hull and machinery																																			125,000,000
Maximum aggregate insurance deductible on hull and machinery per year																																			200,000,000
Maximum percentage of asset insured value covered by damage mitigation insurance																																			25.00%
Maximum percentage of rig's insured value covered by wreck removal insurance																																			25.00%
Commercial market excess liability coverage																																			775,000,000
Per occurrence deductible on crew personal injury liability and collision liability claims																																			10,000,000
Per occurrence deductible on other third-party non-crew claims																																			5,000,000
Aggregate per occurrence deductible on other third party non-crew claims																																			50,000,000
Liability loss limit for commercial market excess liability coverage																																			825,000,000
Additional insurance that covers expenses that would otherwise be assumed by the well owner																																			100,000,000
Maximum liability amount for well control and re-drilling liability related to blowouts																																			50,000,000
Outstanding letters of credit																																				522,000,000	650,000,000
Letters of credit issued under committed and uncommitted credit lines																																				113,000,000
Term of letters of credit																																				3 years
Surety bonds outstanding																																				$ 11,000,000	$ 12,000,000
Notices of alleged non-compliance
Number of notices issued by the Department of the Interior's Bureau of Safety and Environmental Enforcement														4
Number of Gulf Coast states Attorneys General seeking recovery of clean up costs and damages															5
Number of Atlantic Coast states Attorneys General wanting assurances of financial responsibility for potential damages															11

Redeemable Noncontrolling Interest (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended
	May 31, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Aug. 31, 2012	Feb. 29, 2012
Redeemable Noncontrolling Interest
Adjustment to retained earnings within shareholders' equity		$ 106
Adjustment to increase the liability	25
Issuance of shares in exchange for noncontrolling interest	8.7
Adjustment to share capital	134
Adjustment to additional paid in capital	233
Extinguishment of TPDI Notes payable	148
Accrued and unpaid interest	14
Percentage of TPDI's working capital	50.00%
Final Cash Settlement for Noncontrolling Interest					72
Percentage interest in joint venture (TPDI) that is held by an unaffiliated party (Quantum)						50.00%
Redeemable noncontrolling interest
Balance, beginning of period		116	41
Reclassification from noncontrolling interest				26
Net income attributable to noncontrolling interest		13	78	29
Other comprehensive loss attributable to noncontrolling interest			(3)	(14)
Fair value adjustment of redeemable noncontrolling interest		106
Reclassification to accumulated other comprehensive loss		17
Reclassification to other current liabilities		(252)
Balance, end of period			$ 116	$ 41

Shareholders' Equity (Details)	1 Months Ended						12 Months Ended
Shareholders' Equity (Details)	May 31, 2012	Mar. 31, 2012 USD ($)	Dec. 31, 2011 USD ($) installment	Dec. 31, 2011 CHF	May 31, 2009 CHF	Dec. 31, 2008 subsidiary	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($) installment	Dec. 31, 2010 USD ($)	Dec. 31, 2010 CHF	Dec. 31, 2012 CHF	May 31, 2011 USD ($) installment
Distribution of qualifying additional paid-in capital
Cash distribution approved in the form of additional paid-in capital (in dollars per share)												$ 3.16
Number of quarterly installments (in installments)												4
Amount of installment (in dollars per share)												$ 0.79
Number of installments paid (in installments)			3	3				3
Installment of dividend paid		$ 278,000,000					$ 278,000,000	$ 763,000,000
Equity Issuance
Issuance of shares to Quantum in exchange for redeemable noncontrolling interest	8,700,000
Issuance of shares (in shares)			29,900,000	29,900,000
Price per share issued under public offering			$ 40.50	37.19
Share repurchase USD exchange rate			1.00					1.00
Share repurchase CHF average exchange rate				0.9183
Proceeds from issuance of shares, net of underwriting discounts and commissions, issuance costs and the Swiss Federal Issuance tax			1,200,000,000					1,211,000,000
Shares held in treasury
Authorized amount for repurchase of shares					3,500,000,000		3,800,000,000
Share repurchase USD exchange rate			1.00					1.00
Share repurchase CHF exchange rate											0.92
Treasury shares purchased under share repurchase program									2,900,000	2,900,000
Aggregate purchase price									$ 240,000,000	257,000,000
Treasury shares			2,863,267	2,863,267				2,863,267			2,863,267
Shares held by subsidiary
Number of issued shares to a subsidiary to satisfy obligations in connection with awards granted under incentive plans or other rights to acquire shares of stocks						16,000,000
Number of subsidiaries to whom shares were issued						1
Number of shares held by subsidiary			12,500,000	12,500,000				12,500,000			11,500,000

Shareholders' Equity (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Changes in accumulated other comprehensive loss
Accumulated other comprehensive loss, balance beginning of period	$ (496)
Reclassification from redeemable noncontrolling interest	(17)
Accumulated other comprehensive loss, balance end of period	(521)		(332)
Unrecognized components of net periodic benefit costs
Changes in accumulated other comprehensive loss
Accumulated other comprehensive loss, balance beginning of period	(501)	(335)
Other comprehensive income (loss) attributable to controlling interest	(10)	(166)
Accumulated other comprehensive loss, balance end of period	(511)	(501)
Unrecognized gains (losses) on derivative investments
Changes in accumulated other comprehensive loss
Accumulated other comprehensive loss, balance beginning of period	7	5
Reclassification from redeemable noncontrolling interest	(17)
Other comprehensive income (loss) attributable to controlling interest		2
Accumulated other comprehensive loss, balance end of period	(10)	7
Unrecognized gains (losses) on marketable securities
Changes in accumulated other comprehensive loss
Accumulated other comprehensive loss, balance beginning of period	(2)
Other comprehensive income (loss) attributable to controlling interest	2
Accumulated other comprehensive loss, balance end of period			(2)
Total
Changes in accumulated other comprehensive loss
Accumulated other comprehensive loss, balance beginning of period	(496)	(332)
Reclassification from redeemable noncontrolling interest	(17)
Other comprehensive income (loss) attributable to controlling interest	(8)	(164)	3
Accumulated other comprehensive loss, balance end of period	$ (521)	$ (496)	$ (332)

- Definition

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 14

-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e681-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 11

-URI http://asc.fasb.org/extlink&oid=20435746&loc=d3e637-108580

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 14A

-URI http://asc.fasb.org/extlink&oid=20435746&loc=SL7669686-108580

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 12

-Paragraph 10

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 31

-Article 5

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS115-1/124-1

-Paragraph 15D

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 7: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 130

-Paragraph 14, 17, 26

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 8: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

+ Details

- Definition

Net of tax amount of other comprehensive income (loss) attributable to the parent entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

-Paragraph 38

-Subparagraph c(3)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

-Paragraph 30

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 45

-Paragraph 20

-URI http://asc.fasb.org/extlink&oid=7656940&loc=SL4569643-111683

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 45

-Paragraph 19

-URI http://asc.fasb.org/extlink&oid=7656940&loc=SL4569616-111683

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 51

-Paragraph 29

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 810

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (c)(3)

-URI http://asc.fasb.org/extlink&oid=18733093&loc=SL4573702-111684

+ Details

Share-Based Compensation Plans (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Share Based Compensation Plans
Shares authorized under the plan	36,000,000
Shares available for grant under the plan	10,900,000
Total unrecognized compensation costs related to all unvested share based awards	$ 95
Weighted average period over compensation costs are expected to be recognized	1 year 9 months 18 days
Additional share based compensation expense in connection with modification of share-based awards	4	3	12
Stock options
Share Based Compensation Plans
General term of awards after they are vested	10 years
Option valuation assumptions
Dividend yield (as a percent)		4.00%	4.00%
Expected price volatility (as a percent)	43.00%	40.00%	39.00%
Risk free interest rate (as a percent)	0.87%	1.97%	2.30%
Expected life of options	5 years	4 years 10 months 24 days	4 years 8 months 12 days
Granted (in dollars per share)	$ 18.87	$ 19.75	$ 30.03
Weighted-average grant-date fair value per share
Granted (in dollars per share)	$ 18.87	$ 19.75	$ 30.03
Stock appreciation rights
Share Based Compensation Plans
General term of awards after they are vested	10 years
Time-Based Awards
Share Based Compensation Plans
Vesting period	3 years
Total grant date fair value of the time-based units that were forfeited		13	8
Equity instruments other than options activity
Forfeited (in shares)		(163,439)	(106,691)
Time-Based Awards \| Stock options
Option valuation assumptions
Granted (in dollars per share)	$ 18.87	$ 19.75	$ 30.03
Stock option activity
Outstanding at the beginning of the period (in shares)	1,579,284
Granted (in shares)	395,673	194,342	253,288
Exercised (in shares)	(264,707)	(210,997)	(289,445)
Forfeited (in shares)	(55,533)
Expired (in shares)	(38,662)
Outstanding at the end of the period (in shares)	1,616,055	1,579,284
Vested and exercisable at the end of the period (in shares)	1,088,127
Total grant-date fair value of awards vested	5	8	12
Weighted-average exercise price per share
Outstanding at the beginning of the period (in dollars per share)	$ 70.16
Granted (in dollars per share)	$ 50.79
Exercised (in dollars per share)	$ 36.50
Forfeited (in dollars per share)	$ 59.65
Expired (in dollars per share)	$ 53.51
Outstanding at the end of the period (in dollars per share)	$ 71.69	$ 70.16
Vested and exercisable at the end of the period (in dollars per share)	$ 77.24
Weighted-average remaining contractual term
Outstanding at the beginning of the period	6 years 3 months 18 days	5 years 5 months 5 days
Outstanding at the end of the period	6 years 3 months 18 days	5 years 5 months 5 days
Vested and exercisable at the end of the period	5 years 1 month 24 days
Aggregate intrinsic value (in millions)
Exercised during the period	3	5	11
Additional disclosure
Unvested options outstanding (in shares)	348,666	396,997	470,400
Weighted-average grant-date fair value per share
Granted (in dollars per share)	$ 18.87	$ 19.75	$ 30.03
Time-Based Awards \| Restricted shares
Equity instruments other than options activity
Vested (in shares)		(3,939)	(92,573)
Additional disclosure
Total grant date fair value		1	10
Time-Based Awards \| Deferred units
Equity instruments other than options activity
Outstanding at the beginning of the period (in shares)	1,939,840
Granted (in shares)	2,183,853	1,090,747	1,055,367
Vested (in shares)	(1,064,359)	(832,252)	(559,339)
Forfeited (in shares)	(189,283)
Outstanding at the end of the period (in shares)	2,870,051	1,939,840
Weighted-average grant-date fair value per share
Outstanding at the beginning of the period (in dollars per share)	$ 74.78
Granted (in dollars per share)	$ 50.07	$ 77.55	$ 76.83
Vested (in dollars per share)	$ 71.57
Forfeited (in dollars per share)	$ 60.73
Outstanding at the end of the period (in dollars per share)	$ 58.09	$ 74.78
Additional disclosure
Total grant date fair value	74	66	45
Time-Based Awards \| Stock appreciation rights
Equity instruments other than options activity
Outstanding at the beginning of the period (in shares)	187,739
Outstanding at the end of the period (in shares)	187,739	187,739
Vested and exercisable at the end of the period (in shares)	187,739
Weighted average exercise price per share
Outstanding at the beginning of the period (in dollars per share)	$ 93.39	$ 93.39
Vested and exercisable at the end of the period (in dollars per share)	$ 93.39
Outstanding at the end of the period (in dollars per share)	$ 93.39	$ 93.39
Weighted-average remaining contractual term
Weighted-average remaining contractual term, at the end of the period	3 years 9 months 4 days	4 years 9 months 4 days
Vested and exercisable, at the end of the period	3 years 9 months 4 days
Additional disclosure
Exercises (in shares)		1,400
Performance-Based Awards \| Stock options
Stock option activity
Outstanding at the beginning of the period (in shares)	179,262
Outstanding at the end of the period (in shares)	179,262	179,262
Vested and exercisable at the end of the period (in shares)	179,262
Weighted-average exercise price per share
Outstanding at the beginning of the period (in dollars per share)	$ 75.30
Outstanding at the end of the period (in dollars per share)	$ 75.30	$ 75.30
Vested and exercisable at the end of the period (in dollars per share)	$ 75.30
Weighted-average remaining contractual term
Outstanding at the beginning of the period	3 years 2 months 19 days	4 years 2 months 23 days
Outstanding at the end of the period	3 years 2 months 19 days	4 years 2 months 23 days
Vested and exercisable at the end of the period	3 years 2 months 19 days
Two-year Awards
Share Based Compensation Plans
Measurement period	2 years
Number of equal installments vesting	3
Number of years subsequent to first installment	2 years
Three-year Awards
Share Based Compensation Plans
Measurement period	3 years
Number of equal installments vesting	1
Market-Based Awards
Additional disclosure
Total grant date fair value	$ 24
Market-Based Awards \| Deferred units
Equity instruments other than options activity
Outstanding at the beginning of the period (in shares)	415,947
Granted (in shares)	163,319	98,797	122,934
Vested (in shares)	(318,926)
Forfeited (in shares)	(28,889)
Outstanding at the end of the period (in shares)	231,451	415,947
Weighted-average grant-date fair value per share
Outstanding at the beginning of the period (in dollars per share)	$ 75.98
Granted (in dollars per share)	$ 58.52	$ 78.69	$ 82.55
Vested (in dollars per share)	$ 75.18
Forfeited (in dollars per share)	$ 70.04
Outstanding at the end of the period (in dollars per share)	$ 65.50	$ 75.98

Supplemental Balance Sheet Information (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Other current liabilities
Accrued payroll and employee benefits	$ 421	$ 328
Distribution payable		278
Deferred revenue	214	171
Deferred revenue of consolidated variable interest entities	21	16
Accrued taxes, other than income	150	142
Accrued interest	122	132
Contingent liabilities	1,958	1,243
Other	47	65
Total other current liabilities	2,933	2,375	895
Other long-term liabilities
Long-term income taxes payable	584	751
Accrued pension liabilities	558	579
Deferred revenue	174	236
Deferred revenue of consolidated variable interest entities	72	85
Drilling contract intangibles	60	103
Accrued retiree life insurance and medical benefits	54	49
Other	102	122
Total other long-term liabilities	$ 1,604	$ 1,925	$ 1,791

Supplemental Cash Flow Information (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended
	May 31, 2012	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010 drillingunit
Changes in operating assets and liabilities
Decrease (increase) in accounts receivable		$ (139)	$ (174)	$ 386
Increase in other current assets		(73)	(73)	(75)
Decrease (increase) in other assets		12	26	(40)
Increase in accounts payable and other current liabilities		931	978	197
Decrease in other long-term liabilities		(63)	(34)	(52)
Change in income taxes receivable / payable, net		(156)	80	(37)
Net cash provided by (used in) operating activities		512	803	379
Certain cash operating activities
Cash payments for interest		719	501	455
Cash payments for income taxes		347	338	493
Non-cash investing and financing activities
Capital expenditures, accrued at end of period		123	62	66
Issuance of shares in exchange for redeemable noncontrolling interest		367
Non-cash proceeds received for the sale of assets		194		134
Significant Acquisitions and Disposals
Issuance of shares in exchange for redeemable noncontrolling interest (in shares)	8.7
Number of Midwater Floaters sold (in drilling units)				2
Proceeds from disposal of assets, net		191	14	60
Midwater Floaters
Significant Acquisitions and Disposals
Number of Midwater Floaters sold (in drilling units)				2
Proceeds from disposal of assets, net				38
Number of Notes Receivable Noncash, Proceeds from Sale of Assets				2
Non-cash proceeds from sale of assets				165
Shelf Drilling International Holdings, Ltd
Significant Acquisitions and Disposals
Proceeds from disposal of assets, net		568
Non-cash proceeds from sale of assets		$ 196
Number of Drilling Units Sold		38

Financial Instruments (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Financial instruments
Restricted cash investments	$ 857,000,000	$ 934,000,000
Shelf Drilling
Preference shares
Number of drilling units sold	38
Carrying amount
Financial instruments
Cash and cash equivalents	5,134,000,000	4,017,000,000
Notes and other loans receivable	142,000,000	154,000,000
Preference shares	196,000,000
Restricted cash investments	857,000,000	934,000,000
Long-term debt, including current maturities	12,268,000,000	12,698,000,000
Derivative instruments, assets	8,000,000	36,000,000
Derivative instruments, liabilities	15,000,000	38,000,000
Debt
Fixed rate debt	11,700,000,000	11,900,000,000
Variable-rate debt	579,000,000	761,000,000
Carrying amount \| Other current assets
Financial instruments
Notes and other loans receivable	35,000,000	37,000,000
Carrying amount \| Other assets
Financial instruments
Notes and other loans receivable	107,000,000	117,000,000
Carrying amount \| TPDI and ADDCL Credit Facilities
Financial instruments
Restricted cash investments	60,000,000	45,000,000
Carrying amount \| Aker Drilling
Financial instruments
Restricted cash investments	797,000,000	889,000,000
Carrying amount \| Consolidated Variable Interest Entities
Financial instruments
Long-term debt of consolidated variable interest entities, including current maturities	191,000,000	838,000,000
Fair value
Financial instruments
Cash and cash equivalents	5,134,000,000	4,017,000,000
Notes and other loans receivable	142,000,000	154,000,000
Preference shares	196,000,000
Restricted cash investments	903,000,000	975,000,000
Fair value \| Level 2
Financial instruments
Long-term debt, including current maturities	13,899,000,000	13,074,000,000
Derivative instruments, assets	8,000,000	36,000,000
Derivative instruments, liabilities	15,000,000	38,000,000
Debt
Fixed rate debt	13,300,000,000	12,200,000,000
Variable-rate debt	579,000,000	761,000,000
Fair value \| Level 2 \| Aker Drilling
Financial instruments
Restricted cash investments	843,000,000	930,000,000
Fair value \| Level 2 \| Consolidated Variable Interest Entities
Financial instruments
Long-term debt of consolidated variable interest entities, including current maturities	$ 191,000,000	$ 838,000,000

Risk Concentration (Details)	12 Months Ended
Risk Concentration (Details)	Dec. 31, 2012 item
Interest rate risk
Maturity period of debt for exposure to changes in market interest rates, minimum	1 year
Labor Agreements
Number of employees	18,400
Number of employees engaged through contract labor providers	1,700
Number of persons working under operating agreements with Shelf Drilling	3,000

Operating Segments, Geographic Analysis and Major Customers (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012 item	Dec. 31, 2011	Dec. 31, 2010
Operating Segments, Geographic Analysis and Major Customers
Number of operating segments									2
Segments, Geographical Analysis and Major Customers
Operating revenues	$ 2,326	$ 2,431	$ 2,329	$ 2,110	$ 2,133	$ 1,974	$ 2,051	$ 1,869	$ 9,196	$ 8,027	$ 7,949
U.S.
Segments, Geographical Analysis and Major Customers
Operating revenues									2,472	1,971	1,937
Norway
Segments, Geographical Analysis and Major Customers
Operating revenues									1,174	897	765
Brazil
Segments, Geographical Analysis and Major Customers
Operating revenues									1,114	1,019	1,288
U.K.
Segments, Geographical Analysis and Major Customers
Operating revenues									1,028	1,099	1,097
Other countries
Segments, Geographical Analysis and Major Customers
Operating revenues									$ 3,408	$ 3,041	$ 2,862
Threshold of operating revenues for reporting individually as a country (as a percent)	10.00%								10.00%

Operating Segments, Geographic Analysis and Major Customers (Details 2) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Segments, Geographical Analysis and Major Customers
Long-lived assets	$ 20,880,000,000	$ 20,788,000,000
Long-lived assets in Switzerland	7,000,000	8,000,000
U.S.
Segments, Geographical Analysis and Major Customers
Long-lived assets	7,395,000,000	6,553,000,000
Brazil
Segments, Geographical Analysis and Major Customers
Long-lived assets	2,285,000,000	2,185,000,000
Norway
Segments, Geographical Analysis and Major Customers
Long-lived assets	2,072,000,000	2,067,000,000
Other countries
Segments, Geographical Analysis and Major Customers
Long-lived assets	$ 9,128,000,000	$ 9,983,000,000
Threshold for long lived assets for reporting individually as a country (as a percent)	10.00%

Operating Segments, Geographic Analysis and Major Customers (Details 3) (Total operating revenues, Operating revenues)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Chevron Corporation
Concentration Risk
Percentage of concentration	11.00%
BP
Concentration Risk
Percentage of concentration	11.00%	11.00%	11.00%
Petrobras
Concentration Risk
Percentage of concentration	10.00%		11.00%

Condensed Consolidating Financial Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Condensed Consolidating Financial Information
Operating revenues	$ 2,326	$ 2,431	$ 2,329	$ 2,110	$ 2,133	$ 1,974	$ 2,051	$ 1,869	$ 9,196	$ 8,027	$ 7,949
Cost and expenses									7,511	7,576	5,474
Loss on impairment									(140)	(5,201)
Gain (loss) on disposal of assets, net									36	(12)	255
Operating income (loss)	541	811	(142)	371	(5,811)	303	380	366	1,581	(4,762)	2,730
Other income (expense), net
Interest expense, net									(667)	(577)	(544)
Equity in earnings										5	8
Other, net									(48)	(99)	(31)
Total other income (expense), net									(715)	(676)	(575)
Income (loss) from continuing operations before income tax expense									866	(5,438)	2,155
Income tax expense									50	324	292
Income (loss) from continuing operations	432	533	(303)	154	(6,094)	(19)	171	180	816	(5,762)	1,863
Income (loss) from discontinued operations, net of tax									(1,027)	85	(894)
Net income (loss)									(211)	(5,677)	969
Net income (loss) attributable to noncontrolling interest									8	77	43
Net income (loss) attributable to controlling interest	456	(381)	(304)	10	(6,165)	(32)	124	319	(219)	(5,754)	926
Other comprehensive income (loss) before income taxes									(1)	(181)	(9)
Income taxes related to other comprehensive income (loss)									(7)	13	(9)
Other comprehensive income (loss), net of income taxes									(8)	(168)	(18)
Total comprehensive income (loss)									(219)	(5,845)	951
Total comprehensive income (loss) attributable to noncontrolling interest									8	73	22
Total comprehensive income (loss) attributable to controlling interest									(227)	(5,918)	929
Parent Guarantor
Condensed Consolidating Financial Information
Cost and expenses									54	44	45
Operating income (loss)									(54)	(44)	(45)
Other income (expense), net
Interest expense, net									(12)	(11)	1
Equity in earnings									(153)	(5,699)	970
Total other income (expense), net									(165)	(5,710)	971
Income (loss) from continuing operations before income tax expense									(219)	(5,754)	926
Income (loss) from continuing operations									(219)	(5,754)	926
Net income (loss)									(219)	(5,754)	926
Net income (loss) attributable to controlling interest									(219)	(5,754)	926
Other comprehensive income (loss) before income taxes									(5)	(3)	7
Other comprehensive income (loss), net of income taxes									(5)	(3)	7
Total comprehensive income (loss)									(224)	(5,757)	933
Total comprehensive income (loss) attributable to controlling interest									(224)	(5,757)	933
Subsidiary Issuer
Condensed Consolidating Financial Information
Operating revenues									5
Cost and expenses									16	4	3
Operating income (loss)									(11)	(4)	(3)
Other income (expense), net
Interest expense, net									(576)	(510)	(494)
Equity in earnings									402	(5,174)	1,484
Other, net									(4)	9	(7)
Total other income (expense), net									(178)	(5,675)	983
Income (loss) from continuing operations before income tax expense									(189)	(5,679)	980
Income (loss) from continuing operations									(189)	(5,679)	980
Net income (loss)									(189)	(5,679)	980
Net income (loss) attributable to controlling interest									(189)	(5,679)	980
Other comprehensive income (loss) before income taxes									(31)	(114)	(44)
Other comprehensive income (loss), net of income taxes									(31)	(114)	(44)
Total comprehensive income (loss)									(220)	(5,793)	936
Total comprehensive income (loss) attributable to controlling interest									(220)	(5,793)	936
Other Subsidiaries
Condensed Consolidating Financial Information
Operating revenues									9,213	8,045	7,964
Cost and expenses									7,463	7,546	5,441
Loss on impairment									(140)	(5,201)
Gain (loss) on disposal of assets, net									36	(12)	255
Operating income (loss)									1,646	(4,714)	2,778
Other income (expense), net
Interest expense, net									(79)	(56)	(51)
Other, net									(44)	(108)	(24)
Total other income (expense), net									(123)	(164)	(75)
Income (loss) from continuing operations before income tax expense									1,523	(4,878)	2,703
Income tax expense									50	324	292
Income (loss) from continuing operations									1,473	(5,202)	2,411
Income (loss) from discontinued operations, net of tax									(1,027)	85	(894)
Net income (loss)									446	(5,117)	1,517
Net income (loss) attributable to noncontrolling interest									8	77	43
Net income (loss) attributable to controlling interest									438	(5,194)	1,474
Other comprehensive income (loss) before income taxes									35	(64)	28
Income taxes related to other comprehensive income (loss)									(7)	13	(9)
Other comprehensive income (loss), net of income taxes									28	(51)	19
Total comprehensive income (loss)									474	(5,168)	1,536
Total comprehensive income (loss) attributable to noncontrolling interest									8	73	22
Total comprehensive income (loss) attributable to controlling interest									466	(5,241)	1,514
Consolidating adjustments
Condensed Consolidating Financial Information
Operating revenues									(22)	(18)	(15)
Cost and expenses									(22)	(18)	(15)
Other income (expense), net
Equity in earnings									(249)	10,873	(2,454)
Total other income (expense), net									(249)	10,873	(2,454)
Income (loss) from continuing operations before income tax expense									(249)	10,873	(2,454)
Income (loss) from continuing operations									(249)	10,873	(2,454)
Net income (loss)									(249)	10,873	(2,454)
Net income (loss) attributable to controlling interest									(249)	10,873	(2,454)
Total comprehensive income (loss)									(249)	10,873	(2,454)
Total comprehensive income (loss) attributable to controlling interest									$ (249)	$ 10,873	$ (2,454)

Condensed Consolidating Financial Information (Details 2) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Assets
Cash and cash equivalents	$ 5,134	$ 4,017	$ 3,354	$ 1,130
Other current assets	3,513	3,519
Total current assets	8,647	7,536	6,209
Property and equipment, net	20,880	20,788	19,119
Goodwill	2,987	3,217	8,132
Investment in affiliates	196
Other assets	1,545	3,491	3,354
Total assets	34,255	35,032	36,814
Liabilities and equity
Debt due within one year	1,367	2,187
Other current liabilities	4,096	3,341
Total current liabilities	5,463	5,528	3,996
Long-term debt	11,092	11,349
Other long-term liabilities	1,970	2,412
Total long-term liabilities	13,062	13,761	11,437
Commitments and contingencies
Redeemable noncontrolling interest		116	41
Total equity	15,730	15,627	21,340	20,559
Total liabilities and equity	34,255	35,032	36,814
Parent Guarantor
Assets
Cash and cash equivalents	24	3	38	5
Other current assets	7	8
Total current assets	31	11
Property and equipment, net		1
Investment in affiliates	16,354	16,439
Total assets	16,385	16,451
Liabilities and equity
Other current liabilities	13	294
Total current liabilities	13	294
Long-term debt	594	495
Other long-term liabilities	33	25
Total long-term liabilities	627	520
Commitments and contingencies
Total equity	15,745	15,637
Total liabilities and equity	16,385	16,451
Subsidiary Issuer
Assets
Cash and cash equivalents	3,155	2,793	2,041	117
Other current assets	1,901	784
Total current assets	5,056	3,577
Investment in affiliates	27,933	27,518
Other assets	1,804	1,368
Total assets	34,793	32,463
Liabilities and equity
Debt due within one year	564	1,693
Other current liabilities	632	367
Total current liabilities	1,196	2,060
Long-term debt	17,772	14,308
Other long-term liabilities	454	439
Total long-term liabilities	18,226	14,747
Commitments and contingencies
Total equity	15,371	15,656
Total liabilities and equity	34,793	32,463
Other Subsidiaries
Assets
Cash and cash equivalents	1,955	1,221	1,275	1,008
Other current assets	3,852	4,476
Total current assets	5,807	5,697
Property and equipment, net	20,880	20,787
Goodwill	2,987	3,217
Investment in affiliates	196
Other assets	18,048	20,799
Total assets	47,918	50,500
Liabilities and equity
Debt due within one year	803	494
Other current liabilities	5,698	4,429
Total current liabilities	6,501	4,923
Long-term debt	11,033	15,222
Other long-term liabilities	1,483	1,948
Total long-term liabilities	12,516	17,170
Commitments and contingencies
Redeemable noncontrolling interest		116
Total equity	28,901	28,291
Total liabilities and equity	47,918	50,500
Consolidating adjustments
Assets
Other current assets	(2,247)	(1,749)
Total current assets	(2,247)	(1,749)
Investment in affiliates	(44,287)	(43,957)
Other assets	(18,307)	(18,676)
Total assets	(64,841)	(64,382)
Liabilities and equity
Other current liabilities	(2,247)	(1,749)
Total current liabilities	(2,247)	(1,749)
Long-term debt	(18,307)	(18,676)
Total long-term liabilities	(18,307)	(18,676)
Commitments and contingencies
Total equity	(44,287)	(43,957)
Total liabilities and equity	$ (64,841)	$ (64,382)

Condensed Consolidating Financial Information (Details 3) (USD $) In Millions, unless otherwise specified	1 Months Ended		12 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Condensed Consolidating Financial Information
Cash flows from operating activities			$ 2,708	$ 1,825	$ 3,906
Cash flows from investing activities
Capital expenditures			(1,303)	(974)	(1,349)
Capital expenditures for discontinued operations			(106)	(46)	(42)
Investment in business combination, net of cash acquired				(1,246)
Proceeds from insurance recoveries for loss of drilling unit					560
Proceeds from disposal of assets, net			191	14	60
Proceeds from disposal of discontinued operations, net			789	447
Other, net			40	(91)	50
Net cash used in investing activities			(389)	(1,896)	(721)
Cash flows from financing activities
Changes in short-term borrowings, net			(260)	(88)	(193)
Proceeds from debt			1,493	2,939	2,054
Repayments of debt			(2,282)	(2,409)	(2,565)
Proceeds from restricted cash investments			311	479
Deposits to restricted cash investments			(167)	(523)
Proceeds from share issuance		1,200		1,211
Distribution of qualifying additional paid-in capital	(278)		(278)	(763)
Purchases of shares held in treasury					(240)
Other, net			(19)	(112)	(17)
Net cash provided by (used in) financing activities			(1,202)	734	(961)
Net increase in cash and cash equivalents			1,117	663	2,224
Cash and cash equivalents at beginning of period			4,017	3,354	1,130
Cash and cash equivalents at end of period		4,017	5,134	4,017	3,354
Parent Guarantor
Condensed Consolidating Financial Information
Cash flows from operating activities			(86)	(52)	(33)
Cash flows from investing activities
Capital expenditures					(4)
Investing activities with affiliates, net			(165)	(875)	310
Net cash used in investing activities			(165)	(875)	306
Cash flows from financing activities
Proceeds from debt				435
Repayments of debt				(429)
Proceeds from restricted cash investments				429
Deposits to restricted cash investments				(435)
Proceeds from share issuance				1,211
Distribution of qualifying additional paid-in capital			(278)	(763)
Purchases of shares held in treasury					(240)
Financing activities with affiliates, net			549	495
Other, net			1	(51)
Net cash provided by (used in) financing activities			272	892	(240)
Net increase in cash and cash equivalents			21	(35)	33
Cash and cash equivalents at beginning of period			3	38	5
Cash and cash equivalents at end of period		3	24	3	38
Subsidiary Issuer
Condensed Consolidating Financial Information
Cash flows from operating activities			(953)	(568)	(358)
Cash flows from investing activities
Proceeds from disposal of discontinued operations, net			568
Investing activities with affiliates, net			(2,344)	(325)	1,357
Other, net			29	(23)	(6)
Net cash used in investing activities			(1,747)	(348)	1,351
Cash flows from financing activities
Changes in short-term borrowings, net				(88)	(193)
Proceeds from debt			1,493	2,504	1,999
Repayments of debt			(1,689)	(1,827)	(2,245)
Financing activities with affiliates, net			3,276	1,114	1,384
Other, net			(18)	(35)	(14)
Net cash provided by (used in) financing activities			3,062	1,668	931
Net increase in cash and cash equivalents			362	752	1,924
Cash and cash equivalents at beginning of period			2,793	2,041	117
Cash and cash equivalents at end of period		2,793	3,155	2,793	2,041
Other Subsidiaries
Condensed Consolidating Financial Information
Cash flows from operating activities			3,747	2,445	4,297
Cash flows from investing activities
Capital expenditures			(1,303)	(974)	(1,345)
Capital expenditures for discontinued operations			(106)	(46)	(42)
Investment in business combination, net of cash acquired				(1,246)
Proceeds from insurance recoveries for loss of drilling unit					560
Proceeds from disposal of assets, net			191	14	60
Proceeds from disposal of discontinued operations, net			221	447
Investing activities with affiliates, net			(3,726)	(1,764)	(1,694)
Other, net			11	(68)	56
Net cash used in investing activities			(4,712)	(3,637)	(2,405)
Cash flows from financing activities
Changes in short-term borrowings, net			(260)
Proceeds from debt					55
Repayments of debt			(593)	(153)	(320)
Proceeds from restricted cash investments			311	50
Deposits to restricted cash investments			(167)	(88)
Financing activities with affiliates, net			2,410	1,355	(1,357)
Other, net			(2)	(26)	(3)
Net cash provided by (used in) financing activities			1,699	1,138	(1,625)
Net increase in cash and cash equivalents			734	(54)	267
Cash and cash equivalents at beginning of period			1,221	1,275	1,008
Cash and cash equivalents at end of period		1,221	1,955	1,221	1,275
Consolidating adjustments
Cash flows from investing activities
Investing activities with affiliates, net			6,235	2,964	27
Net cash used in investing activities			6,235	2,964	27
Cash flows from financing activities
Financing activities with affiliates, net			(6,235)	(2,964)	(27)
Net cash provided by (used in) financing activities			$ (6,235)	$ (2,964)	$ (27)

Related Party Transactions (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended
	May 31, 2012	Aug. 31, 2012	Feb. 29, 2012	May 29, 2012 TPDI	Oct. 18, 2007 TPDI	Oct. 18, 2007 Quantum Pacific Management Limited item
Related Party Transactions
Number of Ultra-Deepwater Floaters						2
Ownership interest in affiliate (as a percent)					50.00%
Ownership interest in unconsolidated joint venture (as a percent)			50.00%	50.00%
Issuance of shares in exchange for redeemable noncontrolling interest (in shares)	8.7
Final Cash Settlement for Noncontrolling Interest		$ 72
Percentage of TPDI's working capital	50.00%

Quarterly Results (Unaudited) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Quarterly Results (Unaudited)
Operating revenues	$ 2,326	$ 2,431	$ 2,329	$ 2,110	$ 2,133	$ 1,974	$ 2,051	$ 1,869	$ 9,196	$ 8,027	$ 7,949
Operating income (loss)	541	811	(142)	371	(5,811)	303	380	366	1,581	(4,762)	2,730
Income (loss) from continuing operations	432	533	(303)	154	(6,094)	(19)	171	180	816	(5,762)	1,863
Net income (loss) attributable to controlling interest	456	(381)	(304)	10	(6,165)	(32)	124	319	(219)	(5,754)	926
Per share earnings (loss) from continuing operations
Basic (in dollars per share)	$ 1.19	$ 1.49	$ (0.86)	$ 0.42	$ (18.67)	$ (0.09)	$ 0.51	$ 0.51	$ (0.62)	$ (17.88)	$ 2.88
Diluted (in dollars per share)	$ 1.19	$ 1.49	$ (0.86)	$ 0.42	$ (18.67)	$ (0.09)	$ 0.50	$ 0.51	$ (0.62)	$ (17.88)	$ 2.88
Weighted-average shares outstanding
Basic: (in shares)	359	359	353	350	329	320	320	319	356	322	320
Diluted: (in shares)	360	359	353	350	329	320	320	320	356	322	320
Impairment					5,200				118	5,200
Loss recognized during the period						78
Loss associated with the Macondo well incident contingencies			750		1,000
Gains (losses) on disposal of discontinued operations	12	(1)	72	(1)	8	(1)	(2)	178
Impairment of intangible asset associated with the U.K. operations of drilling management services reporting unit									$ (22)

Subsequent Events (Details)					1 Months Ended	12 Months Ended	0 Months Ended						12 Months Ended
Subsequent Events (Details)	Dec. 31, 2012 USD ($)	Dec. 31, 2012 NOK	Dec. 31, 2012 Macondo well incident USD ($)	Dec. 31, 2011 Macondo well incident USD ($)	Jun. 30, 2010 Macondo well incident Shareholder derivative claims item	Dec. 31, 2011 Macondo well incident Shareholder derivative claims lawsuit plaintiff	Feb. 19, 2012 Brazil Frade field incident item	Dec. 31, 2012 FRN Callable Bonds USD ($)	Dec. 31, 2012 FRN Callable Bonds NOK	Dec. 31, 2012 11% Callable Bonds USD ($)	Dec. 31, 2012 11% Callable Bonds NOK	Dec. 31, 2012 5% Notes due February 2013	Dec. 31, 2012 Subsequent Events	Dec. 31, 2012 Subsequent Events Plea agreement Less than 60 day sentencing USD ($)	Dec. 31, 2012 Subsequent Events Consent Decree USD ($)	Dec. 31, 2012 Subsequent Events Consent Decree Less than 60 day sentencing USD ($)	Dec. 31, 2012 Subsequent Events Consent Decree Less than one year sentencing USD ($)	Dec. 31, 2012 Subsequent Events Consent Decree Less than two year sentencing USD ($)	Dec. 31, 2012 Subsequent Events Macondo well incident USD ($)	Dec. 31, 2012 Subsequent Events National Fish & Wildlife Foundation Plea agreement USD ($)	Dec. 31, 2012 Subsequent Events National Fish & Wildlife Foundation Plea agreement Less than 60 day sentencing USD ($)	Dec. 31, 2012 Subsequent Events National Fish & Wildlife Foundation Plea agreement Less than one year sentencing USD ($)	Dec. 31, 2012 Subsequent Events National Fish & Wildlife Foundation Plea agreement Less than two year sentencing USD ($)	Dec. 31, 2012 Subsequent Events National Academy of Sciences Plea agreement USD ($)	Dec. 31, 2012 Subsequent Events National Academy of Sciences Plea agreement Less than 90 day sentencing USD ($)	Dec. 31, 2012 Subsequent Events National Academy of Sciences Plea agreement Less than one year sentencing USD ($)	Dec. 31, 2012 Subsequent Events National Academy of Sciences Plea agreement Less than two year sentencing USD ($)	Dec. 31, 2012 Subsequent Events National Academy of Sciences Plea agreement Less than three year sentencing USD ($)	Dec. 31, 2012 Subsequent Events National Academy of Sciences Plea agreement Less than four year sentencing USD ($)	Dec. 31, 2012 Subsequent Events Series C Convertible Senior Notes USD ($)	Dec. 31, 2012 Jackups D.R. Stewart and GSF Adriatic VIII USD ($)	Dec. 31, 2012 Debt 5% Notes due February 2013 USD ($)
Subsequent Events
Carrying value of drilling fleet assets reclassified to assets held for sale																															$ 45,000,000
Aggregate cash payment made for debt repurchased																														62,000,000
Principal amount	12,437,000,000							169,000,000		101,000,000																						250,000,000
Interest rate on convertible debt not having effect on earning per share calculation (as a percent)								11.00%	11.00%	11.00%	11.00%	5.00%
Debt instrument face amount									940,000,000		560,000,000
NOK exchange rate		5.56
Contingencies
Amount paid fines, recoveries and civil penalties			1,900,000,000	1,200,000,000															1,400,000,000
Period of schedule payment																			5 years
Amount of Plea Agreement criminal fine														100,000,000
Amount of required payment																				150,000,000	58,000,000	53,000,000	39,000,000	150,000,000	2,000,000	7,000,000	21,000,000	60,000,000	60,000,000
Probation period													5 years
Amount of civil penalty excluding interest															$ 1,000,000,000	$ 400,000,000	$ 400,000,000	$ 200,000,000
Plea Agreement required payment must be paid within the period of sentencing																					60 days	1 year	2 years		90 days	1 year	2 years	3 years	60 days
Plea Agreement criminal fine must be paid within the period of sentencing														60 days
Amount of civil penatly must be paid within the period of sentencing																60 days	1 year	2 years
Period for calculating statutory post-judgment interest rate													1 year
Additional interest rate													2.00%
Performance plan approval period													120 days
Term of EPA Agreement													5 years
Minimum period for complied terms and provisions													12 months
Number of employees							5
Number of actions or claims that were pending					2	2
Number of shareholders who filed suites naming company as nominal defendant						1

Schedule II - Valuation and Qualifying Accounts (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Allowance for doubtful accounts receivable
Reserves and allowances deducted from asset accounts
Balance at the beginning of the period	$ 28,000,000	$ 38,000,000	$ 65,000,000
Charge to cost and expenses			5,000,000
Deductions	8,000,000	10,000,000	32,000,000
Balance at the end of the period	20,000,000	28,000,000	38,000,000
Allowance for obsolete materials and supplies
Reserves and allowances deducted from asset accounts
Balance at the beginning of the period	73,000,000	70,000,000	66,000,000
Charge to cost and expenses	8,000,000	5,000,000	6,000,000
Deductions	15,000,000	2,000,000	2,000,000
Balance at the end of the period	66,000,000	73,000,000	70,000,000
Deductions resulting from sale of rigs and inventory			1,000,000
Deductions resulting from loss of Deepwater Horizon			1,000,000
Valuation allowance on deferred tax assets
Reserves and allowances deducted from asset accounts
Balance at the beginning of the period	183,000,000	164,000,000	160,000,000
Charge to cost and expenses	28,000,000	19,000,000	8,000,000
Deductions	1,000,000		4,000,000
Balance at the end of the period	$ 210,000,000	$ 183,000,000	$ 164,000,000

Quarterly Results (Unaudited) (Details 2) (Sell of Discoverer 534 and Jim Cunningham, USD $) In Millions, unless otherwise specified	3 Months Ended
	Sep. 30, 2012
Sell of Discoverer 534 and Jim Cunningham
Quarterly results
Gain (loss) on the sale of assets	$ 51