Document and Entity Information (USD $) In Billions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Feb. 22, 2012	Jun. 30, 2011
Document and Entity Information
Entity Registrant Name	Transocean Ltd.
Entity Central Index Key	0001451505
Document Type	10-K
Document Period End Date	Dec. 31, 2011
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			$ 20.6
Entity Common Stock, Shares Outstanding		350,424,694
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	FY

CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Operating revenues
Contract drilling revenues	$ 8,335	$ 8,888	$ 10,522
Contract drilling intangible revenues	45	98	281
Other revenues	762	480	638
Total operating revenues	9,142	9,466	11,441
Costs and expenses
Operating and maintenance	6,956	5,074	5,066
Depreciation and amortization	1,449	1,536	1,433
General and administrative	288	246	209
Total costs and expenses	8,693	6,856	6,708
Loss on impairment	(5,229)	(1,010)	(334)
Gain (loss) on disposal of assets, net	4	257	(9)
Operating income (loss)	(4,776)	1,857	4,390
Other income (expense), net
Interest income	44	23	5
Interest expense, net of amounts capitalized	(621)	(567)	(484)
Loss on retirement of debt		(33)	(29)
Other, net	(81)	10	37
Total other income (expense), net	(658)	(567)	(471)
Income (loss) from continuing operations before income tax expense	(5,434)	1,290	3,919
Income tax expense	395	336	723
Income (loss) from continuing operations	(5,829)	954	3,196
Income (loss) from discontinued operations, net of tax	197	34	(26)
Net income (loss)	(5,632)	988	3,170
Net income (loss) attributable to noncontrolling interest	93	27	(11)
Net income (loss) attributable to controlling interest	$ (5,725)	$ 961	$ 3,181
Earnings per share-basic
Earnings (loss) from continuing operations (in dollars per share)	$ (18.40)	$ 2.88	$ 9.95
Earnings (loss) from discontinued operations (in dollars per share)	$ 0.61	$ 0.11	$ (0.08)
Earnings (loss) per share (in dollars per share)	$ (17.79)	$ 2.99	$ 9.87
Earnings per share-diluted
Earnings (loss) from continuing operations (in dollars per share)	$ (18.40)	$ 2.88	$ 9.92
Earnings (loss) from discontinued operations (in dollars per share)	$ 0.61	$ 0.11	$ (0.08)
Earnings (loss) per share (in dollars per share)	$ (17.79)	$ 2.99	$ 9.84
Weighted-average shares outstanding
Basic (in shares)	322	320	320
Diluted (in shares)	322	320	321

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Net income (loss)	$ (5,632)	$ 988	$ 3,170
Other comprehensive income (loss) before income taxes
Unrecognized components of net periodic benefit costs	(204)	(8)	37
Unrecognized loss on derivative instruments	(13)	(29)	(2)
Unrecognized loss on marketable securities	(13)
Recognized components of net periodic benefit costs	25	16	24
Recognized loss on derivative instruments	11	12	6
Recognized loss on marketable securities	13		1
Other comprehensive income (loss) before income taxes	(181)	(9)	66
Income taxes related to other comprehensive income (loss)	13	(9)	24
Other comprehensive income (loss), net of income taxes	(168)	(18)	90
Total comprehensive income (loss)	(5,800)	970	3,260
Total comprehensive income (loss) attributable to noncontrolling interest	89	6	(6)
Total comprehensive income (loss) attributable to controlling interest	$ (5,889)	$ 964	$ 3,266

CONSOLIDATED BALANCE SHEETS (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Assets
Cash and cash equivalents	$ 4,017	$ 3,394
Accounts receivable, net
Trade	2,049	1,653
Other	127	190
Materials and supplies, net	627	514
Deferred income taxes, net	142	115
Assets held for sale	26
Other current assets	621	329
Total current assets	7,609	6,195
Property and equipment	29,037	26,721
Property and equipment of consolidated variable interest entities	2,252	2,214
Less accumulated depreciation	8,760	7,616
Property and equipment, net	22,529	21,319
Goodwill	3,205	8,132
Other assets	1,745	1,165
Total assets	35,088	36,811
Liabilities and equity
Accounts payable	880	832
Accrued income taxes	89	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	2,350	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	523	575
Other long-term liabilities	1,903	1,791
Total long-term liabilities	13,923	11,575
Commitments and contingencies
Redeemable noncontrolling interest	116	25
Shares, CHF 15.00 par value, 365,135,298 authorized, 167,617,649 conditionally authorized, 365,135,298 issued and 349,805,793 outstanding at December 31, 2011; and 335,235,298 authorized, 167,617,649 conditionally authorized, 335,235,298 issued and 319,080,678 outstanding at December 31, 2010	4,982	4,482
Additional paid-in capital	7,211	7,504
Treasury shares, at cost, 2,863,267 held at December 31, 2011 and 2010	(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

CONSOLIDATED BALANCE SHEETS (Parenthetical) (CHF)	Dec. 31, 2011	Dec. 31, 2010
CONSOLIDATED BALANCE SHEETS
Shares, CHF par value (in Swiss francs per share)	15.00	15.00
Shares, authorized	365,135,298	335,235,298
Shares, conditionally authorized	167,617,649	167,617,649
Shares, issued	365,135,298	335,235,298
Shares, outstanding	349,805,793	319,080,678
Treasury shares	2,863,267	2,863,267

CONSOLIDATED STATEMENTS OF EQUITY In Millions, except Share data, 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, 2008	$ 17,167		$ 17,164	$ 4,444	$ 7,313		$ 5,827	$ (420)	$ 3
Balance (in shares) at Dec. 31, 2008				319,000,000
Increase (Decrease) in Shareholders' Equity
Share-based compensation	81		81		81
Issuance of shares under share-based compensation plans	35		35	28	7
Issuance of shares under share-based compensation plans				2,000,000
Net income (loss) attributable to controlling interest	3,181						3,181
Other comprehensive income (loss) attributable to controlling interest								85
Total comprehensive income attributable to controlling interest	3,266		3,266
Total comprehensive income (loss) attributable to noncontrolling interest	(6)								(6)
Total comprehensive income (loss)	3,260
Other, net	16		6		6				10
Balance at Dec. 31, 2009	20,559		20,552	4,472	7,407		9,008	(335)	7
Balance (in shares) at Dec. 31, 2009				321,000,000
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				1,000,000
Purchases of shares held in treasury	(240)	(257)	(240)			(240)
Purchases of shares held in treasury (in shares)	(2,863,267)			(3,000,000)
Net income (loss) attributable to controlling interest	961						961
Other comprehensive income (loss) attributable to controlling interest								3
Total comprehensive income attributable to controlling interest	964		964
Total comprehensive income (loss) attributable to noncontrolling interest	6								7
Reclassification of redeemable noncontrolling interest	26								(26)
Total comprehensive income (loss)	971
Other, net	(16)		6		6				4
Balance at Dec. 31, 2010	21,375		21,383	4,482	7,504	(240)	9,969	(332)	(8)
Balance (in shares) at Dec. 31, 2010				319,000,000
Increase (Decrease) in Shareholders' Equity
Issuance of shares, net of issue costs	1,159		1,159	488	671
Issuance of shares (in shares)				30,000,000
Share-based compensation	95		95		95
Issuance of shares under share-based compensation plans	(6)		(6)	12	(18)
Issuance of shares under share-based compensation plans				1,000,000
Obligation for distribution of qualifying additional paid-in capital	(1,041)		(1,041)		(1,041)
Net income (loss) attributable to controlling interest	(5,725)						(5,725)
Other comprehensive income (loss) attributable to controlling interest								(164)
Total comprehensive income attributable to controlling interest	(5,889)		(5,889)
Total comprehensive income (loss) attributable to noncontrolling interest	89								(2)
Total comprehensive income (loss)	(5,891)
Balance at Dec. 31, 2011	$ 15,691		$ 15,701	$ 4,982	$ 7,211	$ (240)	$ 4,244	$ (496)	$ (10)
Balance (in shares) at Dec. 31, 2011				350,000,000

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Cash flows from operating activities
Net income (loss)	$ (5,632)	$ 988	$ 3,170
Adjustments to reconcile to net cash provided by operating activities:
Amortization of drilling contract intangibles	(45)	(98)	(281)
Depreciation and amortization	1,449	1,536	1,433
Share-based compensation expense	95	102	81
Loss on impairment	5,229	1,010	334
(Gain) loss on disposal of assets, net	(4)	(257)	9
Gain on disposal of discontinued operations, net	(181)
Amortization of debt issue costs, discounts and premiums, net	125	189	209
Deferred income taxes	(31)	(114)	(15)
Other, net	112	55	93
Changes in deferred revenue, net	(16)	205	169
Changes in deferred expenses, net	(61)	(79)	(38)
Changes in operating assets and liabilities	745	409	434
Net cash provided by operating activities	1,785	3,946	5,598
Cash flows from investing activities
Capital expenditures	(1,020)	(1,391)	(3,041)
Investment in business combination, net of cash acquired	(1,246)
Payment for settlement of forward exchange contract, net	(78)
Purchases of marketable securities			(269)
Proceeds from disposal of assets, net	177	60	18
Proceeds from disposal of discontinued operations, net	284
Proceeds from insurance recoveries for loss of drilling unit		560
Proceeds from sale of marketable securities		37	564
Other, net	(13)	13	34
Net cash used in investing activities	(1,896)	(721)	(2,694)
Cash flows from financing activities
Changes in short-term borrowings, net	(88)	(193)	(382)
Proceeds from debt	2,939	2,054	514
Repayments of debt	(2,409)	(2,565)	(2,871)
Proceeds from restricted cash investments	479
Deposits to restricted cash investments	(523)
Proceeds from share issuance	1,211
Distribution of qualifying additional paid-in capital	(763)
Purchases of shares held in treasury		(240)
Financing costs	(83)	(15)	(2)
Other, net	(29)	(2)	4
Net cash provided by (used in) financing activities	734	(961)	(2,737)
Net increase in cash and cash equivalents	623	2,264	167
Cash and cash equivalents at beginning of period	3,394	1,130	963
Cash and cash equivalents at end of period	$ 4,017	$ 3,394	$ 1,130

Nature of Business

12 Months Ended

Dec. 31, 2011

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, 2011, we owned or had partial ownership interests in and operated 135 mobile offshore drilling units. As of this date, our fleet consisted of 50 High-Specification Floaters (Ultra-Deepwater, Deepwater and Harsh Environment semisubmersibles and drillships), 25 Midwater Floaters, nine High-Specification Jackups, 50 Standard Jackups and one swamp barge. In addition, we had two Ultra-Deepwater Floaters and four High-Specification Jackups under construction (see Note 10—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 U.K. subsidiaries (together, “ADTI”). ADTI conducts drilling management services primarily on either a dayrate or a completed-project, fixed-price (or “turnkey”) basis.

In February 2011, we sold the subsidiary that owns the High-Specification Jackup Trident 20, located in the Caspian Sea. In March 2011, we engaged an unaffiliated advisor to coordinate the sale of the assets of our oil and gas properties reporting unit, a component of our other operations segment, which comprises the exploration, development and production activities performed by Challenger Minerals Inc. and Challenger Minerals (North Sea) Limited (together, “CMI”). As a result of these actions, we reclassified to discontinued operations the operating results associated with our Caspian Sea operations and our oil and gas operations. Additionally, we reclassified the assets and liabilities of these components as held for sale. In October 2011, we completed the sale of Challenger Minerals (North Sea) Limited. See Note 7—Discontinued Operations and Note 28—Subsequent Events.

In October 2011, we completed our acquisition of Aker Drilling, a Norwegian company formerly listed on the Oslo Stock Exchange. In connection with the acquisition, we acquired two Harsh Environment, Ultra-Deepwater semisubmersibles currently operating on long-term contracts in Norway. Additionally, we acquired two Ultra-Deepwater drillships currently under construction at the Daewoo Shipbuilding & Marine Engineering Co. Ltd. shipyard in Korea, which have expected deliveries in 2014. See Note 4—Business Combination.

Significant Accounting Policies

12 Months Ended

Dec. 31, 2011

Significant Accounting Policies

Significant Accounting Policies

Note 2—Significant Accounting Policies

Accounting estimates—The preparation of financial statements in accordance with accounting principles generally accepted in the United States (“U.S.”) requires us 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 allowance for doubtful accounts, materials and supplies obsolescence, property and equipment, investments, notes receivable, goodwill and other intangible assets, income taxes, share-based compensation, defined benefit pension plans and other postretirement benefits and contingencies. 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 significant 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 investments in entities if we have the ability to exercise significant influence over an 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 investments in other entities if we do not have the ability to exercise significant influence over the unconsolidated affiliate. See Note 23—Variable Interest Entities.

We recognized equity in earnings of unconsolidated affiliates, recorded in other, net, on our consolidated statements of operations, in the amount of $18 million, $8 million and $6 million for the years ended December 31, 2011, 2010 and 2009, respectively. Our investments in and advances to unconsolidated affiliates, recorded in other assets, had carrying amounts of less than $1 million and $19 million at December 31, 2011 and 2010, respectively.

Business combination—In connection with our acquisition of 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, and our estimates are subject to adjustment based on our final assessments of the fair values of property and equipment, intangible assets, liabilities and our evaluation of tax positions and contingencies. We will complete our final assessments of the fair values of the acquired assets and assumed liabilities and our final evaluations of uncertain tax positions and contingencies within one year of the acquisition date. See Note 4—Business Combination.

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.

Contract drilling intangible revenues—In connection with our business combination with GlobalSantaFe Corporation in November 2007, we acquired drilling contracts for future contract drilling services. The terms of these contracts include all 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. We recognized contract drilling intangible revenues of $45 million, $98 million and $281 million in the years ended December 31, 2011, 2010 and 2009, respectively. See Note 11—Goodwill and Other Intangible Assets.

Other revenues—Our other revenues represent those derived from drilling management services, integrated 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 anticipated. We refer to integrated services as those services we provide through contractors and our employees under certain contracts that include well and logistics services in addition to our normal drilling services. 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. Share-based compensation expense is recognized, net of a forfeiture rate, estimated at the time of grant based on historical experience and adjusted, if necessary, in subsequent periods based on actual forfeitures.

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 (“SARs”) 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 model and an average price at the performance start date. The risk neutral model 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. Share-based compensation expense was $95 million, $102 million and $81 million in the years ended December 31, 2011, 2010 and 2009, respectively. Income tax benefit on share-based compensation expense was $16 million, $13 million, and $11 million in the years ended December 31, 2011, 2010 and 2009, respectively. See Note 18—Share-Based Compensation Plans.

Capitalized interest—We capitalize interest costs for qualifying construction and upgrade projects. We capitalized interest costs on construction work in progress of $39 million, $89 million and $182 million for the years ended December 31, 2011, 2010 and 2009, 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 income (expense), net. We recognized net foreign currency exchange gain (losses) of $(99) million, $1 million and $(33) million for the years ended December 31, 2011, 2010 and 2009, respectively. See Note 13—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 (“NOL”) 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 6—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, 2011, the aggregate carrying amount of our restricted cash investments was $928 million, of which $182 million and $746 million was classified in other current assets and other assets, respectively. At December 31, 2010, the aggregate carrying amount of our restricted cash investments was $47 million, classified in other assets. See Note 12—Debt.

Allowance for doubtful accounts—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 is unlikely to occur. 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. The allowance for doubtful accounts was $28 million and $38 million at December 31, 2011 and 2010, respectively.

Materials and supplies—Materials and supplies are carried at average cost less an allowance for obsolescence. The allowance for obsolescence was $73 million and $70 million at December 31, 2011 and 2010, 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. Assets held for sale were $26 million and less than $1 million at December 31, 2011 and 2010, respectively. See Note 7—Discontinued Operations.

Property and equipment—Property and equipment, consisting primarily of offshore drilling rigs and related equipment, represented approximately 64 percent of our total assets at December 31, 2011. The carrying amounts of these assets are based on 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. 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 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 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. During 2009, we adjusted the useful lives for 10 rigs, extending the estimated useful lives from between 30 and 35 years to between 33 and 50 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. For each of the years ended December 31, 2011, 2010 and 2009, the changes in estimated useful lives of these rigs resulted in a reduction in depreciation expense of $2 million ($0.01 per diluted share from continuing operations), $23 million ($0.07 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 and a drilling management services customer relationships intangible asset, 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, High-Specification Jackups, and Standard 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 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 fair value less cost to sell.

In the year ended December 31, 2011, we concluded that our assets held for sale were impaired, and we recognized a loss on impairment of $28 million. In the year ended December 31, 2010, we concluded that our Standard Jackup asset group was impaired, and we recognized a loss on impairment of $1.0 billion ($3.15 per diluted share from continuing operations), which had no tax effect. In the year ended December 31, 2009, we determined that our assets held for sale and our customer relationships intangible asset were impaired, and we recognized losses on the impairment of these assets in the amount of $279 million ($0.87 per diluted share from continuing operations), which had no tax effect, and $49 million ($0.15 per diluted share from continuing operations), which had no tax effect. See Note 5—Impairments and Note 11—Goodwill and Other 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. 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 testing on October 1, 2011, we concluded that our goodwill was impaired due to a decline in projected cash flows and market valuations for this reporting unit, and we recognized an estimated loss on impairment of goodwill in the amount of $5.2 billion ($16.15 per diluted share from continuing operations), which had no tax effect. As a result of our annual impairment testing in each of the years ended December 31, 2010 and 2009, we concluded that goodwill was not impaired. See Note 5—Impairments and Note 11—Goodwill and Other Intangible Assets.

For our trade name intangible asset, which we have identified as indefinite-lived, we estimate fair value using the relief from royalty method, which applies the income approach. As a result of our impairment testing in the years ended December 31, 2011 and 2010, we concluded that the trade name intangible asset for our drilling management services reporting unit was not impaired. As a result of impairment testing in the year ended December 31, 2009, we concluded that the trade name intangible asset for our drilling management services reporting unit was impaired, and we recognized a loss on impairment in the amount of $6 million ($0.02 per diluted share from continuing operations), which had no tax effect. See Note 5—Impairments and Note 11—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 13—Derivatives and Hedging and Note 22—Financial Instruments and 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 valuation of assets that reduces year-to-year volatility by recognizing investment gains or losses 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.

The obligations and related costs for our defined benefit pension and other postretirement benefit plans, retiree life insurance and medical benefits, are actuarially determined 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.

Pension and other postretirement benefit plan obligations represented an aggregate liability in the amount of their net underfunded status of $640 million and $469 million, at December 31, 2011 and 2010, respectively. Net periodic benefit costs were $88 million, $91 million and $87 million for the years ended December 31, 2011, 2010 and 2009, respectively. See Note 14—Postemployment Benefit Plans.

Contingent liabilities—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 that we expect 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 statement of financial position, results of operations and cash flows to present our oil and gas operating segment and our Caspian Sea operations as discontinued operations (see Note 7—Discontinued Operations). These 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 28—Subsequent Events.

New Accounting Pronouncements

12 Months Ended

Dec. 31, 2011

New Accounting Pronouncements

New Accounting Pronouncements

Note 3—New Accounting Pronouncements

Recently Issued Accounting Standards

Intangibles-goodwill and other—Effective January 1, 2012, we will adopt 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. We do not expect that our adoption will have a material effect on our consolidated financial statements.

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 the disclosures contained in our balance sheet or notes to consolidated financial statements.

Business Combination

12 Months Ended

Dec. 31, 2011

Business Combination

Business Combination

Note 4—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. During 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 $756 million, and the assumption of current liabilities of $272 million and long-term debt of $1.6 billion. 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 $273 million, which was recorded as goodwill. Certain fair value measurements have not been completed, and the purchase price allocation remains preliminary due to the timing of the acquisition and due to the number of acquired assets and assumed liabilities. We continue to review the estimated fair values of property and equipment, intangible assets, and other assets and liabilities, and to evaluate the assumed tax positions and contingencies.

We have included approximately three months of operating results of Aker Drilling in our consolidated results of operations. Our operating revenues include approximately $100 million of contract drilling revenues associated with the operations of Aker Drilling for the year ended December 31, 2011.

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	$	9,454		$	9,797
Operating income (loss)	(4,628		)	1,975
Income (loss) from continuing operations	(5,806		)	999

Per share earnings (loss) from continuing operations
Basic	$	(18.33	)	$	3.02
Diluted	$	(18.33	)	$	3.02

The pro forma financial information includes various adjustments, primarily related to additional depreciation 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 dates or the results of operations for any future periods.

Impairments

12 Months Ended

Dec. 31, 2011

Impairments

Impairments

Note 5—Impairments

Assets held for sale—During the year ended December 31, 2011, we recognized an aggregate loss of $28 million ($0.09 per diluted share from continuing operations), which had a tax effect of less than $1 million, associated with the impairment of GSF Britannia, George H. Galloway, GSF Labrador, and Searex IV, which were each classified as an asset held for sale at the time of impairment. We measured the impairments as the amount by which the carrying amounts of these rigs and related assets exceeded the estimated fair values less costs to sell the rigs and related assets. We estimated the fair values of the rigs and related assets using significant observable inputs, including binding sale and purchase agreements for the assets.

During the year ended December 31, 2009, we determined that GSF Arctic II and GSF Arctic IV, both classified as assets held for sale, were impaired due to the global economic downturn and pressure on commodity prices, both of which had an adverse effect on our industry. We estimated the fair values of these rigs based on an 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 and considering our undertakings to the Office of Fair Trading in the U.K. (“OFT”) that required the sale of the rigs with certain limitations and in a limited amount of time. We based our estimates on significant unobservable inputs, including non-binding price quotes from unaffiliated parties, considering the then-current market conditions and restrictions imposed by the OFT. For the year ended December 31, 2009, as a result of our evaluation, we recognized a loss on impairment of $279 million ($0.87 per diluted share), which had no tax effect. In the year ended December 31, 2010, we completed the sale of these drilling units. See Note 10—Drilling Fleet.

Assets held and used—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. 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. Our valuation utilized the projection of the future performance of the asset group based on significant unobservable inputs, including assumptions regarding long-term projections for future revenues and costs, dayrates, rig utilization and idle time. As a result, we determined that the carrying amount of the Standard Jackup asset group exceeded its fair value, and we recognized a loss on impairment of long-lived assets in the amount of $1.0 billion ($3.15 per diluted share from continuing operations), which had no tax effect, during the year ended December 31, 2010. We did not have an impairment of our assets held and used in either of the years ended December 31, 2011 or 2009.

Goodwill and other indefinite-lived intangible assets—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, and we recognized our best estimate of the loss on impairment in the amount of $5.2 billion ($16.15 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 valuation required us to project the future performance of the contract drilling services reporting unit based on significant unobservable inputs, including assumptions for future commodity prices, projected demand for our services, rig availability and dayrates. We have not completed the measurement of our goodwill impairment due to the complexities involved in determining the implied fair value of goodwill. Our estimate is, therefore, subject to adjustment. We expect to complete the measurement of our goodwill impairment in the three months ending March 31, 2012. As a result of our annual impairment testing for our contract drilling services reporting unit in the year ended December 31, 2010 and 2009, we concluded that goodwill was not impaired.

During the year ended December 31, 2009, we determined that the trade name intangible asset associated with our drilling management services reporting unit was impaired due to market conditions resulting from the global economic downturn and continued pressure on commodity prices. 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. Our valuation required us to project the future performance of the drilling management services reporting unit based on significant unobservable inputs, including assumptions for future commodity prices, projected demand for our services, rig availability and dayrates. As a result of our valuations in the year ended December 31, 2009, we determined that the carrying amount of the trade name intangible asset exceeded its fair value, and we recognized a loss on impairment of $6 million ($0.02 per diluted share), which had no tax effect. In the years ended December 31, 2011 and 2010, we determined that we did not have an impairment of our trade name intangible asset.

Definite-lived intangible assets—During the year ended December 31, 2009, we determined that the customer relationships intangible asset associated with our drilling management services reporting unit was impaired due to market conditions resulting from the global economic downturn and continued pressure on commodity prices. 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. Our valuation required us to project the future performance of the drilling management services reporting unit based on significant unobservable inputs, including assumptions for future commodity prices, projected demand for our services, rig availability and dayrates. As a result of our valuation in the year ended December 31, 2009, we determined that the carrying amount of the customer relationships intangible asset exceeded its fair value, and we recognized a loss on impairment of $49 million ($0.15 per diluted share from continuing operations), which had no tax effect. We were not required to test our definite-lived intangible assets for impairment in either of the years ended December 31, 2011 or 2010.

Income Taxes

12 Months Ended

Dec. 31, 2011

Income Taxes

Income Taxes

Note 6—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,
	2011			2010			2009
Current tax expense	$	426		$	450		$	738
Deferred tax expense (benefit)	(31		)	(114		)	(15		)
Income tax expense	$	395		$	336		$	723

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,
	2011			2010			2009
Income tax expense at the Swiss federal statutory rate	$	(425	)	$	101		$	307
Taxes on earnings subject to rates greater than the Swiss federal statutory rate	285			107			288
Taxes on impairment loss subject to rates less than the Swiss federal statutory rate	409			79			—
Taxes on asset sales subject to rates less than the Swiss federal statutory rate	(16		)	—			—
Taxes on litigation matters subject to rates less than the Swiss federal statutory rate	78			—			—
Changes in unrecognized tax benefits, net	62			71			135
Change in valuation allowance	19			4			49
Benefit from foreign tax credits	(28		)	(23		)	(49		)
Taxes on asset acquisition costs at rates lower than the Swiss federal statutory rate	8			—			—
Other, net	3			(3		)	(7		)
Income tax expense	$	395		$	336		$	723

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

	December 31,
	2011			2010
Deferred tax assets
Drilling contract intangibles	$	2		$	6
Net operating loss carryforwards	341			184
Tax credit carryforwards	45			29
Accrued payroll expenses not currently deductible	77			72
Deferred income	67			84
Valuation allowance	(183		)	(164		)
Other	81			61
Total deferred tax assets	430			272

Deferred tax liabilities
Depreciation and amortization	(749		)	(680		)
Drilling management services intangibles	(25		)	(26		)
Other	(37		)	(26		)
Total deferred tax liabilities	(811		)	(732		)

Net deferred tax liabilities	$	(381	)	$	(460	)

Our deferred tax assets include U.S. foreign tax credit carryforwards of $45 million, which will expire between 2015 and 2021. Deferred tax assets related to our NOLs were generated in various worldwide tax jurisdictions. The tax effect of our Brazilian NOLs, which do not expire, was $57 million and $62 million at December 31, 2011 and 2010, respectively. In connection with our acquisition of Aker Drilling, we acquired $141 million of Norwegian NOLs, which do not expire.

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

	December 31,
	2011		2010
Valuation allowance for non-current deferred tax assets	$	183	$	164

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, 2011, the amount of indefinitely reinvested earnings was approximately $2.2 billion. If all of these indefinitely reinvested earnings were distributed, we would be subject to estimated taxes of $150 million to $200 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,
	2011			2010			2009
Balance, beginning of period	$	485		$	460		$	372
Additions for current year tax positions	45			46			64
Additions for prior year tax positions	23			9			62
Reductions for prior year tax positions	—			(11		)	(22		)
Settlements	(42		)	(17		)	(3		)
Reductions related to statute of limitation expirations	(2		)	(2		)	(13		)
Balance, end of period	$	509		$	485		$	460

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,
	2011		2010
Unrecognized tax benefits, excluding interest and penalties	$	509	$	485
Interest and penalties	272		235
Unrecognized tax benefits, including interest and penalties	$	781	$	720

For the years ended December 31, 2011, 2010 and 2009, we recognized interest and penalties related to our unrecognized tax benefits, recorded as a component of income tax expense, in the amount of $37 million, $35 million and $51 million, respectively. If recognized, $781 million of our unrecognized tax benefits, including interest and penalties, as of December 31, 2011, 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, 2012 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 2003. For the years ended December 31, 2011, 2010 and 2009, the amount of current tax benefit recognized from the settlement of disputes with tax authorities and from the expiration of statutes of limitations was insignificant.

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 17 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. Accordingly, the trial previously scheduled to be heard in U.S. Tax Court in February 2012 has been cancelled. 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, except a claim regarding transfer pricing for certain charters of drilling rigs between our subsidiaries, resulting in a total proposed adjustment of approximately $50 million, excluding interest. We believe an unfavorable outcome on this assessment with respect to 2005 activities would not result in a material adverse effect on our consolidated statement of financial position, results of operations or cash flows. Although we believe the transfer pricing for these charters is materially correct, we have been unable to reach a resolution with the tax authorities.

In May 2010, we received an assessment from the U.S. tax authorities related to our 2006 and 2007 U.S. federal income tax returns. In July 2010, we filed a protest letter with the U.S. tax authorities responding to this assessment. 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. These two items would result in net adjustments of approximately $278 million of additional taxes, excluding interest. An unfavorable outcome on these adjustments could result in a material adverse effect on our consolidated statement of financial position, results of operations or cash flows. We believe our returns are materially correct as filed, and we intend to continue to vigorously defend against all such claims.

In addition, the May 2010 assessment included adjustments related to a series of restructuring transactions that occurred between 2001 and 2004. These restructuring transactions impacted our basis in our former subsidiary, TODCO, which we disposed of in 2004 and 2005. The authorities are disputing the amount of capital losses that resulted from the disposition of TODCO. We utilized a portion of the capital losses to offset capital gains on our U.S federal income tax returns for 2006 through 2009. The majority of the capital losses were unutilized and expired on December 31, 2009. The adjustments would also impact the amount of certain net operating losses and other carryovers in 2006 and later years. The authorities are also contesting the characterization of certain amounts of income received in 2006 and 2007 as capital gain and thus the availability of the capital gain for offset by the capital loss. These claims with respect to our U.S. federal income tax returns for 2006 through 2009 could result in net tax adjustments of approximately $295 million. An unfavorable outcome on these potential adjustments could result in a material adverse effect on our consolidated statement of financial position, results of operations or cash flows. We believe that our U.S federal income tax returns are materially correct as filed, and we intend to vigorously defend against any potential claims.

The May 2010 assessment also included certain claims with respect to withholding taxes and certain other items resulting in net tax adjustments of approximately $160 million, excluding interest. In addition, the tax authorities assessed penalties associated with the various tax adjustments for the 2006 and 2007 audits in the aggregate amount of approximately $88 million, excluding interest. We believe that our tax returns are materially correct as filed, and we intend to vigorously defend against potential claims.

See Note 28—Subsequent Events.

Norway tax investigations—Norwegian civil tax and criminal authorities are investigating various transactions undertaken by our subsidiaries in 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 (a) approximately $262 million plus interest, related to certain restructuring transactions, (b) approximately $115 million plus interest, related to the migration of a subsidiary that was previously subject to tax in Norway, (c) approximately $69 million plus interest, related to a 2001 dividend payment and (d) approximately $7 million plus interest, related to certain foreign exchange deductions and dividend withholding tax. We have filed or expect to file appeals to these tax assessments. With respect to the tax assessment related to the migration of a subsidiary, we provided a guarantee in the amount of approximately $120 million, plus interest, while this dispute is addressed by the Norwegian courts. Furthermore, we may be required to provide some form of additional financial security, in an amount up to $776 million, including interest and penalties, for these other assessed amounts while these disputes are appealed and addressed by the Norwegian courts. The authorities have indicated that they plan to seek penalties of 60 percent on most but not all matters. For these matters, we believe our returns are materially correct as filed, and we have and will continue to respond to all information requests from the Norwegian authorities. 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 2001, as well as inaccuracies in Norwegian statutory financial statements for the years ended December 31, 1996 through 2001. The criminal trial has been scheduled for December 2012. Two employees of our former external tax advisors were also issued indictments with respect to the disclosures in our tax returns. We believe these charges are without merit and plan to vigorously defend our subsidiaries to the fullest extent. We intend to vigorously contest any assertions by the Norwegian civil and criminal authorities in connection with the various transactions being investigated. In October 2011, the Norwegian authorities issued criminal indictments against a Norwegian tax attorney related to certain of our restructuring transactions and to a 2001 dividend payment. An unfavorable outcome on these Norwegian civil and criminal tax matters could result in a material adverse effect on our consolidated statement of financial position, results of operations or cash flows. However, while we cannot predict or provide assurance as to the final outcome of these proceedings, we do not expect the ultimate resolution of these matters 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. See Note 28—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 $109 million, plus a 75 percent penalty in the amount of $82 million and interest through December 31, 2011 in the amount of $150 million. 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. 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.

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 assessments to have a material adverse effect on our consolidated statement of financial position, results of operations or cash flows.

Discontinued Operations

12 Months Ended

Dec. 31, 2011

Discontinued Operations

Discontinued Operations

Note 7—Discontinued Operations

Oil and gas properties—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, a component of our other operations segment, which comprises the exploration, development and production activities performed by Challenger Minerals Inc. and Challenger Minerals (North Sea) Limited, our wholly owned oil and gas subsidiaries. In October 2011, we completed the sale of Challenger Minerals (North Sea) Limited for aggregate net cash proceeds of $24 million and we recognized a gain on the disposal of the discontinued operations of $12 million. See Note 28—Subsequent Events.

Caspian Sea operations—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 segment, reflects our decision to discontinue operations in the Caspian Sea. As a result of the sale, we received net cash proceeds of $259 million and recognized a gain on the disposal of the discontinued operations of $169 million ($0.52 per diluted share from discontinued operations), which had no tax effect. 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.

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,
	2011			2010			2009
Operating revenues	$	62		$	110		$	115
Costs and expenses	(55		)	(99		)	(110		)
Loss on impairment (a)	(10		)	(2		)	—
Gain on disposal of discontinued operations, net	181			—			—
Income from discontinued operations before income tax expense	178			9			5
Income tax benefit (expense)	19			25			(31		)

Income (loss) from discontinued operations, net of tax	$	197		$	34		$	(26	)

(a) During the year ended December 31, 2011, we recognized a loss on impairment of our oil and gas properties, which were classified as assets held for sale, in the amount of $10 million ($0.03 per diluted share from discontinued operations) 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 unobservable inputs, including non-binding price quotes from unaffiliated parties. During the year ended December 31, 2010, we determined that the goodwill associated with our former oil and gas properties reporting unit was impaired, and we recognized a loss on impairment of the full carrying amount of the goodwill associated with the reporting unit in the amount of $2 million ($0.01 per diluted share from discontinued operations), which had no tax effect.

Assets and liabilities of discontinued operations—As a result of our decision to discontinue the operations of our oil and gas properties reporting unit and the operations of our Caspian Sea subsidiary, we also reclassified the related assets and liabilities of these components of our business to other current assets, other assets, other current liabilities and other long-term liabilities as of December 31, 2010. The carrying amounts of the major classes of assets and liabilities associated with these operations were classified as follows (in millions):

	December 31,
	2011		2010
Assets
Oil and gas properties, net	$	24	$	—
Other related assets	2		—
Assets held for sale	$	26	$	—

Accounts receivable	$	6	$	22
Other assets	25		17
Other current assets	$	31	$	39

Rig and related equipment, net	$	—	$	86
Oil and gas properties, net	—		53
Other assets	$	—	$	139

Liabilities
Accounts payable	$	3	$	15
Other liabilities	14		13
Other current liabilities	$	17	$	28

Asset retirement obligation	$	—	$	9
Deferred taxes	—		19
Other long-term liabilities	$	—	$	28

Earnings (Loss) Per Share

12 Months Ended

Dec. 31, 2011

Earnings (Loss) Per Share

Earnings (Loss) Per Share

Note 8—Earnings (Loss) Per Share

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

	Years ended December 31,
	2011						2010						2009
	Basic			Diluted			Basic			Diluted			Basic			Diluted
Numerator for earnings per share
Income (loss) from continuing operations attributable to controlling interest	$	(5,922	)	$	(5,922	)	$	927		$	927		$	3,207		$	3,207
Undistributed earnings allocable to participating securities	—			—			(5		)	(5		)	(18		)	(18		)
Income (loss) from continuing operations available to shareholders	$	(5,922	)	$	(5,922	)	$	922		$	922		$	3,189		$	3,189

Denominator for earnings per share
Weighted-average shares outstanding	322			322			320			320			320			320
Effect of stock options and other share-based awards	—			—			—			—			—			1
Weighted-average shares for per share calculation	322			322			320			320			320			321

Per share earnings (loss) from continuing operations	$	(18.40	)	$	(18.40	)	$	2.88		$	2.88		$	9.95		$	9.92

For the years ended December 31, 2011, 2010 and 2009, respectively, we have excluded 2.4 million, 2.2 million and 1.7 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 12—Debt.

Other Comprehensive Income

12 Months Ended

Dec. 31, 2011

Other Comprehensive Income

Other Comprehensive Income

Note 9—Other Comprehensive Income

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

	Years ended December 31,
	2011									2010									2009
	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	$	(204	)	$	—		$	(204	)	$	(8	)	$	—		$	(8	)	$	37		$	—	$	37
Unrecognized gain (loss) on derivative instruments	3			(16		)	(13		)	(10		)	(19		)	(29		)	(4		)	2		(2		)
Unrecognized loss on marketable securities	(13		)	—			(13		)	—			—			—			—			—		—
Recognized components of net periodic benefit costs	25			—			25			16			—			16			24			—		24
Recognized (gain) loss on derivative instruments	(1		)	12			11			14			(2		)	12			3			3		6
Recognized loss on marketable securities	13			—			13			—			—			—			1			—		1

Other comprehensive income (loss) before income taxes	(177		)	(4		)	(181		)	12			(21		)	(9		)	61			5		66
Income taxes related to other comprehensive income	13			—			13			(9		)	—			(9		)	24			—		24
Other comprehensive income (loss), net of tax	$	(164	)	$	(4	)	$	(168	)	$	3		$	(21	)	$	(18	)	$	85		$	5	$	90

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

The components of accumulated other comprehensive income (loss), net of tax, were as follows (in millions):

	December 31, 2011									December 31, 2010
	Controlling interest			Non- controlling interest			Redeemable non- controlling interest			Controlling interest			Non- controlling interest			Redeemable non- controlling interest
Unrecognized components of net periodic benefit costs (a)	$	(501	)	$	—		$	—		$	(335	)	$	—		$	—
Unrecognized gain (loss) on derivative instruments	7			(3		)	(17		)	5			(3		)	(13		)
Unrecognized loss on marketable securities	(2		)	—			—			(2		)	—			—
Accumulated other comprehensive income (loss)	$	(496	)	$	(3	)	$	(17	)	$	(332	)	$	(3	)	$	(13	)

(a) Amounts are net of income tax effect of $49 million and $36 million for December 31, 2011 and 2010, respectively.

- Definition

This label may include the following: 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. Components of comprehensive income include: (1) foreign currency translation adjustments; (2) gains and losses on foreign currency transactions that are designated as, and are effective as, economic hedges of a net investment in a foreign entity; (3) gains and 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; (4) change in the market value of a futures contract that qualifies as a hedge of an asset reported at fair value; (5) unrealized holding gains and 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; (6) a net loss recognized as an additional pension liability not yet recognized as net periodic pension cost; and (7) the net gain or loss and net prior service cost or credit for pension plans and other postretirement benefit plans.

+ References+ Details

Drilling Fleet

12 Months Ended

Dec. 31, 2011

Drilling Fleet

Drilling Fleet

Note 10—Drilling Fleet

Expansion—Construction work in progress, recorded in property and equipment, was $1.4 billion and $1.5 billion at December 31, 2011 and 2010, respectively. Capital expenditures and other capital additions, including capitalized interest, for our major construction projects for the six years ended December 31, 2011 were as follows (in millions):

	Years ended December 31,
	2011		2010		2009		2008 - 2006		Total
Ultra-Deepwater Floater TBN1 (a)	$	138	$	—	$	—	$	—	$	138
Ultra-Deepwater Floater TBN2 (a)	137		—		—		—		137
Transocean Honor (b)	119		97		—		—		216
Transocean Siam Driller (c)	110		9		—		—		119
Transocean Andaman (c)	110		9		—		—		119
Transocean Ao Thai (d)	79		—		—		—		79
Deepwater Champion (e) (f)	43		206		263		264		776
Discoverer Luanda (f) (g)	12		174		220		315		721
Discoverer India (f)	6		203		291		250		750
Dhirubhai Deepwater KG2 (f) (h)	—		36		371		270		677
Development Driller III (e) (f)	—		24		117		483		624
Discoverer Inspiration (f)	—		12		224		443		679
Discoverer Americas (f)	—		6		148		478		632
Discoverer Clear Leader (f)	—		6		115		516		637
Petrobras 10000 (f) (i)	—		6		735		—		741
Dhirubhai Deepwater KG1 (f) (h)	—		—		295		384		679
Sedco 700-series upgrades (f)	—		—		71		520		591
Capitalized interest	39		89		182		240		550
Mobilization costs	20		89		155		—		264
Total	$	813	$	966	$	3,187	$	4,163	$	9,129

(a) The costs for Ultra-Deepwater Floater TBN1 and Ultra-Deepwater Floater TBN2 include our initial investments of $136 million and $136 million, respectively, representing the estimated fair values of the rigs at the time of our acquisition of Aker Drilling in October 2011. The fair values of our initial investments are preliminary and subject to change. See Note 4—Business Combination.

(b) In November 2010, we purchased Transocean Honor, a PPL Pacific Class 400 design jackup, which is under construction at PPL Shipyard Pte Ltd. in Singapore and is expected for delivery in the first quarter of 2012.

(c) In December 2010, we purchased Transocean Siam Driller and Transocean Andaman, two Keppel FELS Super B class design jackups, which are under construction at Keppel FELS’ yard in Singapore and are expected for delivery in the first quarter of 2013.

(d) In June 2011, we purchased Transocean Ao Thai, a Keppel FELS Super B class design jackup, which is under construction at Keppel FELS’ yard in Singapore and is expected for delivery in the third quarter of 2013.

(e) The costs for Deepwater Champion and Development Driller III include our initial investments of $109 million and $350 million, respectively, representing the estimated fair values of the rigs at the time of our merger with GlobalSantaFe Corporation (“GlobalSantaFe”) in November 2007.

(f) The accumulated construction costs of these rigs are no longer included in construction work in progress, as their construction projects had been completed as of December 31, 2011.

(g) The costs for Discoverer Luanda represent 100 percent of expenditures incurred since inception. ADDCL is responsible for all of these costs. We hold a 65 percent interest in the ADDCL joint venture, and Angco Cayman Limited, a Cayman Islands company (“Angco Cayman”), holds the remaining 35 percent interest.

(h) The costs for Dhirubhai Deepwater KG1 and Dhirubhai Deepwater KG2 represent 100 percent of TPDI’s expenditures, including those incurred prior to our investment in the joint venture. TPDI is responsible for all of these costs. We hold a 50 percent interest in the TPDI joint venture, and Quantum Pacific Management Limited, a Cypriot company and successor in interest to Pacific Drilling Limited (“Quantum”), holds the remaining 50 percent interest.

(i) In June 2008, we reached an agreement with a joint venture formed by subsidiaries of Petrobras and Mitsui to acquire Petrobras 10000 under a capital lease contract. In connection with the agreement, we agreed to provide assistance and advisory services for the construction of the rig and operating management services once the rig commenced operations. On August 4, 2009, we accepted delivery of Petrobras 10000 and recorded non-cash additions of $716 million to property and equipment, net, along with a corresponding increase to long-term debt. Total capital additions include $716 million in capital costs incurred by Petrobras and Mitsui for the construction of the drillship and $19 million of other capital expenditures. The capital lease agreement has a 20-year term, after which we will have the right and obligation to acquire the drillship for one dollar. See Note 12—Debt and Note 15—Commitments and Contingencies.

During the year ended December 31, 2011, in connection with our acquisition of Aker Drilling, we acquired two Harsh Environment, Ultra-Deepwater semisubmersibles, Transocean Spitsbergen and Transocean Barents, which are currently operating on long-term contracts in Norway. See Note 4—Business Combination.

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 12—Debt.

Dispositions—During the year ended December 31, 2011, in connection with our efforts to dispose of non-strategic assets, we sold the Standard Jackups, Transocean Mercury, GSF Britannia, George H. Galloway, GSF Labrador, and GSF Adriatic XI, and the swamp barge Searex IV, along with related equipment, and we received net aggregate proceeds of $163 million and recognized a net gain on the disposals of these assets of $19 million ($0.06 per diluted share from continuing operations), which had no tax effect. For the year ended December 31, 2011, we recognized a net loss on disposal of other unrelated assets of $15 million.

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 21—Fair Value of Financial Instruments). 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 ($0.04 per diluted share from continuing operations), which had no tax effect for the year ended December 31, 2010. For the year ended December 31, 2010, we recognized a net gain on disposal of other unrelated assets of $5 million.

During the year ended December 31, 2009, in connection with our sale of Sedco 135-D and disposals of unrelated property and equipment, we received aggregate net proceeds of $18 million, and we recognized a loss on disposal of assets of $9 million ($0.03 per diluted share from continuing operations), which had no tax effect.

Unconsolidated affiliates—During the year ended December 31, 2011, we completed the sale of our 50 percent ownership interest in Overseas Drilling Limited, a Cayman Islands company, which owns the drillship Joides Resolution, which was adapted for scientific research. In connection with the sale, we received net proceeds of $22 million and recognized a net gain of $13 million ($0.04 per diluted share from continuing operations), recorded in other, net, which had no tax effect.

During the year ended December 31, 2009, we received net proceeds of $4 million in exchange for our 45 percent ownership interest in Caspian Drilling Company Limited, which operates Dada Gorgud and Istigal under long-term bareboat charters with the owner of the rigs and $38 million in exchange for our 40 percent ownership interest in Arab Drilling & Workover Company. In connection with the sales of our ownership interests, we recognized an aggregate net gain of $30 million ($0.09 per diluted share from continuing operations), recorded in other, net on our consolidated statement of operations.

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. During 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, for the year ended December 31, 2010, 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 15—Commitments and Contingencies.

Goodwill and Other Intangible Assets

12 Months Ended

Dec. 31, 2011

Goodwill and Other Intangible Assets

Goodwill and Other Intangible Assets

Note 11—Goodwill and Other Intangible Assets

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

	Year ended December 31, 2011								Year ended December 31, 2010
	Gross carrying amount		Accumulated impairment			Net carrying amount			Gross carrying amount		Accumulated impairment			Net carrying amount
Contract drilling services
Balance, beginning of period	$	10,626	$	(2,494	)	$	8,132		$	10,626	$	(2,494	)	$	8,132
Impairment	—		(5,200		)	(5,200		)	—		—			—
Business combination	273		—			273			—		—			—
Balance, end of period	10,899		(7,694		)	3,205			10,626		(2,494		)	8,132

Drilling management services
Balance, beginning of period	176		(176		)	—			176		(176		)	—
Balance, end of period	176		(176		)	—			176		(176		)	—

Total goodwill
Balance, beginning of period	10,802		(2,670		)	8,132			10,802		(2,670		)	8,132
Impairment	—		(5,200		)	(5,200		)	—		—			—
Business combination	273		—			273			—		—			—
Balance, end of period	$	11,075	$	(7,870	)	$	3,205		$	10,802	$	(2,670	)	$	8,132

The gross carrying amounts of the ADTI trade name, which we consider to be an indefinite-lived intangible asset, and accumulated impairment were as follows (in millions):

	Year ended December 31, 2011							Year ended December 31, 2010
	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
Balance, end of period	$	76	$	(37	)	$	39	$	76	$	(37	)	$	39

Definite-lived intangible assets—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, 2011								Year ended December 31, 2010
	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	$	(185	)	$	6		$	191	$	(167	)	$	24
Amortization	—		(6		)	(6		)	—		(18		)	(18		)
Balance, end of period	191		(191		)	—			191		(185		)	6

Customer relationships
Balance, beginning of period	148		(89		)	59			148		(84		)	64
Amortization	—		(5		)	(5		)	—		(5		)	(5		)
Balance, end of period	148		(94		)	54			148		(89		)	59

Total definite-lived intangible assets
Balance, beginning of period	339		(274		)	65			339		(251		)	88
Amortization	—		(11		)	(11		)	—		(23		)	(23		)
Balance, end of period	$	339	(285		)	54			$	339	$	(274	)	$	65

Drilling contract intangible liabilities
Balance, beginning of period	$	1,494	$	(1,342	)	$	152		$	1,494	$	(1,226	)	$	268
Amortization	—		(51		)	(51		)	—		(116		)	(116		)
Balance, end of period	$	1,494	(1,393		)	101			$	1,494	$	(1,342	)	$	152

We amortize the drilling contract intangibles over the term of the respective drilling contracts using the straight-line method of amortization, recognized in contract intangible revenues on our consolidated statements of operations. We amortize the customer relationships intangible asset over its 15-year life using the straight-line method of amortization, recognized in operating and maintenance expense on our consolidated statements of operations. The estimated net future amortization related to intangible assets and liabilities as of December 31, 2011, was as follows (in millions):

Years ending December 31,	Drilling contract intangibles			Customer relationships
2012	$	(41	)	$	5
2013	(25		)	5
2014	(15		)	5
2015	(14		)	5
2016	(6		)	5
Thereafter	—			29
Total intangible assets (liabilities), net	$	(101	)	$	54

- Definition

Discloses the aggregate amount of goodwill and a description of intangible assets and liabilities, which may include (a) for amortizable intangible assets (also referred to as finite-lived intangible assets) and liabilities, 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 and liabilities in total and by major class, the gross carrying amount and accumulated amortization, the total amortization for the period, and the estimated aggregate amortization 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 or 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. This element may be used as a single block of text to include the entire intangible asset disclosure including data and tables.

+ References+ Details

Debt

12 Months Ended

Dec. 31, 2011

Debt

Debt

Note 12—Debt

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

	December 31, 2011						December 31, 2010
	Transocean Ltd. and subsidiaries		Consolidated variable interest entities		Consolidated total		Transocean Ltd. and subsidiaries		Consolidated variable interest entities		Consolidated total
ODL Loan Facility	$	—	$	—	$	—	$	10	$	—	$	10
Commercial paper program (a)	—		—		—		88		—		88
6.625% Notes due April 2011 (a)	—		—		—		167		—		167
5% Notes due February 2013	253		—		253		255		—		255
5.25% Senior Notes due March 2013 (a)	507		—		507		511		—		511
TPDI Credit Facilities due March 2015	—		473		473		—		560		560
4.95% Senior Notes due November 2015 (a)	1,120		—		1,120		1,099		—		1,099
Aker Revolving Credit and Term Loan Facility due December 2015	594		—		594		—		—		—
5.05% Senior Notes due December 2016 (a)	999		—		999		—		—		—
Callable Bonds due February 2016	267		—		267		—		—		—
ADDCL Credit Facilities due December 2017	—		217		217		—		242		242
Eksportfinans Loans due January 2018	884		—		884		—		—		—
6.00% Senior Notes due March 2018 (a)	998		—		998		997		—		997
7.375% Senior Notes due April 2018 (a)	247		—		247		247		—		247
TPDI Notes due October 2019	—		148		148		—		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		—		—		—
7.45% Notes due April 2027 (a)	97		—		97		96		—		96
8% Debentures due April 2027 (a)	57		—		57		57		—		57
7% Notes due June 2028	311		—		311		313		—		313
Capital lease contract due August 2029	676		—		676		694		—		694
7.5% Notes due April 2031 (a)	598		—		598		598		—		598
1.625% Series A Convertible Senior Notes due December 2037 (a)	—		—		—		11		—		11
1.50% Series B Convertible Senior Notes due December 2037 (a)	30		—		30		1,625		—		1,625
1.50% Series C Convertible Senior Notes due December 2037 (a)	1,663		—		1,663		1,605		—		1,605
6.80% Senior Notes due March 2038 (a)	999		—		999		999		—		999
7.35% Senior Notes due December 2041 (a)	300		—		300		—		—		—
Total debt	12,698		838		13,536		10,271		950		11,221
Less debt due within one year
ODL Loan Facility	—		—		—		10		—		10
Commercial paper program (a)	—		—		—		88		—		88
6.625% Notes due April 2011 (a)	—		—		—		167		—		167
TPDI Credit Facilities due March 2015	—		70		70		—		70		70
Aker Revolving Credit and Term Loan Facility due December 2015	90		—		90		—		—		—
ADDCL Credit Facilities due November 2017	—		27		27		—		25		25
Eksportfinans Loans due January 2018	142		—		142		—		—		—
Capital lease contract due August 2029	17		—		17		16		—		16
1.625% Series A Convertible Senior Notes due December 2037 (a)	—		—		—		11		—		11
1.50% Series B Convertible Senior Notes due December 2037 (a)	30		—		30		1,625		—		1,625
1.50% Series C Convertible Senior Notes due December 2037 (a)	1,663		—		1,663		—		—		—
Total debt due within one year	1,942		97		2,039		1,917		95		2,012
Total long-term debt	$	10,756	$	741	$	11,497	$	8,354	$	855	$	9,209

(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 commercial paper program and the Five-Year 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 Statements.

Scheduled maturities—In preparing the scheduled maturities of our debt, we assume the noteholders will exercise their options to require us to repurchase the 1.50% Series C Convertible Senior Notes in December 2012. At December 31, 2011, 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,
2012	$	2,001		$	97	$	2,098
2013	1,002			98		1,100
2014	235			99		334
2015	1,331			322		1,653
2016	1,696			34		1,730
Thereafter	6,450			188		6,638
Total debt, excluding unamortized discounts, premiums and fair value adjustments	12,715			838		13,553
Total unamortized discounts, premiums and fair value adjustments	(17		)	—		(17		)
Total debt	$	12,698		$	838	$	13,536

Commercial paper program—We maintain a commercial paper program (the “Program”), which is supported by the Five-Year Revolving Credit Facility, under which we may issue privately placed, unsecured commercial paper notes for general corporate purposes up to a maximum aggregate outstanding amount of $1.5 billion. Proceeds from commercial paper issuance under the Program may be used for general corporate purposes. At December 31, 2011, we had no commercial paper outstanding.

Five-Year Revolving Credit Facility—We have a $2.0 billion revolving credit facility under the Five-Year Revolving Credit Facility Agreement dated November 1, 2011 (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 our Debt Rating (based on our current Debt Rating, a margin of 1.625 percent) or (2) the Base Rate plus the Five-Year Revolving Credit Facility Margin, less one percent per annum. Throughout the term of the Five-Year Revolving Credit Facility, we pay a facility fee on the daily amount of the underlying commitment, whether used or unused, which ranges from 0.13 percent to 0.33 percent, based on our Debt Rating, and was 0.275 percent at December 31, 2011. The Five-Year Revolving Credit Facility expires on November 1, 2016, and borrowings may be prepaid in whole or in part without premium or penalty. 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. At December 31, 2011, we had $24 million in letters of credit issued and outstanding, we had no borrowings outstanding, and we had $2.0 billion available borrowing capacity under the Five-Year Revolving Credit Facility.

6.625% Notes—In April 2001, we issued $700 million aggregate principal amount of 6.625% Notes due April 2011. On April 15, 2011, we repaid the 6.625% Notes at maturity.

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 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. The indentures related to the 5% Notes and the 7% Notes contain limitations on creating liens and sale/leaseback transactions. At December 31, 2011, $250 million and $300 million aggregate principal amount of the 5% Notes and the 7% Notes, respectively, remained outstanding. See Note 13—Derivatives and Hedging.

5.25%, 6.00% and 6.80% Senior Notes—In December 2007, Transocean Inc. 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”). Transocean Inc. 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. 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, 2011, $500 million, $1.0 billion and $1.0 billion principal amount of the 5.25% Senior Notes, the 6.00% Senior Notes and the 6.80% Senior Notes, respectively, were outstanding. See Note 13—Derivatives and Hedging.

TPDI Credit Facilities—TPDI has a bank credit agreement for a $1.265 billion secured credit facility (the “TPDI Credit Facilities”), comprised of a $1.0 billion senior term loan, a $190 million junior term loan and a $75 million revolving credit facility, which was established to finance the construction of and is secured by Dhirubhai Deepwater KG1 and Dhirubhai Deepwater KG2. 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 may be prepaid in whole or in part without premium or penalty. 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. At December 31, 2011, $945 million was outstanding under the TPDI Credit Facilities, of which $472 million was due to one of our subsidiaries and was eliminated in consolidation. The weighted-average interest rate on December 31, 2011 was 2.2 percent. See Note 13—Derivatives and Hedging.

In April 2010, TPDI obtained a letter of credit in the amount of $60 million to satisfy its liquidity requirements under the TPDI Credit Facilities. The letter of credit was issued under an uncommitted credit facility that has been established by one of our subsidiaries. Additionally, TPDI is required to maintain certain cash balances in restricted accounts for the payment of the scheduled installments on the TPDI Credit Facilities. TPDI had restricted cash investments of $23 million at December 31, 2011 and 2010.

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, 2011, $1.1 billion and $900 million aggregate principal amount of the 4.95% Senior Notes and the 6.50% Senior Notes, respectively, were outstanding. See Note 13—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 the credit rating for the notes assigned by Moody’s Investors Service or Standard & Poor’s Ratings Services. We are required to pay interest on the 2011 Senior Notes on June 15 and December 15 of each year, beginning June 15, 2012. 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. 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. At December 31, 2011, $1.0 billion, $1.2 billion and $300 million aggregate principal amount of the 5.05% Senior Notes, the 6.375% Senior Notes and the 7.35% Senior Notes, respectively, were outstanding.

Aker Revolving Credit and Term Loan Facility—In connection with our acquisition of Aker Drilling, we assumed the outstanding borrowings under a credit facility established by the Revolving Credit and Term Loan Facility Agreement dated February 21, 2011 (the “Aker Revolving Credit and Term Loan Facility”), comprised of a $500 million revolving credit facility and a $400 million term loan, which is secured by Transocean Spitsbergen and Transocean Barents. The Aker Revolving Credit and Term Loan Facility bears interest at LIBOR plus a margin of 2.50 percent and mandatory costs, and requires scheduled quarterly installments on the term loan. The Aker Revolving Credit and Term Loan Facility expires in December 2015 and may be prepaid in whole or in part without premium or penalty. The Aker Revolving Credit and Term Loan Facility includes covenants requiring minimum liquidity, a maximum leverage ratio, a minimum interest coverage ratio, a minimum current ratio, and a minimum equity ratio, as defined. At December 31, 2011, $594 million was outstanding under the Aker Revolving Credit and Term Loan Facility at a weighted-average interest rate of 3.0 percent.

Callable Bonds—In connection with our acquisition of Aker Drilling, we assumed the obligations associated with the FRN Aker Drilling ASA Senior Unsecured Callable Bond Issue 2011/2016 (the “FRN Callable Bonds”) and 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”), on February 21, 2011, which are publicly traded on the Oslo Stock Exchange. The FRN Callable Bonds and the 11% Callable Bonds are denominated in Norwegian kroner in the aggregate principal amounts of NOK 940 million and NOK 560 million, respectively. 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, 2011, 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 $158 million and $94 million, respectively, using an exchange rate of NOK 5.9631 to US $1.00. See Note 13—Derivatives and Hedging.

ADDCL Credit Facilities—ADDCL has a senior secured bank credit agreement for a credit facility (the “ADDCL Primary Loan Facility”) comprised of Tranche A and Tranche C for $215 million and $399 million, respectively, which was established to finance the construction of and is secured by Discoverer Luanda. 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 payments and matures in December 2017. 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, 2011, $190 million was outstanding under Tranche A at a weighted-average interest rate of 1.5 percent. At December 31, 2011, $399 million was outstanding under Tranche C, which was eliminated in consolidation.

Additionally, ADDCL has a secondary bank credit agreement for a $90 million credit facility (the “ADDCL Secondary Loan Facility” and together with the ADDCL Primary Loan Facility, the “ADDCL Credit Facilities”), for which one of our subsidiaries provides 65 percent of the total commitment. The facility bears interest at LIBOR plus the applicable margin, ranging from 3.125 percent to 5.125 percent, depending on certain milestones. 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. 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 the occurrence of a credit rating assignment of less than Baa3 or BBB- by Moody’s Investors Service or Standard & Poor’s Ratings Services, respectively, for Transocean Inc.’s long-term, unsecured, unguaranteed and unsubordinated indebtedness. At December 31, 2011, $78 million was outstanding under the ADDCL Secondary Loan Facility, of which $51 million was provided by one of our subsidiaries and has been eliminated in consolidation. The weighted-average interest rate on December 31, 2011 was 3.7 percent.

ADDCL is required to maintain certain cash balances in restricted accounts for the payment of the scheduled installments on the ADDCL Credit Facilities. ADDCL had restricted cash investments of $16 million at December 31, 2011 and 2010.

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”), which were established to finance the construction and delivery of Transocean Spitsbergen and Transocean Barents. 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, 2011, $427 million and $462 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, 2011, the aggregate principal amount of the Aker Restricted Cash Investments was $889 million.

7.375% Senior Notes—In March 2002, we issued $247 million principal amount of our 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, 2011, $246 million principal amount of the 7.375% Senior Notes was outstanding.

TPDI Notes—TPDI has issued promissory notes (the “TPDI Notes”) payable to its two shareholders, Quantum and one of our subsidiaries, which have maturities through October 2019. At December 31, 2011, the aggregate outstanding principal amount was $296 million, of which $148 million was due to one of our subsidiaries and has been eliminated in consolidation. The weighted-average interest rate on December 31, 2011 was 2.5 percent.

7.5% Notes—In April 2001, Transocean Inc. issued $600 million aggregate principal amount of 7.5% Notes due April 2031. 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, 2011, $600 million principal amount of 7.5% Notes was outstanding.

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 7.45% Notes and the 8% Debentures are redeemable at any time at Transocean Inc.’s option subject to a make-whole premium. 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. At December 31, 2011, $100 million and $57 million principal amount of the 7.45% Notes and the 8% Debentures, respectively, were outstanding.

Capital lease contract—In August 2009, we accepted delivery of Petrobras 10000, an asset held under capital lease, and we recorded non-cash capital additions of $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 10—Drilling Fleet and Note 15—Commitments and Contingencies.

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, 2011, the Convertible Senior Notes could be converted under the circumstances specified below at a rate of 6.1902 shares per $1,000 note, equivalent to a conversion price of $161.55 per share, subject to adjustments upon the occurrence of certain events. In the event of certain fundamental changes that occur on or before December 20, 2012 with respect to Series C Convertible Senior Notes, we will, in some cases, increase the conversion rate for a holder electing to convert notes in connection with such fundamental change. Upon conversion, we will 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 may 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, 2011, 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 may 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 have the right to require us to repurchase their notes on December 14, 2012, 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 Convertible Senior Notes were as follows (in millions):

	December 31, 2011							December 31, 2010
	Principal amount		Unamortized discount			Carrying amount		Principal amount		Unamortized discount			Carrying amount
Carrying amount of liability component
Series A Convertible Senior Notes due 2037	$	—	$	—		$	—	$	11	$	—		$	11
Series B Convertible Senior Notes due 2037	30		—			30		1,680		(55		)	1,625
Series C Convertible Senior Notes due 2037	1,722		(59		)	1,663		1,722		(117		)	1,605

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

	December 31,
	2011		2010
Carrying amount of equity component
Series A Convertible Senior Notes due 2037	$	—	$	1
Series B Convertible Senior Notes due 2037	4		210
Series C Convertible Senior Notes due 2037	276		276

Including the amortization of the unamortized discount, the effective interest rates for the Series C Convertible Senior Notes was 5.28 percent. At December 31, 2011, 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,
	2011		2010		2009
Interest expense
Series A Convertible Senior Notes due 2037	$	—	$	58	$	85
Series B Convertible Senior Notes due 2037	78		98		100
Series C Convertible Senior Notes due 2037	84		98		100

Holders of the Series B Convertible Senior Notes had the option to require us to repurchase all or any part of such holders’ notes on December 15, 2011. As a result, we were required to repurchase an aggregate principal amount of $1.7 billion of our Series B Convertible Senior Notes for an aggregate cash payment of $1.7 billion. See Note 28—Subsequent Events.

Holders of the Series A Convertible Senior Notes had the option to require us to repurchase all or any part of such holders’ notes on December 15, 2010. As a result, we were required to repurchase an aggregate principal amount of $1,288 million of our Series A Convertible Senior Notes for an aggregate cash payment of $1,288 million. In January 2011, we redeemed the remaining $11 million aggregate principal amount of the Series A Convertible Senior Notes.

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.

During the year ended December 31, 2009, we repurchased an aggregate principal amount of $901 million of the Series A Convertible Senior Notes for an aggregate cash payment of $865 million. We recognized a loss of $28 million associated with the debt component of the instrument and recorded additional paid-in capital of $22 million associated with the equity component.

Derivatives and Hedging

12 Months Ended

Dec. 31, 2011

Derivatives and Hedging

Derivatives and Hedging

Note 13—Derivatives and Hedging

Derivatives designated as hedging instruments—Two of our wholly owned subsidiaries have entered into 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 4.95% Senior Notes, 5.25% Senior Notes and the 5% Notes. 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 perfectly offset changes in the fair value of the hedged fixed-rate notes. Through the stated maturities of the interest rate swaps, 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 London Interbank Offered Rate plus a margin.

Additionally, TPDI has entered into interest rate swaps, which have been designated and have qualified as a cash flow hedge, to reduce the variability of cash interest payments associated with the variable rate borrowings under the TPDI Credit Facilities. The aggregate notional amount corresponds with the aggregate outstanding amount of the borrowings under the TPDI Credit Facilities.

Aker Drilling entered into cross-currency interest rate swaps, which we have designated and which qualify as a cash flow hedge, to reduce the variability of cash interest payments associated with the changes in the U.S. dollar to Norwegian kroner exchange rate. The aggregate notional amount corresponds with the aggregate outstanding amount of the Callable Bonds.

At December 31, 2011, 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):

	Aggregate notional amount		Weighted average variable rate		Weighted average fixed rate
Interest rate swaps, fair value hedges	$	1,400	3.7	%	5.1	%
Interest rate swaps, cash flow hedges	455		0.6	%	2.3	%

At December 31, 2011, the aggregate notional amounts associated with our cross-currency derivatives designated as hedging instruments were as follows (in millions, except weighted average interest rates):

	Pay				Receive
	USD- denominated notional amount		Weighted average fixed rate		NOK- denominated notional amount		Weighted average fixed rate
Cross-currency swaps, cash flow hedges	$	102	8.9	%	NOK	560	11	%

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	2011		2010
Interest rate swaps, fair value hedges	Other current assets	$	5	$	4
Interest rate swaps, fair value hedges	Other assets	31		17
Interest rate swaps, cash flow hedges	Other long-term liabilities	16		13
Cross-currency swaps, cash flow hedges	Other long-term liabilities	7		—

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

		Year ended December 31,
	Statement of operations classification	2011		2010
Loss associated with effective portion	Interest expense, net of amounts capitalized	$	11	$	12

Derivatives not designated as hedging instruments—In connection with our acquisition of Aker Drilling, we assumed certain interest rate swaps that are not designated as hedging instruments. At December 31, 2011, the aggregate notional amounts and the weighted average interest rates associated with our derivatives not designated as hedging instruments were as follows (in millions, except weighted average interest rates):

	Aggregate notional amount		Weighted average variable rate		Weighted average fixed rate
Interest rate swaps not designated as hedging instruments	$	305	0.5	%	4.2	%

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	2011		2010
Interest rate swaps not designated as hedging instruments	Other long-term liabilities	$	15	$	—

On August 17, 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 kroner exchange rate. The aggregate notional amount and the exchange rate associated with the forward exchange contract were as follows (in millions, except exchange rate):

	Aggregate notional amount				Exchange
	Pay		Receive		rate
Forward exchange contract	$	1,120	NOK	6,051	5.4005

During the year ended December 31, 2011, we settled the full amount of the forward exchange contract, and, as a result, we recognized a loss on foreign exchange in the amount of $78 million, recorded in other, net.

Additionally, in connection with our acquisition of Aker Drilling, we assumed other derivative instruments, which were not designated as hedging instruments for accounting purposes. On the acquisition date, we recognized a liability for these undesignated derivative instruments, measured at fair value, in the aggregate amount of $12 million. In October 2011, we terminated these other undesignated derivative instruments for an aggregate cash payment of $15 million and recognized a loss on the terminations in the amount of $3 million, recorded in other, net.

Postemployment Benefit Plans

12 Months Ended

Dec. 31, 2011

Postemployment Benefit Plans

Postemployment Benefit Plans

Note 14—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 several funded defined benefit plans, primarily group pension schemes with life insurance companies, and two unfunded plans, covering our eligible Norway employees and former employees (the “Norway Plans”). In connection with our acquisition of Aker Drilling, we assumed the obligations under three funded defined benefit plans, under group pension schemes with life insurance companies, covering eligible Norway employees (the “Assumed 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, the Assumed 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, 2011						December 31, 2010
	U.S. Plans		Non-U.S. Plans		OPEB Plans		U.S. Plans		Non-U.S. Plans		OPEB Plans
Discount rate	4.66	%	4.90	%	4.28	%	5.48	%	5.81	%	4.92	%
Compensation trend rate	4.22	%	4.30	%	n/a		4.24	%	4.65	%	n/a

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

	Year ended December 31, 2011						Year ended December 31, 2010						Year ended December 31, 2009
	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	5.49	%	5.73	%	4.94	%	5.86	%	5.67	%	5.51	%	5.41	%	6.06	%	5.34	%
Expected rate of return	8.49	%	6.42	%	n/a		8.49	%	6.65	%	n/a		8.50	%	6.59	%	n/a
Compensation trend rate	4.24	%	4.62	%	n/a		4.21	%	4.77	%	n/a		4.21	%	4.55	%	n/a
Health care cost trend rate
-initial	n/a		n/a		8.08	%	n/a		n/a		8.00	%	n/a		n/a		8.99	%
-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		2018		n/a		n/a		2016		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, 2011												Year ended December 31, 2010
	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	$	1,068		$	374		$	56		$	1,498		$	932		$	403		$	54		$	1,389
Assumed projected benefit obligation	—			17			—			17			—			—			—			—
Actuarial (gains) losses, net	128			24			(3		)	149			89			(46		)	2			45
Service cost	43			21			1			65			42			20			1			63
Interest cost	58			22			3			83			54			20			3			77
Foreign currency exchange rate	—			(1		)	—			(1		)	—			(13		)	—			(13		)
Benefits paid	(37		)	(12		)	(5		)	(54		)	(51		)	(14		)	(5		)	(70		)
Participant contributions	—			2			1			3			—			2			1			3
Special termination benefits	—			—			—			—			3			—			—			3
Settlements and curtailments	—			—			—			—			(1		)	2			—			1
Projected benefit obligation, end of period	1,260			447			53			1,760			1,068			374			56			1,498

Change in plan assets
Fair value of plan assets, beginning of period	697			332			—			1,029			594			281			—			875
Fair value of acquired plan assets	—			9			—			9			—			—			—			—
Actual return on plan assets	39			(8		)	—			31			85			29			—			114
Foreign currency exchange rate changes	—			2			—			2			—			(11		)	—			(11		)
Employer contributions	70			29			4			103			69			45			4			118
Participant contributions	—			2			1			3			—			2			1			3
Benefits paid	(37		)	(12		)	(5		)	(54		)	(51		)	(14		)	(5		)	(70		)
Settlement and curtailments	—			(3		)	—			(3		)	—			—			—			—
Fair value of plan assets, end of period	769			351			—			1,120			697			332			—			1,029

Funded status, end of period	$	(491	)	$	(96	)	$	(53	)	$	(640	)	$	(371	)	$	(42	)	$	(56	)	$	(469	)

Balance sheet classification, end of period:
Pension asset, non-current	$	—		$	—		$	—		$	—		$	—		$	(8	)	$	—		$	(8	)
Accrued pension liability, current	3			5			3			11			3			2			4			9
Accrued pension liability, non-current	488			91			50			629			368			48			52			468
Accumulated other comprehensive income (loss) (a)	(437		)	(111		)	(2		)	(550		)	(308		)	(61		)	(2		)	(371		)

(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, 2011								December 31, 2010
	U.S. Plans		Non-U.S. Plans		OPEB Plans		Total		U.S. Plans		Non-U.S. Plans		OPEB Plans		Total
Projected benefit obligation	$	1,260	$	447	$	53	$	1,760	$	1,068	$	290	$	56	$	1,414
Fair value of plan assets	769		351		—		1,120		697		248		—		945

The accumulated benefit obligation for all defined benefit pension plans was $1.5 billion and $1.3 billion at December 31, 2011 and 2010, 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, 2011								December 31, 2010
	U.S. Plans		Non-U.S. Plans		OPEB Plans		Total		U.S. Plans		Non-U.S. Plans		OPEB Plans		Total
Accumulated benefit obligation	$	1,083	$	288	$	53	$	1,424	$	921	$	269	$	56	$	1,246
Fair value of plan assets	769		254		—		1,023		697		248		—		945

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 and the Assumed Norway Plans, we establish minimum returns under the terms of investment contracts with insurance companies.

As of December 31, 2011 and 2010, 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				2011				2010
	U.S. Plans		Non-U.S. Plans		U.S. Plans		Non-U.S. Plans		U.S. Plans		Non-U.S. Plans
Equity securities	65	%	51	%	64	%	47	%	65	%	53	%
Fixed income securities	35	%	14	%	36	%	12	%	34	%	10	%
Other investments	—	%	35	%	—	%	41	%	1	%	37	%
Total	100	%	100	%	100	%	100	%	100	%	100	%

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
Equity securities:
U.S.	$	395	$	—	$	395	$	—	$	29	$	29	$	395	$	29	$	424
Non-U.S.	91		—		91		2		137		139		93		137		230
Total equity securities	486		—		486		2		166		168		488		166		654

Fixed income securities:
U.S. government	52		—		52		—		—		—		52		—		52
U.S. corporate	9		—		9		—		—		—		9		—		9
Non-U.S. government	178		—		178		—		43		43		178		43		221
Non-U.S. corporate	39		—		39		—		—		—		39		—		39
Total fixed income securities	278		—		278		—		43		43		278		43		321

Other investments:
Cash	3		38		41		—		—		—		3		38		41
Property	—		—		—		—		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

As of December 31, 2010, the investments for our funded Transocean Plans were categorized as follows (in millions):

	December 31, 2010
	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
Equity securities:
U.S.	$	359	$	—	$	359	$	—	$	28	$	28	$	359	$	28	$	387
Non-U.S.	91		—		91		2		148		150		93		148		241
Total equity securities	450		—		450		2		176		178		452		176		628

Fixed income securities:
U.S. government	59		—		59		—		—		—		59		—		59
U.S. corporate	175		—		175		—		—		—		175		—		175
Non-U.S. government	—		—		—		—		34		34		—		34		34
Non-U.S. corporate	7		—		7		—		—		—		7		—		7
Total fixed income securities	241		—		241		—		34		34		241		34		275

Other investments:
Cash	4		31		35		—		—		—		4		31		35
Property	—		—		—		—		7		7		—		7		7
Investment contracts	—		—		—		—		84		84		—		84		84
Total other investments	4		31		35		—		91		91		4		122		126

Total investments	$	695	$	31	$	726	$	2	$	301	$	303	$	697	$	332	$	1,029

The U.S. Plans invest in passively managed funds that reference market indices. The Non-U.S. Plans invest in actively managed funds that are measured for performance against relevant index benchmarks or that 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, 2011									Year ended December 31, 2010									Year ended December 31, 2009
	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	$	43		$	21		$	64		$	42		$	20		$	62		$	44		$	18		$	62
Interest cost	58			22			80			54			20			74			50			17			67
Expected return on plan assets	(63		)	(23		)	(86		)	(58		)	(17		)	(75		)	(55		)	(16		)	(71		)
Settlements and curtailments	2			1			3			5			3			8			4			2			6
Special termination benefits	—			—			—			3			—			3			—			—			—
Actuarial losses, net	23			4			27			13			4			17			18			2			20
Prior service cost (credit), net	(1		)	—			(1		)	(1		)	—			(1		)	(1		)	1			—
Transition obligation, net	—			—			—			—			1			1			—			—			—
Net periodic benefit costs	$	62		$	25		$	87		$	58		$	31		$	89		$	60		$	24		$	84

For the OPEB Plans, the combined components of net periodic benefit costs, including service cost, interest cost, amortization of prior service cost and recognized net actuarial losses were $1 million, $2 million and $3 million for the years ended December 31, 2011, 2010 and 2009, 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, 2011												December 31, 2010
	U.S. Plans			Non-U.S. Plans			OPEB Plans			Total			U.S. Plans			Non-U.S. Plans		OPEB Plans			Total
Actuarial loss, net	$	447		$	113		$	4		$	564		$	319		$	52	$	7		$	378
Prior service cost (credit), net	(10		)	—			(2		)	(12		)	(11		)	8		(5		)	(8		)
Transition obligation, net	—			(2		)	—			(2		)	—			1		—			1
Total	$	437		$	111		$	2		$	550		$	308		$	61	$	2		$	371

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, 2012 (in millions):

	Year ending December 31, 2012
	U.S. Plans			Non-U.S. Plans		OPEB Plans			Total
Actuarial loss, net	$	39		$	4	$	—		$	43
Prior service cost (credit), net	(1		)	—		(1		)	(2		)
Transition obligation, net	—			—		—			—
Total amount expected to be recognized	$	38		$	4	$	(1	)	$	41

Funding contributions—During the years ended December 31, 2011, 2010 and 2009, we contributed $103 million, $118 million and $73 million, respectively, to the Transocean Plans and the OPEB Plans using our cash flows from operations. For the year ending December 31, 2012, we expect to contribute $145 million to the Transocean Plans, and we expect to fund benefit payments of approximately $3 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,
2012	$	41	$	10	$	3	$	54
2013	44		10		3		57
2014	47		10		3		60
2015	50		9		4		63
2016	54		9		4		67
2017-2021	319		62		20		401

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. We recorded approximately $82 million, $69 million and $67 million of expense related to our defined contribution plans for the years ended December 31, 2011, 2010 and 2009, respectively.

- Definition

Description containing the entire pension and other postretirement benefits disclosure as a single block of text.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 158

-Paragraph 7, 21, 22

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5, 6, 7, 8

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 8

-Subparagraph m

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 106

-Paragraph 518

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 87

-Paragraph 264

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph b

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph a

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph h

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph q

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

-Publisher FASB

-Name FASB Staff Position (FSP)

-Number FAS106-2

-Paragraph 20, 21, 22

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

-Publisher FASB

-Name Emerging Issues Task Force (EITF)

-Number 03-2

-Paragraph 8

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

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 30

-Paragraph 26

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

-Publisher FASB

-Name Implementation Guide (Q and A)

-Number FAS88

-Paragraph 63

+ Details

Commitments and Contingencies

12 Months Ended

Dec. 31, 2011

Commitments and Contingencies.

Commitments and Contingencies

Note 15—Commitments and Contingencies

Lease obligations

We have operating lease commitments expiring at various dates, principally for real estate, office space and office equipment. In August 2009, we accepted delivery of Petrobras 10000, an asset held under a capital lease through August 2029. Additionally, in March 2010, we acquired GSF Explorer, an asset formerly held under a capital lease, in exchange for a cash payment terminating the capital lease obligation in the amount of $15 million. Rental expenses for all leases, including leases with terms of less than one year, was approximately $169 million, $98 million and $99 million for the years ended December 31, 2011, 2010 and 2009, respectively. As of December 31, 2011, future minimum rental payments related to noncancellable operating leases and the capital lease were as follows (in millions):

	Capital lease			Operating leases
Years ending December 31,
2012	$	66		$	39
2013	72			39
2014	72			27
2015	72			22
2016	73			21
Thereafter	918			91
Total future minimum rental payment	$	1,273		$	239
Less amount representing imputed interest	(597		)
Present value of future minimum rental payments under capital leases	676
Less current portion included in debt due within one year	(17		)
Long-term capital lease obligation	$	659

The following were the aggregate carrying amount of our assets held under capital lease as of December 31, 2011 and 2010, respectively (in millions):

	December 31,
	2011			2010
Property and equipment, cost	$	742		$	740
Accumulated depreciation	(44		)	(24		)
Property and equipment, net	$	698		$	716

Depreciation expense associated with our assets held under capital lease was $20 million, $23 million and $14 million for the years ended December 31, 2011, 2010 and 2009, respectively. Depreciation expense for GSF Explorer is included only through the date of our acquisition of the rig in March 2010.

Purchase obligations

At December 31, 2011, our purchase obligations, primarily related to our newbuilds, were as follows (in millions):

	Purchase obligations
Years ending December 31,
2012	$	311
2013	592
2014	408
2015	—
2016	—
Thereafter	—
Total	$	1,311

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.

Trial is currently scheduled to commence on March 5, 2012. There can be no assurance as to the outcome of the trial, that the trial will proceed according to the proposed schedule, that we will not enter into a settlement as to some or all of the matters related to the Macondo well incident, including those to be determined at the trial, or a timing or terms of any such settlement.

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. As of December 31, 2011, we have recognized a liability for such loss contingencies in the amount of $1.2 billion. 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, 2011, we have also recognized an asset of $220 million associated with the portion of our estimated losses that we believe is recoverable from insurance. Although we have available policy limits that could result in additional amounts recoverable from insurance, we are not currently able to estimate the amount of such additional recoverable amounts. Our estimates involve a significant amount of judgment. As a result of new information or future developments, some of which could occur very soon, we may adjust our estimated loss contingencies arising out of the Macondo well incident, and the resulting liabilities could have a material adverse effect on our consolidated statement of financial position, results of operations and cash flows. As of December 31, 2010, the amount of the estimated liability was $135 million, and the estimated recoverable amount was $94 million.

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 owns 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. Halliburton Company (“Halliburton”), which provided cementing and mud-logging services to the operator, filed a claim seeking contribution and indemnity under maritime law, contractual indemnity and alleging negligence and gross negligence. Additionally, certain other third parties filed claims for indemnity and contribution.

On April 20, 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. Additionally, we have preserved our right to arbitration under our contract with BP in each of the relevant filings. With regard to the U.S., we are not seeking recovery of monetary damages, but rather a declaration regarding relative fault and contribution via credit, setoff, or recoupment.

The U.S. District Court, Eastern District of Louisiana (the “MDL Court”) has issued an order outlining the trial plan, which will proceed in three phases. The first phase will focus on issues arising out of the conduct of various parties, relevant to the loss of well control at the Macondo well, the ensuing fire and explosion on Deepwater Horizon on April 20, 2010, the sinking of Deepwater Horizon on April 22, 2010, and the initiation of the release of oil during those time periods. The second phase will address conduct relating 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 that time period. The third, and final, phase will involve consideration of issues relating to containing oil discharged by controlled burning, application of dispersants, use of booms, skimming and other methods, as well as issues pertaining to the migration paths and end locations of oil released.

Notices of alleged non-compliance—The final Joint Investigation Team report was issued on September 14, 2011. Subsequently, 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. While we cannot predict or provide assurance as to the full outcome of these citations, they could result in the assessment of civil penalties. Our appeal is stayed by mutual agreement with the Department of Interior until a ruling is issued in the MDL.

Insurance coverage—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. In response, many of our 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 obligation to the operator. 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. We, Anadarko and MOEX each have entered into the declaratory judgment actions. The actions have been transferred to the MDL for discovery purposes in the U.S. District Court, Eastern District of Louisiana. On November 15, 2011, the court ruled that coverage rights are limited to the scope of Transocean’s indemnity of BP in the drilling contract. Proposed final judgments have been submitted to and are under consideration by the court. The court’s ruling may be appealed.

At the time of the Macondo well incident, our excess liability insurance program offered aggregate insurance coverage of $950 million, exclusive of 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 $250 million fifth layer contains different contractual terms, compared to the first four layers, with regard to additional insured status, such that we believe with reasonable certainty that BP, Anadarko and MOEX do not have contractual right to additional insured status under that layer of our insurance program.

Additionally, our first layer of excess insurers 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. A protocol has been executed by the parties to the suits, and claims have been submitted to the court for review. The parties to the interpleaders have agreed to a protocol to facilitate the reimbursement and funding of settlements of personal injury and fatality claims of our crew and vendors using insurance funds. To date, no payments have yet been received.

Litigation—As of December 31, 2011, 349 actions or claims were pending against us and certain of our subsidiaries, 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, 2011, we and one or more of our subsidiaries have been named, along with other unaffiliated defendants, in 34 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 U.S. District Court, Eastern District of Louisiana. The complaints generally allege negligence and seek awards of unspecified economic damages and punitive damages. BP, MI-SWACO, Weatherford Ltd. and Cameron International Corporation 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, 2011, we and one or more of our subsidiaries were named, along with other unaffiliated defendants, in 114 individual complaints as well as 184 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. See “—Contractual indemnity.”

Federal securities claims—Two federal securities law class actions are currently pending in the U.S. District Court, Southern District of New York, naming us and certain of our officers and directors as defendants. One of these actions generally allege violations of Section 10(b) of the Securities Exchange Act of 1934 (the “Exchange Act”), Rule 10b-5 promulgated under the Exchange Act and Section 20(a) of the Exchange Act in connection with the Macondo well incident. The plaintiffs are generally seeking awards of unspecified economic damages, including damages resulting from the decline in our stock price after the Macondo well incident. The other action was filed by a former GlobalSantaFe shareholder, alleging that the proxy statement related to our shareholder meeting in connection with our merger with GlobalSantaFe violated Section 14(a) of the Exchange Act, Rule 14a-9 promulgated thereunder and Section 20(a) of the Exchange Act. The plaintiff claims that GlobalSantaFe shareholders received inadequate consideration for their shares as a result of the alleged violations and seeks rescission and compensatory damages. The defendants have filed motions to dismiss each of these claims, and the plaintiffs have responded. The motions have been fully briefed and are pending rulings by the courts.

Other federal statutes—Several of the claimants have made assertions under the statutes, including the Clean Water Act, 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 officers and directors as defendants in the District Courts of the State of Texas. The first case generally alleges breach of fiduciary duty, unjust enrichment, abuse of control, gross mismanagement and waste of corporate assets in connection with the Macondo well incident and the other generally alleges breach of fiduciary duty, unjust enrichment and waste of corporate assets in connection with the Macondo well incident. The plaintiffs are generally seeking, on behalf of us, restitution and disgorgement of all profits, benefits and other compensation from the defendants. Under current schedule orders, an amended consolidated complaint must be filed by the plaintiffs by March 5, 2012.

Government claims—On December 15, 2010, the U.S. Department of Justice (“DOJ”) filed a civil lawsuit against us and other unaffiliated defendants. The complaint alleges violations under OPA and the Clean Water Act, 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 asserts 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 Clean Water Act, for all of the discharges from 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. See Note 28—Subsequent Events.

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 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 served us with informal requests for documents in March 2011, and a grand jury issued a subpoena requesting documents from us on April 13, 2011. We have had a number of communications with the task force since that time, and the task force has made informal requests for additional information from us from time to time. The task force is investigating possible violations by us and certain unaffiliated parties of the Clean Water Act, the Migratory Bird Treaty Act, the Refuse Act, the Endangered Species Act, and the Seaman’s Manslaughter Act, among other federal statues, and possible criminal liabilities including fines under those statues 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 environmental offenses, we may be subject to suspension or debarment as a contractor or subcontractor on certain government contracts, including leases.

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 U.S. District Court, Eastern District of Louisiana. 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 and will proceed in accordance with the MDL scheduling order. 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. The State of Louisiana and BP each have appealed portions of this ruling.

The Mexican States’ OPA claims were dismissed for failure to demonstrate that recovery under OPA was authorized by treaty or executive agreement. This ruling may be appealed.

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. Other than the lawsuits filed by the states discussed above, no further requests have been made or actions taken subsequent to the initial communication.

Wreck removal—By letter dated December 6, 2010, the 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.

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, given the potential amounts involved in connection with the Macondo well incident, the operator has sought to avoid its indemnification obligations. In particular, the operator, in response to our request for indemnification, has generally reserved all of its rights and stated that it could not at this time conclude that it is obligated to indemnify us. In doing so, the operator has asserted that the facts are not sufficiently developed to determine who is responsible and 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, BP 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 BP. See Note 28—Subsequent Events.

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 and the well was plugged. The oil released is in the process of 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 20.0 billion Brazilian reals, equivalent to approximately $11.0 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. The complaint has not been served on us.

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 which 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. The federal court in Rio de Janeiro State has forwarded the report to the federal court in Campos for a decision on the proper jurisdiction for the matter.

The drilling services and charter contracts between us and Chevron provides, 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 believe that we have valid defenses to the threatened civil and criminal claims by the federal prosecutor and intend to defend vigorously against any claims that are brought based on the incident. We also intend to pursue indemnity rights under our contracts with Chevron.

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. The amended complaints resulted in one of our subsidiaries being named as a direct defendant in seven cases. We have or may have an indirect interest in an additional 12 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 none of the seven cases in which we are a named defendant have been scheduled for trial or pre-trial discovery. The preliminary information available on these claims is not sufficient to determine if there is an identifiable period for alleged exposure to asbestos, whether any asbestos exposure in fact occurred, the vessels potentially involved in the claims, or the basis on which the plaintiffs would support claims that their injuries were related to exposure to asbestos. However, the initial evidence available would suggest that we would have significant defenses to liability and damages. None of our companies have manufactured or distributed drilling mud or additives for same, and the handling of such additives by one of our employees would be a relatively infrequent occurrence that likely would have involved a non-asbestos product. In 2011, the Special Master issued a ruling that a Jones Act employer defendant, such as us, cannot be sued for punitive damages, and we expect this ruling to apply to each of our seven 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. One 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. 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 as the beneficiary of a qualified settlement fund, funding from settlements with insurers, assigned rights from insurers and “coverage-in-place” settlement agreements with insurers, and funds received from the commutation of certain insurance policies. 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, 2011, the subsidiary was a defendant in approximately 950 lawsuits. Some of these lawsuits include multiple plaintiffs and we estimate that there are approximately 2,114 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 this subsidiary in 1990. Through December 31, 2011, the amounts expended 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 costs of settlement 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 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 approximately $187 million 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 approximately $235 million 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 responded to the assessment on December 22, 2010, and we currently believe that a substantial majority of the assessment is without merit. 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, 2011, 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.

Contamination litigation

On July 11, 2005, one of our subsidiaries was served with a lawsuit filed on behalf of three landowners in Louisiana in the 12th Judicial District Court for the Parish of Avoyelles, State of Louisiana. The lawsuit named 19 other defendants, all of which were alleged to have contaminated the plaintiffs’ property with naturally occurring radioactive material, produced water, drilling fluids, chlorides, hydrocarbons, heavy metals and other contaminants as a result of oil and gas exploration activities. Experts retained by the plaintiffs issued a report suggesting significant contamination in the area operated by the subsidiary and another codefendant, and claimed that over $300 million would be required to properly remediate the contamination. The experts retained by the defendants conducted their own investigation and concluded that the remediation costs would amount to no more than $2.5 million.

The plaintiffs and the codefendant threatened to add GlobalSantaFe as a defendant in the lawsuit under the “single business enterprise” doctrine contained in Louisiana law. The single business enterprise doctrine is similar to corporate veil piercing doctrines. On August 16, 2006, our subsidiary and its immediate parent company, each of which is an entity that no longer conducts operations or holds assets, filed voluntary petitions for relief under Chapter 11 of the U.S. Bankruptcy Code in the U.S. Bankruptcy Court for the District of Delaware. Later that day, the plaintiffs dismissed our subsidiary from the lawsuit. Subsequently, the codefendant filed various motions in the lawsuit and in the Delaware bankruptcies attempting to assert alter ego and single business enterprise claims against GlobalSantaFe and two other subsidiaries in the lawsuit. The efforts to assert alter ego and single business enterprise theory claims against GlobalSantaFe were rejected by the Court in Avoyelles Parish, and the lawsuit against the other defendant went to trial on February 19, 2007. This lawsuit was resolved at trial with a settlement by the codefendant that included a $20 million payment and certain cleanup activities to be conducted by the codefendant. The codefendant further claimed to receive a right to continue to pursue the original plaintiff’s claims.

The codefendant sought to dismiss the bankruptcies. In addition, the codefendant filed proofs of claim against both our subsidiary and its parent with regard to its claims arising out of the settlement of the lawsuit. On February 15, 2008, the bankruptcy court denied the codefendant’s request to dismiss the bankruptcy case but modified the automatic stay to allow the codefendant to proceed on its claims against the debtors, our subsidiary and its parent, and their insurance companies. The codefendant subsequently filed suit against the debtors and certain of its insurers in the Court of Avoyelles Parish to determine their liability for the settlement. The denial of the motion to dismiss the bankruptcies was appealed. On appeal the bankruptcy cases were ordered to be dismissed, and the bankruptcies were dismissed on June 14, 2010.

On March 10, 2010, GlobalSantaFe and the two subsidiaries filed a declaratory judgment action in State District Court in Houston, Texas against the codefendant and the debtors seeking a declaration that GlobalSantaFe and the two subsidiaries had no liability under legal theories advanced by the codefendant. This action is currently stayed.

On March 11, 2010, the codefendant filed a motion for leave to amend the pending litigation in Avoyelles Parish to add GlobalSantaFe, Transocean Worldwide Inc., its successor and our wholly owned subsidiary, and one of the subsidiaries as well as various additional insurers. Leave to amend was granted and the amended petition was filed. An extension to respond for all purposes was agreed until April 28, 2010 for the debtors, GlobalSantaFe, Transocean Worldwide Inc. and the subsidiary. On April 28, 2010, GlobalSantaFe and its two subsidiaries filed various exceptions seeking dismissal of the Avoyelles Parish lawsuit, which have been denied. Subsequent to denial, GlobalSantaFe and its two subsidiaries filed supervisory writs with the Third Circuit Court of Appeals for the State of Louisiana.

On December 15, 2010, as permitted under the existing Case Management Order, GlobalSantaFe and various subsidiaries served third-party demands joining various insurers in the Avoyelles Parish lawsuit seeking insurance coverage for the claims brought against GlobalSantaFe and such subsidiaries. On January 27, 2011, one of the insurers filed pleadings removing the Avoyelles Parish lawsuit to the United States District Court for the Western District of Louisiana, Alexandria Division (the “Western District Action”). On February 3, 2011, GlobalSantaFe and the two subsidiaries filed motions to dismiss the Western District Action, which are now pending. A motion to remand was filed by the codefendant and a hearing on the motion was held on April 5, 2011. A report and recommendations were issued on April 25, 2011 by the magistrate in favor of granting the motion to remand. Objections to this report were filed with the district court. On September 27, 2011 the district court adopted the report and recommendations and remanded the matter to the state court in Avoyelles Parish. Separately, the removing insurer has filed an appeal of the United States Court of Appeals for the Fifth Circuit challenging the remand order and seeking to stay or enjoin the state court from proceeding until a determination of the appeal. The appeal is currently pending in the initial briefing state.

Subsequent to the remand, a scheduling order has been entered in the Avoyelles Parish lawsuit and a jury trial is set for September 17, 2012. In the interim, discovery is ongoing.

We believe that the legal theories advanced by the codefendant should not be applied against GlobalSantaFe or Transocean Worldwide Inc. Our subsidiary, its parent and GlobalSantaFe intend to continue to vigorously defend against any action taken in an attempt to impose liability against them under the theories discussed above or otherwise and believe they have good and valid defenses thereto. We do not believe that these claims will have a material impact on our consolidated statement of financial position, results of operations or cash flows.

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, 2011, the insured value of our drilling rig fleet was approximately $36.4 billion, excluding our rigs under construction.

Under the hull and machinery program, we generally maintain a $125 million per occurrence deductible, limited to a maximum of $250 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 coverage for wreck removal for an amount up to 25 percent of a rig’s insured value, with any excess generally covered to the extent of our excess liability coverage described below. However, we generally retain the risk for all hull and machinery exposures for our Standard Jackups and swamp barge, which are self-insured through our wholly-owned captive insurance company.

We carry $793 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 crew personal injury liability and on collision liability claims and (2) a separate $5 million per occurrence deductible 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, along with $157 million of the excess liability coverage, of which we have re-insured $25 million in the commercial market. In addition, we generally retain the risk for any liability losses in excess of $1.0 billion.

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 and CMI. 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 generally do not have commercial market insurance coverage for loss of revenue, unless it is contractually required, or for physical damage losses, including liability for wreck removal expenses, to our fleet caused by named windstorms in the U.S. Gulf of Mexico and war perils worldwide.

Letters of credit and surety bonds

We had letters of credit outstanding totaling $650 million and $595 million at December 31, 2011 and 2010, 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 letters of credit outstanding at December 31, 2011 and 2010 was a $60 million letter of credit issued for TPDI to satisfy its liquidity requirements under the TPDI Credit Facilities under an uncommitted credit facility that has been established by one of our subsidiaries (see Note 12—Debt).

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. Surety bonds outstanding totaled $12 million and $27 million at December 31, 2011 and 2010, respectively.

Redeemable Noncontrolling Interest

12 Months Ended

Dec. 31, 2011

Redeemable Noncontrolling Interest

Redeemable Noncontrolling Interest

Note 16—Redeemable Noncontrolling Interest

Quantum owns the 50 percent interest in TPDI that is not owned by us and has the unilateral right to exchange its 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, the carrying amount of Quantum’s interest is presented as redeemable noncontrolling interest on our consolidated balance sheets. Changes in redeemable noncontrolling interest were as follows (in millions):

	Years ended December 31,
	2011			2010			2009
Redeemable noncontrolling interest
Balance, beginning of period	$	25		$	—		$	—
Reclassification from noncontrolling interest	—			26			—
Net income attributable to noncontrolling interest (a)	94			13			—
Other comprehensive loss attributable to noncontrolling interest (a)	(3		)	(14		)	—
Balance, end of period	$	116		$	25		$	—

(a) The noncontrolling interest associated with TPDI was not redeemable during the year ended December 31, 2009.

Shareholders' Equity

12 Months Ended

Dec. 31, 2011

Shareholders' Equity

Shareholders' Equity

Note 17—Shareholders’ Equity

Share issuance—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.

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. In May 2011, we recognized a distribution payable, recorded in other current liabilities, with a corresponding entry to additional paid-in capital. 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. At December 31, 2011, the carrying amount of the unpaid distribution payable was $278 million.

Shares held by subsidiary—In December 2008, we issued 16 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, 2011 and 2010, our subsidiary held approximately 12 million shares and 13 million shares, respectively.

Share repurchase program—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 $3.7 billion, using an exchange rate of USD 1.00 to CHF 0.94 as of the close of trading on December 31, 2011. On February 12, 2010, our board of directors authorized our management to implement the share repurchase program.

During the year ended December 31, 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 2,863,267 of our shares under our share repurchase program for an aggregate purchase price of CHF 257 million, equivalent to $240 million. At December 31, 2011 and 2010, we held 2,863,267 treasury shares purchased under our share repurchase program and recorded at cost.

- Definition

Disclosures related to accounts comprising shareholders' equity, including other comprehensive income. Includes: (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.

+ References+ Details

Share-Based Compensation Plans

12 Months Ended

Dec. 31, 2011

Share-Based Compensation Plans

Share-Based Compensation Plans

Note 18—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 stock options, restricted shares, deferred units, SARs 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, 2011, we had 36 million shares authorized and 15 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, options and SARs generally have a 10-year term during which they are exercisable.

As of December 31, 2011, total unrecognized compensation costs related to all unvested share-based awards totaled $91 million, which is expected to be recognized over a weighted-average period of 1.8 years. We recognized additional share-based compensation expense of $3 million, $12 million and $8 million in connection with modifications of share-based awards for the years ended December 31, 2011, 2010 and 2009, respectively.

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,
	2011		2010		2009
Dividend yield	4%		4%		—
Expected price volatility	40%		39%		49%
Risk-free interest rate	1.97%		2.30%		1.80%
Expected life of options	4.9 years		4.7 years		4.8 years
Weighted-average fair value of options granted	$	19.75	$	30.03	$	26.07

Time-Based Awards

Stock options—The following table summarizes vested and unvested time-based vesting stock option (“time-based options”) activity under our incentive plans during the year ended December 31, 2011:

	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, 2011	1,653,683		$	66.37	5.29	$	5
Granted	194,342		78.76
Exercised	(210,997	)	46.37
Forfeited	(47,515	)	84.77
Expired	(10,229	)	42.79
Outstanding at December 31, 2011	1,579,284		$	70.16	2.67	$	—

Vested and exercisable at December 31, 2011	1,182,287		$	68.13	2.67	$	—

The weighted-average grant-date fair value of time-based options granted during the year ended December 31, 2011 was $19.75 per share. The total pretax intrinsic value of time-based options exercised during the year ended December 31, 2011 was $5 million. At December 31, 2011, 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 396,997 unvested time-based options outstanding as of December 31, 2011.

There were time-based options to purchase 253,288 and 597,898 shares granted during the years ended December 31, 2010 and 2009, respectively. The weighted-average grant-date fair value of time-based options granted was $30.03 and $26.07 per share for the years ended December 31, 2010 and 2009, respectively. There were 289,445 and 980,105 time-based options exercised during the years ended December 31, 2010 and 2009, respectively. The total pretax intrinsic value of time-based options exercised was $11 million and $43 million during the years ended December 31, 2010 and 2009, respectively. There were 470,400 and 656,790 unvested time-based options outstanding as of December 31, 2010 and 2009, respectively.

Restricted shares—The following table summarizes unvested share activity for time-based vesting restricted shares (“time-based shares”) granted under our incentive plans during the year ended December 31, 2011:

	Number of shares		Weighted-average grant-date fair value per share
Unvested at January 1, 2011	3,939		$	132.32
Vested	(3,939	)	132.32
Unvested at December 31, 2011	—		$	—

We did not grant time-based shares during the years ended December 31, 2011, 2010 and 2009. There were 92,573 and 320,782 time-based shares that vested during the years ended December 31, 2010 and 2009, respectively. The total grant-date fair value of time-based shares that vested was $1 million, $10 million and $39 million for the years ended December 31, 2011, 2010 and 2009, respectively.

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, 2011:

	Number of units		Weighted-average grant-date fair value per share
Unvested at January 1, 2011	1,844,784		$	75.23
Granted	1,090,747		77.55
Vested	(832,252	)	78.97
Forfeited	(163,439	)	76.94
Unvested at December 31, 2011	1,939,840		$	74.78

The total grant-date fair value of the time-based units vested during the year ended December 31, 2011 was $66 million.

There were 1,055,367 and 1,287,893 time-based units granted during the years ended December 31, 2010 and 2009, respectively. The weighted-average grant-date fair value of time-based units granted was $76.83 and $60.53 per share for the years ended December 31, 2010 and 2009, respectively. There were 559,339 and 282,543 time-based units that vested during the years ended December 31, 2010 and 2009, respectively. The total grant-date fair value of deferred units that vested was $45 million and $33 million for the years ended December 31, 2010 and 2009, respectively.

SARs—The following table summarizes share-settled SARs activity under our incentive plans during the year ended December 31, 2011:

	Number of awards		Weighted-average exercise price per share		Weighted-average remaining contractual term (years)	Aggregate intrinsic value (in millions)
Outstanding at January 1, 2011	189,139		$	93.28	5.76	$	—
Exercised	(1,400	)	77.73		—	—
Forfeited	(7,768	)	105.57		—	—
Outstanding at December 31, 2011	179,971		$	92.87	4.66	$	—

Vested and exercisable at December 31, 2011	179,971		$	92.87	4.66	$	—

At January 1 and December 31, 2011, 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. We did not grant share-settled SARs during the years ended December 31, 2011, 2010, and 2009. There were no share-settled SARs exercised during the year ended December 31, 2010. There were 224 share-settled SARs exercised with a total pretax intrinsic value of zero during the year ended December 31, 2009. There were no unvested share-settled SARs outstanding as of December 31, 2011, 2010 and 2009.

Performance-Based Awards

Stock options—We grant performance-based stock options (“performance-based options”) that can 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 vested and unvested performance-based option activity under our incentive plans during the year ended December 31, 2011:

	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, 2011	179,262	$	75.30	5.22	$	—
Outstanding at December 31, 2011	179,262	$	75.30	4.23	$	—

Vested and exercisable at December 31, 2011	179,262	$	75.30	4.23	$	—

At December 31, 2011, 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. We did not grant performance-based options during the years ended December 31, 2011, 2010 and 2009. There were no performance-based options exercised during the years ended December 31, 2011, 2010 and 2009. There were no unvested performance-based stock options outstanding as of December 31, 2011, 2010 and 2009.

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, 2011:

	Number of units		Weighted-average grant-date fair value per share
Unvested at January 1, 2011	422,906		$	89.14
Granted	98,797		78.69
Forfeited	(105,756	)	121.89
Unvested at December 31, 2011	415,947		$	75.98

There were 122,934 and 285,012 market-based units granted with a weighted-average grant-date fair value of $82.55 and $75.98 per share during the years ended December 31, 2010 and 2009, respectively. No market-based units vested in the years ended December 31, 2011, 2010 and 2009.

Supplemental Balance Sheet Information

12 Months Ended

Dec. 31, 2011

Supplemental Balance Sheet Information

Supplemental Balance Sheet Information

Note 19—Supplemental Balance Sheet Information

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

	December 31,
	2011		2010
Other current liabilities
Accrued payroll and employee benefits	$	340	$	270
Distribution payable	278		—
Deferred revenue	181		134
Deferred revenue of consolidated variable interest entities	16		16
Accrued taxes, other than income	127		126
Accrued interest	132		97
Unearned income	2		15
Contingent liabilities	1,229		164
Other	45		61
Total other current liabilities	$	2,350	$	883

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

	December 31,
	2011		2010
Other long-term liabilities
Long-term income taxes payable	$	729	$	675
Accrued pension liabilities	579		426
Deferred revenue	244		302
Deferred revenue of consolidated variable interest entities	85		91
Drilling contract intangibles	103		152
Accrued retiree life insurance and medical benefits	49		52
Other	114		93
Total other long-term liabilities	$	1,903	$	1,791

Supplemental Cash Flow Information

12 Months Ended

Dec. 31, 2011

Supplemental Cash Flow Information

Supplemental Cash Flow Information

Note 20—Supplemental Cash Flow Information

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

	Years ended December 31,
	2011			2010			2009
Changes in operating assets and liabilities
Decrease (increase) in accounts receivable	$	(174	)	$	386		$	504
Increase in other current assets	(73		)	(75		)	(50		)
Increase in other assets	(5		)	(40		)	(30		)
Increase (decrease) in accounts payable and other current liabilities	978			227			(60		)
Decrease in other long-term liabilities	(34		)	(52		)	(7		)
Change in income taxes receivable / payable, net	53			(37		)	77
	$	745		$	409		$	434

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

	Years ended December 31,
	2011		2010		2009
Certain cash operating activities
Cash payments for interest	$	626	$	641	$	683
Cash payments for income taxes	338		493		663

Non-cash investing and financing activities
Capital expenditures, accrued at end of period (a)	$	68	$	69	$	139
Asset capitalized under capital leases (b)	—		—		716
Non-cash proceeds received for the sale of assets (c)	—		134		—

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

(b) On August 4, 2009, we accepted delivery of Petrobras 10000 and recorded non-cash additions of $716 million to property and equipment, net along with a corresponding increase to long-term debt. See Note 12—Debt and Note 15—Commitments and Contingencies.

(c) 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 face value amount of $165 million. We recognized the notes receivable at their estimated fair value, in the aggregate amount of $134 million, measured at the time of the sale. See Note 23—Variable Interest Entities and Note 10—Drilling Fleet.

Fair Value of Financial Instruments

12 Months Ended

Dec. 31, 2011

Fair Value of Financial Instruments

Fair Value of Financial Instruments

Note 21—Fair Value of Financial Instruments

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

	December 31, 2011				December 31, 2010
	Carrying amount		Fair value		Carrying amount		Fair value
Cash and cash equivalents	$	4,017	$	4,017	$	3,394	$	3,394
Accounts receivable	2,049		2,049		1,653		1,653
Notes receivable and working capital loan receivable	139		139		115		115
Restricted cash investments	928		975		47		47
Long-term debt, including current maturities	12,698		13,074		10,271		10,562
Long-term debt of consolidated variable interest entities, including current maturities	838		838		950		964
Derivative instruments, assets	36		36		21		21
Derivative instruments, liabilities	38		38		13		13

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.

Accounts receivable—The carrying amount, net of valuation allowance, approximates fair value because of the short maturities of those instruments.

Notes receivable and working capital loan receivable—The carrying amount represents the amortized cost of our investment, which approximates the estimated fair value. We measured the estimated fair value using significant unobservable inputs, including the credit rating of the borrower. At December 31, 2011, the aggregate carrying amount of our notes receivable and working capital loan receivable was $139 million, including $37 million and $102 million recorded in other current assets and other assets, respectively. At December 31, 2010, the aggregate carrying amount of our notes receivable and working capital loan receivable was $115 million, including $4 million and $111 million recorded in other current assets and other assets, respectively.

Restricted cash investments—For the Aker Restricted Cash Investment, acquired in our acquisition of Aker Drilling, the carrying amount of $889 million at December 31, 2011 represents the amortized cost of our investment. The fair value of our Aker Restricted Cash Investments was measured using significant other observable inputs. In the case of the restricted cash investments for the TPDI Credit Facilities and the ADDCL Credit Facilities, the carrying amount approximates fair value due to the short term nature of the instruments in which the restricted cash investments are held. The aggregate carrying amount of the restricted cash investments for the TPDI Credit Facilities and the ADDCL Credit Facilities was $39 million at December 31, 2011 and 2010.

Debt—The fair value of our fixed-rate debt is measured using significant other observable inputs. The carrying amounts 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.

Derivative instruments—The carrying amount of our derivative instruments represents the estimated fair value, measured using significant other observable inputs.

- Definition

This item represents the complete disclosure regarding 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 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 Company 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 risk is 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+ Details

Financial Instruments and Risk Concentration

12 Months Ended

Dec. 31, 2011

Financial Instruments and Risk Concentration

Financial Instruments and Risk Concentration

Note 22—Financial Instruments and 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.

In connection with our acquisition of Aker Drilling, we assumed certain interest rate swaps that are not designated as hedging instruments for accounting purposes. We record these undesignated interest rate swaps at fair value and record changes to the fair value in current period earnings as an adjustment to interest expense.

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, 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. At December 31, 2010, we had no outstanding currency exchange derivative instruments.

Credit risk—Financial instruments that potentially subject us to concentrations of credit risk are primarily cash and cash equivalents, short-term investments and trade receivables. It is our practice to place 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 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 required 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.

Labor agreements—We require highly skilled personnel to operate our drilling units. We conduct extensive personnel recruiting, training and safety programs. At December 31, 2011, we had approximately 18,700 employees, including approximately 1,850 persons engaged through contract labor providers. Some of our employees working in Angola, the U.K., Norway and Australia, 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.

Variable Interest Entities

12 Months Ended

Dec. 31, 2011

Variable Interest Entities

Variable Interest Entities

Note 23—Variable Interest Entities

Consolidated variable interest entities—TPDI and ADDCL, joint venture companies in which we hold interests, were formed to own and operate certain ultra-deepwater drillships. We have determined that each of these joint venture companies meets the criteria of a variable interest entity for accounting purposes because its equity at risk is insufficient to permit it to carry on its activities without additional subordinated financial support from us. We have also determined, in each case, that we are the primary beneficiary for accounting purposes since (a) we have 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 have 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 consolidate TPDI and ADDCL in our consolidated financial statements, we eliminate intercompany transactions, and we present the interests that are not owned by us as noncontrolling interest on our consolidated balance sheets. The carrying amounts associated with these joint venture companies, after eliminating the effect of intercompany transactions, were as follows (in millions):

	December 31, 2011						December 31, 2010
	Assets		Liabilities		Net carrying amount		Assets		Liabilities		Net carrying amount
Variable interest entity
TPDI	$	1,562	$	673	$	889	$	1,598	$	763	$	835
ADDCL	930		334		596		864		345		519
Total	$	2,492	$	1,007	$	1,485	$	2,462	$	1,108	$	1,354

At December 31, 2011 and 2010, 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 $2,165 million and $2,191 million, respectively. See Note 12—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 (see Note 10—Drilling Fleet). The notes receivable, originally issued in exchange for and secured by two drilling units, have stated interest rates of nine percent and are payable in scheduled quarterly installments of principal and interest through maturity in January 2015. Additionally, we provide Awilco with a working capital loan, also secured by the drilling units, that has a stated interest rate of 10 percent and a maximum borrowing amount of $35 million. We evaluate the credit quality and financial condition of Awilco quarterly. The aggregate carrying amount of the notes receivable was $110 million and $109 million at December 31, 2011 and 2010, respectively. The aggregate carrying amount of the working capital loan receivable was $29 million and $6 million at December 31, 2011 and 2010, respectively.

During the year ended December 31, 2011, we determined that Awilco no longer met the definition of a variable interest entity following a private placement of its shares and the listing of its shares on the Oslo Stock Exchange and the successful marketing of its two drilling units.

- Definition

Disclosure of variable interest entities (VIE), including, but not limited to the nature, purpose, size, and activities of the VIE, the carrying amount and classification of consolidated assets that are collateral for the VIE's obligations, lack of recourse if creditors (or beneficial interest holders) of a consolidated VIE have no recourse to the general credit of the primary beneficiary. An enterprise that holds a significant variable interest in a VIE but is not the primary beneficiary may disclose the nature of its involvement with the VIE and when that involvement began, the nature, purpose, size, and activities of the VIE and the enterprise's maximum exposure to loss as a result of its involvement with the VIE.

+ References+ Details

Related Party Transactions

12 Months Ended

Dec. 31, 2011

Related Party Transactions

Related Party Transactions

Note 24—Related Party Transactions

Quantum Pacific Management Limited—We hold a 50 percent interest in TPDI, a consolidated British Virgin Islands joint venture company formed to own and operate Dhirubhai Deepwater KG1 and Dhirubhai Deepwater KG2. Quantum holds the remaining 50 percent interest. Quantum has the unilateral right to exchange its interest in the joint venture for our shares or cash, at an amount based on an appraisal of the fair value of the drillships, subject to certain adjustments.

As of December 31, 2011 and 2010, TPDI had outstanding promissory notes in the aggregate amount of $296 million, of which $148 million was due to Quantum and was included in long-term debt of consolidated variable interest entities on our consolidated balance sheets.

Angco Cayman Limited—We hold a 65 percent interest in ADDCL, a consolidated Cayman Islands joint venture company formed to own and operate Discoverer Luanda. Angco Cayman holds the remaining 35 percent interest in ADDCL. Beginning January 31, 2016, Angco Cayman will have the right to exchange its interest in the joint venture for cash at an amount based on the appraisal of the fair value of the drillship, subject to certain adjustments.

Overseas Drilling Limited—We held a 50 percent interest in ODL, an unconsolidated Cayman Islands joint venture company, which owns Joides Resolution, a coring drillship that was adapted for scientific research. Under a management services agreement with ODL, we provided certain operational and management services through the date of the sale of our interest. We earned $1 million and $2 million for these services in each of the years ended December 31, 2011 and 2010, respectively.

During the year ended December 31, 2011, we completed the sale of our 50 percent ownership interest in ODL to Siem Offshore Inc. In connection with the sale, we received net proceeds of $22 million and recognized a net gain of $13 million ($0.04 per diluted share from continuing operations), recorded in other, net, which had no tax effect.

- Definition

This element may be used for the entire related party transactions disclosure as a single block of text. Disclosure may include: the nature of the relationship(s), a description of the transactions, the amount of the transactions, the effects of any change in the method of establishing the terms of the transaction from the previous period, stated interest rate, expiration date, terms and manner of settlement per the agreement with the related party, and amounts due to or from related parties. If the entity and one or more other entities are under common ownership or management control and this control affects the operating results or financial position, disclosure includes the nature of the control relationship even if there are no transactions between the entities. Disclosure may also include the aggregate amount of current and deferred tax expense for each statement of earnings presented where the entity is a member of a group that files a consolidated tax return, the amount of any tax related balances due to or from affiliates as of the date of each statement of financial position presented, the principal provisions of the method by which the consolidated amount of current and deferred tax expense is allocated to the members of the group and the nature and effect of any changes in that method. 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.

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Operating Segments, Geographic Analysis and Major Customers

12 Months Ended

Dec. 31, 2011

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 business does not meet the quantitative thresholds for determining reportable segments.

Geographic analysis—Operating revenues by country were as follows (in millions):

	Years ended December 31,
	2011		2010		2009
Operating revenues
U.S.	$	1,975	$	2,087	$	2,209
U.K.	1,211		1,183		1,563
Brazil	1,019		1,288		1,108
Other countries (a)	4,937		4,908		6,561
Total operating revenues	$	9,142	$	9,466	$	11,441

(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,
	2011		2010
Long-lived assets
U.S.	$	6,549	$	5,519
Brazil	2,185		2,472
India	1,593		2,632
Other countries (a)	12,202		10,696
Total long-lived assets	$	22,529	$	21,319

(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, 2011 and 2010, we had $8 million and $15 million, respectively, of long-lived assets in Switzerland.

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 years ended December 31, 2011, 2010 and 2009, BP accounted for approximately 10 percent, 10 percent and 12 percent, respectively, of our operating revenues.

Condensed Consolidating Financial Information

12 Months Ended

Dec. 31, 2011

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. has also guaranteed borrowings under the commercial paper program and the Five-Year Revolving Credit Facility. 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, 2011
	Parent Guarantor			Subsidiary Issuer			Other Subsidiaries			Consolidating adjustments			Consolidated

Operating revenues	$	—		$	—		$	9,160		$	(18	)	$	9,142
Cost and expenses	44			4			8,663			(18		)	8,693
Loss on impairment	—			—			(5,229		)	—			(5,229		)
Gain on disposal of assets, net	—			—			4			—			4
Operating loss	(44		)	(4		)	(4,728		)	—			(4,776		)

Other income (expense), net
Interest expense, net	(11		)	(510		)	(56		)	—			(577		)
Equity in earnings	(5,670		)	(5,145		)	18			10,815			18
Other, net	—			9			(108		)	—			(99		)
	(5,681		)	(5,646		)	(146		)	10,815			(658		)
Loss from continuing operations before income tax expense	(5,725		)	(5,650		)	(4,874		)	10,815			(5,434		)
Income tax expense	—			—			395			—			395
Loss from continuing operations	(5,725		)	(5,650		)	(5,269		)	10,815			(5,829		)
Income from discontinued operations, net of tax	—			—			197			—			197

Net loss	(5,725		)	(5,650		)	(5,072		)	10,815			(5,632		)
Net income attributable to noncontrolling interest	—			—			93			—			93
Net loss attributable to controlling interest	$	(5,725	)	$	(5,650	)	$	(5,165	)	$	10,815		$	(5,725	)

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

Operating revenues	$	—		$	—		$	9,481		$	(15	)	$	9,466
Cost and expenses	45			3			6,823			(15		)	6,856
Loss on impairment	—			—			(1,010		)	—			(1,010		)
Gain on disposal of assets, net	—			—			257			—			257
Operating income (loss)	(45		)	(3		)	1,905			—			1,857

Other income (expense), net
Interest income (expense), net	1			(494		)	(51		)	—			(544		)
Equity in earnings	1,005			1,519			8			(2,524		)	8
Other, net	—			(7		)	(24		)	—			(31		)
	1,006			1,018			(67		)	(2,524		)	(567		)
Income from continuing operations before income tax expense	961			1,015			1,838			(2,524		)	1,290
Income tax expense	—			—			336			—			336
Income from continuing operations	961			1,015			1,502			(2,524		)	954
Income from discontinued operations, net of tax	—			—			34			—			34

Net income	961			1,015			1,536			(2,524		)	988
Net income attributable to noncontrolling interest	—			—			27			—			27

Net income attributable to controlling interest	$	961		$	1,015		$	1,509		$	(2,524	)	$	961

	Year ended December 31, 2009
	Parent Guarantor			Subsidiary Issuer			Other Subsidiaries			Consolidating adjustments			Consolidated

Operating revenues	$	—		$	—		$	11,455		$	(14	)	$	11,441
Cost and expenses	26			4			6,692			(14		)	6,708
Loss on impairment	—			—			(334		)	—			(334		)
Loss on disposal of assets, net	—			—			(9		)	—			(9		)
Operating income (loss)	(26		)	(4		)	4,420			—			4,390

Other income (expense), net
Interest income (expense), net	1			(521		)	41			—			(479		)
Equity in earnings	3,206			3,773			6			(6,979		)	6
Other, net	—			(43		)	45			—			2
	3,207			3,209			92			(6,979		)	(471		)
Income from continuing operations before income tax expense	3,181			3,205			4,512			(6,979		)	3,919
Income tax expense	—			—			723			—			723
Income from continuing operations	3,181			3,205			3,789			(6,979		)	3,196
Loss from discontinued operations, net of tax	—			—			(26		)	—			(26		)

Net income	3,181			3,205			3,763			(6,979		)	3,170
Net loss attributable to noncontrolling interest	—			—			(11		)	—			(11		)

Net income attributable to controlling interest	$	3,181		$	3,205		$	3,774		$	(6,979	)	$	3,181

	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		4,493		(1,693		)	3,592
Total current assets	11		3,577		5,714		(1,693		)	7,609

Property and equipment, net	1		—		22,528		—			22,529
Goodwill	—		—		3,205		—			3,205
Investment in affiliates	16,503		27,582		—		(44,085		)	—
Other assets	—		1,368		17,908		(17,531		)	1,745
Total assets	16,515		32,527		49,355		(63,309		)	35,088

Liabilities and equity
Debt due within one year	—		1,693		346		—			2,039
Other current liabilities	294		367		4,351		(1,693		)	3,319
Total current liabilities	294		2,060		4,697		(1,693		)	5,358

Long-term debt	495		14,308		14,225		(17,531		)	11,497
Other long-term liabilities	25		439		1,962		—			2,426
Total long-term liabilities	520		14,747		16,187		(17,531		)	13,923

Commitments and contingencies
Redeemable noncontrolling interest	—		—		116		—			116

Total equity	15,701		15,720		28,355		(44,085		)	15,691
Total liabilities and equity	$	16,515	$	32,527	$	49,355	$	(63,309	)	$	35,088

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

Assets
Cash and cash equivalents	$	38	$	2,041	$	1,315	$	—		$	3,394
Other current assets	12		788		3,189		(1,188		)	2,801
Total current assets	50		2,829		4,504		(1,188		)	6,195

Property and equipment, net	1		—		21,318		—			21,319
Goodwill	—		—		8,132		—			8,132
Investment in affiliates	21,373		33,473		19		(54,846		)	19
Other assets	—		1,017		14,001		(13,872		)	1,146
Total assets	21,424		37,319		47,974		(69,906		)	36,811

Liabilities and equity
Debt due within one year	—		1,891		121		—			2,012
Other current liabilities	21		444		2,547		(1,188		)	1,824
Total current liabilities	21		2,335		2,668		(1,188		)	3,836

Long-term debt	—		13,354		9,727		(13,872		)	9,209
Other long-term liabilities	20		292		2,054		—			2,366
Total long-term liabilities	20		13,646		11,781		(13,872		)	11,575

Commitments and contingencies
Redeemable noncontrolling interest	—		—		25		—			25

Total equity	21,383		21,338		33,500		(54,846		)	21,375
Total liabilities and equity	$	21,424	$	37,319	$	47,974	$	(69,906	)	$	36,811

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

Cash flows from operating activities	$	(52	)	$	503		$	1,334		$	—		$	1,785

Cash flows from investing activities
Capital expenditures	—			—			(1,020		)	—			(1,020		)
Investment in business combination, net of cash acquired	—			—			(1,246		)	—			(1,246		)
Proceeds from disposal of assets, net	—			—			177			—			177
Proceeds from disposal of discontinued operations, net	—			—			284			—			284
Investing activities with affiliates, net	(875		)	(325		)	(693		)	1,893			—
Other, net	—			(23		)	(68		)	—			(91		)
Net cash provided by (used in) investing activities	(875		)	(348		)	(2,566		)	1,893			(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 share issuance, net	1,211			—			—			—			1,211
Distribution of qualifying additional paid-in capital	(763		)	—			—			—			(763		)
Financing activities with affiliates, net	495			43			1,355			(1,893		)	—
Other, net	(57		)	(35		)	(64		)	—			(156		)
Net cash provided by (used in) financing activities	892			597			1,138			(1,893		)	734

Net increase (decrease) in cash and cash equivalents	(35		)	752			(94		)	—			623
Cash and cash equivalents at beginning of period	38			2,041			1,315			—			3,394
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	)	$	4,337		$	—		$	3,946

Cash flows from investing activities
Capital expenditures	(4		)	—			(1,387		)	—			(1,391		)
Proceeds from insurance recoveries for loss of drilling unit	—			—			560			—			560
Proceeds from disposal of assets, net	—			—			60			—			60
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			307			—			2,264
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		$	1,315		$	—		$	3,394

	Year ended December 31, 2009
	Parent Guarantor			Subsidiary Issuer			Other Subsidiaries			Consolidating adjustments			Consolidated

Cash flows from operating activities	$	(24	)	$	(429	)	$	6,051		$	—		$	5,598

Cash flows from investing activities
Capital expenditures	(1		)	—			(3,040		)	—			(3,041		)
Investing activities with affiliates, net	29			1,667			(2,068		)	372			—
Other, net	—			—			347			—			347
Net cash provided by (used in) investing activities	28			1,667			(4,761		)	372			(2,694		)

Cash flows from financing activities
Changes in short-term borrowings, net	—			(382		)	—			—			(382		)
Proceeds from debt	—			—			514			—			514
Repayments of debt	—			(2,865		)	(6		)	—			(2,871		)
Financing activities with affiliates, net	—			2,008			(1,636		)	(372		)	—
Other, net	1			4			(3		)	—			2
Net cash provided by (used in) financing activities	1			(1,235		)	(1,131		)	(372		)	(2,737		)

Net increase in cash and cash equivalents	5			3			159			—			167
Cash and cash equivalents at beginning of period	—			114			849			—			963
Cash and cash equivalents at end of period	$	5		$	117		$	1,008		$	—		$	1,130

- Definition

Text block that encapsulates the detailed table comprising the condensed financial statements (balance sheet, income statement and statement of cash flows), normally using the registrant (parent) as the sole domain member. If condensed consolidating financial statements are being presented, other domain members (in addition to parent) such as guarantor subsidiaries, non-guarantor subsidiaries, and the consolidation eliminations, will be included in order that the respective monetary amounts for each of the domains will aggregate to the respective amounts on the consolidated financial statements. The line items are the various captions used to compile the condensed financial statements. Using extensions, most, if not all, of the elements representing condensed financial statement captions will be the same as those used for the consolidated financial statements captions.

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Quarterly Results (Unaudited)

12 Months Ended

Dec. 31, 2011

Quarterly Results (Unaudited)

Quarterly Results (Unaudited)

Note 27—Quarterly Results (Unaudited)

Shown below are selected unaudited quarterly data. Amounts are rounded for consistency in presentation with no effect to the results of operations previously reported on Form 10-Q or Form 10-K.

	Three months ended
	March 31,		June 30,		September 30,			December 31,
	(In millions, except per share data)
2011
Operating revenues	$	2,144	$	2,334	$	2,242		$	2,422
Operating income (loss) (a)	372		391		268			(5,807		)
Income (loss) from continuing operations	164		162		(53		)	(6,102		)
Net income (loss) attributable to controlling interest (a) (b)	310		155		(71		)	(6,119		)
Per share earnings (loss) from continuing operations
Basic	$	0.42	$	0.47	$	(0.20	)	$	(18.70	)
Diluted	$	0.42	$	0.47	$	(0.20	)	$	(18.70	)
Weighted-average shares outstanding
Basic	319		320		320			329
Diluted	320		320		320			329

2010
Operating revenues	$	2,579	$	2,479	$	2,281		$	2,127
Operating income (loss) (c)	942		949		634			(668		)
Income (loss) from continuing operations	683		712		363			(804		)
Net income (loss) attributable to controlling interest (c)	677		715		368			(799		)
Per share earnings (loss) from continuing operations
Basic	$	2.09	$	2.20	$	1.10		$	(2.53	)
Diluted	$	2.08	$	2.20	$	1.10		$	(2.53	)
Weighted-average shares outstanding
Basic	321		319		319			319
Diluted	322		320		319			319

(a) Third quarter included a loss of $78 million on 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 5—Impairments, Note 10—Drilling Fleet and Note 15—Commitments and Contingencies.

(b) First, third and fourth quarters included gains (losses) on disposal of discontinued operations in the amount of $173 million, $(4) million and $12 million, respectively.

(c) Second quarter included gain of $267 million on the loss of Deepwater Horizon. Fourth quarter included loss of $1.0 billion on impairment of long-lived assets. See Note 5—Impairments and Note 10—Drilling Fleet.

- Definition

This element can be used to disclose the entire quarterly financial data disclosure in the annual financial statements as a single block of text. The disclosure includes a tabular presentation of financial information for each fiscal quarter for the current and previous year, including revenues, gross profit, income (loss) before extraordinary items and cumulative effect of a change in accounting principle 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. Alternatively, the details of this disclosure can be reported using the elements in this group, or by using other taxonomy elements and applying the appropriate quarterly date and period contexts when creating an instance document. For example, the element for "Interest and Dividend Income, Operating" may be used by financial institutions from the Statement of Income, applying the appropriate quarterly date and period context when creating an instance document.

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Subsequent Events

12 Months Ended

Dec. 31, 2011

Subsequent Events

Subsequent Events

Note 28—Subsequent Events

Debt—Subsequent to December 31, 2011, we redeemed the remaining $30 million aggregate principal amount of the Series B Convertible Senior Notes.

Drilling fleet—Subsequent to December 31, 2011, we entered into agreements to sell the Standard Jackups, GSF Rig 136, Transocean Nordic and Transocean Shelf Explorer, and we reclassified to assets held for sale the rigs and related equipment, having an aggregate carrying amount of $59 million.

Discontinued operations—Subsequent to December 31, 2011, we entered into an agreement to sell the assets of Challenger Minerals Inc.

U.S. tax investigations—Subsequent to December 31, 2011, 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. These items would result in net adjustments of approximately $473 million of additional taxes, excluding interest. An unfavorable outcome on these adjustments 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 these positions with respect to subsequent years and were successful in such assertions, 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 returns are materially correct as filed, and we intend to continue to vigorously defend against all such claims.

Norway tax investigations—In January 2012, the Norwegian authorities supplemented the previously issued criminal indictments by issuing a financial claim of approximately $315 million, jointly and severally, against our two subsidiaries, the two external advisors and the external tax attorney. This compensation claim directly overlaps with an existing civil tax assessment and does not represent any incremental financial exposure to us. In February 2012, the authorities dropped the previously existing tax assessment.

Macondo well incident—On January 26, 2012, the MDL Court ruled that BP is required 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 court also held that BP does not owe us indemnity to the extent that we are held liable for punitive damages or civil penalties under the Clean Water Act. The court deferred ruling on BP’s argument that we breached the drilling contract or materially increased BP’s risk or prejudiced its rights so as to impair BP’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 disallows contractual indemnity for criminal fines and penalties as against public policy.

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 Clean Water Act, and that we therefore are not liable for such discharges as an owner of the vessel under the Clean Water Act. However, the court ruled that the issue of whether we could be held liable for such discharge under the Clean Water Act 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.

Schedule II - Valuation and Qualifying Accounts

12 Months Ended

Dec. 31, 2011

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, 2009
Reserves and allowances deducted from asset accounts:
Allowance for doubtful accounts receivable	$	114	$	27	$	—	$	76	(a)	$	65
Allowance for obsolete materials and supplies	49		17		—		—			66
Valuation allowance on deferred tax assets	111		49		—		—			160

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

(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

Dec. 31, 2011

Significant Accounting Policies

Accounting estimates

Fair value measurements

Consolidation

Business combination

Operating revenues and expenses

Contract drilling intangible revenues

Other revenues

Share-based compensation

Capitalized interest

Foreign currency

Income taxes

Cash and cash equivalents

Allowance for doubtful accounts

Materials and supplies

Assets held for sale

Property and equipment

Long-lived assets and definite-lived intangible assets

Goodwill and other indefinite-lived intangible assets

Derivatives and hedging

Pension and other postretirement benefits

Contingent liabilities

Reclassifications

Subsequent events

Subsequent events—We evaluate subsequent events through the time of our filing on the date we issue our financial statements. See Note 28—Subsequent Events.

Business Combination (Tables)

12 Months Ended

Dec. 31, 2011

Business Combination

Schedule of pro forma combined operating results

	Years ended December 31,
	2011			2010
Operating revenues	$	9,454		$	9,797
Operating income (loss)	(4,628		)	1,975
Income (loss) from continuing operations	(5,806		)	999

Per share earnings (loss) from continuing operations
Basic	$	(18.33	)	$	3.02
Diluted	$	(18.33	)	$	3.02

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2011

Income Taxes

Components of the provision (benefit) for income taxes

	Years ended December 31,
	2011			2010			2009
Current tax expense	$	426		$	450		$	738
Deferred tax expense (benefit)	(31		)	(114		)	(15		)
Income tax expense	$	395		$	336		$	723

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,
	2011			2010			2009
Income tax expense at the Swiss federal statutory rate	$	(425	)	$	101		$	307
Taxes on earnings subject to rates greater than the Swiss federal statutory rate	285			107			288
Taxes on impairment loss subject to rates less than the Swiss federal statutory rate	409			79			—
Taxes on asset sales subject to rates less than the Swiss federal statutory rate	(16		)	—			—
Taxes on litigation matters subject to rates less than the Swiss federal statutory rate	78			—			—
Changes in unrecognized tax benefits, net	62			71			135
Change in valuation allowance	19			4			49
Benefit from foreign tax credits	(28		)	(23		)	(49		)
Taxes on asset acquisition costs at rates lower than the Swiss federal statutory rate	8			—			—
Other, net	3			(3		)	(7		)
Income tax expense	$	395		$	336		$	723

Significant components of deferred tax assets and liabilities

	December 31,
	2011			2010
Deferred tax assets
Drilling contract intangibles	$	2		$	6
Net operating loss carryforwards	341			184
Tax credit carryforwards	45			29
Accrued payroll expenses not currently deductible	77			72
Deferred income	67			84
Valuation allowance	(183		)	(164		)
Other	81			61
Total deferred tax assets	430			272

Deferred tax liabilities
Depreciation and amortization	(749		)	(680		)
Drilling management services intangibles	(25		)	(26		)
Other	(37		)	(26		)
Total deferred tax liabilities	(811		)	(732		)

Net deferred tax liabilities	$	(381	)	$	(460	)

Valuation allowance for non-current deferred tax assets

	December 31,
	2011		2010
Valuation allowance for non-current deferred tax assets	$	183	$	164

Reconciliation of unrecognized tax benefits, excluding interest and penalties

	Years ended December 31,
	2011			2010			2009
Balance, beginning of period	$	485		$	460		$	372
Additions for current year tax positions	45			46			64
Additions for prior year tax positions	23			9			62
Reductions for prior year tax positions	—			(11		)	(22		)
Settlements	(42		)	(17		)	(3		)
Reductions related to statute of limitation expirations	(2		)	(2		)	(13		)
Balance, end of period	$	509		$	485		$	460

Schedule of unrecognized tax benefits, including related interest and penalties

	December 31,
	2011		2010
Unrecognized tax benefits, excluding interest and penalties	$	509	$	485
Interest and penalties	272		235
Unrecognized tax benefits, including interest and penalties	$	781	$	720

- Definition

The disclosure required for 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.

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Discontinued Operations (Tables)

12 Months Ended

Dec. 31, 2011

Discontinued Operations

Summarized results of discontinued operations

	Years ended December 31,
	2011			2010			2009
Operating revenues	$	62		$	110		$	115
Costs and expenses	(55		)	(99		)	(110		)
Loss on impairment (a)	(10		)	(2		)	—
Gain on disposal of discontinued operations, net	181			—			—
Income from discontinued operations before income tax expense	178			9			5
Income tax benefit (expense)	19			25			(31		)

Income (loss) from discontinued operations, net of tax	$	197		$	34		$	(26	)

Assets and liabilities of discontinued operations

	December 31,
	2011		2010
Assets
Oil and gas properties, net	$	24	$	—
Other related assets	2		—
Assets held for sale	$	26	$	—

Accounts receivable	$	6	$	22
Other assets	25		17
Other current assets	$	31	$	39

Rig and related equipment, net	$	—	$	86
Oil and gas properties, net	—		53
Other assets	$	—	$	139

Liabilities
Accounts payable	$	3	$	15
Other liabilities	14		13
Other current liabilities	$	17	$	28

Asset retirement obligation	$	—	$	9
Deferred taxes	—		19
Other long-term liabilities	$	—	$	28

Earnings (Loss) Per Share (Tables)

12 Months Ended

Dec. 31, 2011

Earnings (Loss) Per Share

Earnings Per Share

	Years ended December 31,
	2011						2010						2009
	Basic			Diluted			Basic			Diluted			Basic			Diluted
Numerator for earnings per share
Income (loss) from continuing operations attributable to controlling interest	$	(5,922	)	$	(5,922	)	$	927		$	927		$	3,207		$	3,207
Undistributed earnings allocable to participating securities	—			—			(5		)	(5		)	(18		)	(18		)
Income (loss) from continuing operations available to shareholders	$	(5,922	)	$	(5,922	)	$	922		$	922		$	3,189		$	3,189

Denominator for earnings per share
Weighted-average shares outstanding	322			322			320			320			320			320
Effect of stock options and other share-based awards	—			—			—			—			—			1
Weighted-average shares for per share calculation	322			322			320			320			320			321

Per share earnings (loss) from continuing operations	$	(18.40	)	$	(18.40	)	$	2.88		$	2.88		$	9.95		$	9.92

Other Comprehensive Income (Tables)

12 Months Ended

Dec. 31, 2011

Other Comprehensive Income

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

	Years ended December 31,
	2011									2010									2009
	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	$	(204	)	$	—		$	(204	)	$	(8	)	$	—		$	(8	)	$	37		$	—	$	37
Unrecognized gain (loss) on derivative instruments	3			(16		)	(13		)	(10		)	(19		)	(29		)	(4		)	2		(2		)
Unrecognized loss on marketable securities	(13		)	—			(13		)	—			—			—			—			—		—
Recognized components of net periodic benefit costs	25			—			25			16			—			16			24			—		24
Recognized (gain) loss on derivative instruments	(1		)	12			11			14			(2		)	12			3			3		6
Recognized loss on marketable securities	13			—			13			—			—			—			1			—		1

Other comprehensive income (loss) before income taxes	(177		)	(4		)	(181		)	12			(21		)	(9		)	61			5		66
Income taxes related to other comprehensive income	13			—			13			(9		)	—			(9		)	24			—		24
Other comprehensive income (loss), net of tax	$	(164	)	$	(4	)	$	(168	)	$	3		$	(21	)	$	(18	)	$	85		$	5	$	90

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

Schedule of the components of accumulated other comprehensive income (loss), net of tax

	December 31, 2011									December 31, 2010
	Controlling interest			Non- controlling interest			Redeemable non- controlling interest			Controlling interest			Non- controlling interest			Redeemable non- controlling interest
Unrecognized components of net periodic benefit costs (a)	$	(501	)	$	—		$	—		$	(335	)	$	—		$	—
Unrecognized gain (loss) on derivative instruments	7			(3		)	(17		)	5			(3		)	(13		)
Unrecognized loss on marketable securities	(2		)	—			—			(2		)	—			—
Accumulated other comprehensive income (loss)	$	(496	)	$	(3	)	$	(17	)	$	(332	)	$	(3	)	$	(13	)

(a) Amounts are net of income tax effect of $49 million and $36 million for December 31, 2011 and 2010, respectively.

Drilling Fleet (Tables)

12 Months Ended

Dec. 31, 2011

Drilling Fleet

Actual capital expenditures and other capital additions, including capitalized interest

	Years ended December 31,
	2011		2010		2009		2008 - 2006		Total
Ultra-Deepwater Floater TBN1 (a)	$	138	$	—	$	—	$	—	$	138
Ultra-Deepwater Floater TBN2 (a)	137		—		—		—		137
Transocean Honor (b)	119		97		—		—		216
Transocean Siam Driller (c)	110		9		—		—		119
Transocean Andaman (c)	110		9		—		—		119
Transocean Ao Thai (d)	79		—		—		—		79
Deepwater Champion (e) (f)	43		206		263		264		776
Discoverer Luanda (f) (g)	12		174		220		315		721
Discoverer India (f)	6		203		291		250		750
Dhirubhai Deepwater KG2 (f) (h)	—		36		371		270		677
Development Driller III (e) (f)	—		24		117		483		624
Discoverer Inspiration (f)	—		12		224		443		679
Discoverer Americas (f)	—		6		148		478		632
Discoverer Clear Leader (f)	—		6		115		516		637
Petrobras 10000 (f) (i)	—		6		735		—		741
Dhirubhai Deepwater KG1 (f) (h)	—		—		295		384		679
Sedco 700-series upgrades (f)	—		—		71		520		591
Capitalized interest	39		89		182		240		550
Mobilization costs	20		89		155		—		264
Total	$	813	$	966	$	3,187	$	4,163	$	9,129

(f) The accumulated construction costs of these rigs are no longer included in construction work in progress, as their construction projects had been completed as of December 31, 2011.

Goodwill and Other Intangible Assets (Tables)

12 Months Ended

Dec. 31, 2011

Goodwill and Other Intangible Assets

Schedule of gross carrying amounts of goodwill and accumulated impairment

	Year ended December 31, 2011								Year ended December 31, 2010
	Gross carrying amount		Accumulated impairment			Net carrying amount			Gross carrying amount		Accumulated impairment			Net carrying amount
Contract drilling services
Balance, beginning of period	$	10,626	$	(2,494	)	$	8,132		$	10,626	$	(2,494	)	$	8,132
Impairment	—		(5,200		)	(5,200		)	—		—			—
Business combination	273		—			273			—		—			—
Balance, end of period	10,899		(7,694		)	3,205			10,626		(2,494		)	8,132

Drilling management services
Balance, beginning of period	176		(176		)	—			176		(176		)	—
Balance, end of period	176		(176		)	—			176		(176		)	—

Total goodwill
Balance, beginning of period	10,802		(2,670		)	8,132			10,802		(2,670		)	8,132
Impairment	—		(5,200		)	(5,200		)	—		—			—
Business combination	273		—			273			—		—			—
Balance, end of period	$	11,075	$	(7,870	)	$	3,205		$	10,802	$	(2,670	)	$	8,132

Schedule of carrying value of ADTI trade name

	Year ended December 31, 2011							Year ended December 31, 2010
	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
Balance, end of period	$	76	$	(37	)	$	39	$	76	$	(37	)	$	39

Schedule of carrying amounts of definite-lived intangible asset and intangible liabilities

	Year ended December 31, 2011								Year ended December 31, 2010
	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	$	(185	)	$	6		$	191	$	(167	)	$	24
Amortization	—		(6		)	(6		)	—		(18		)	(18		)
Balance, end of period	191		(191		)	—			191		(185		)	6

Customer relationships
Balance, beginning of period	148		(89		)	59			148		(84		)	64
Amortization	—		(5		)	(5		)	—		(5		)	(5		)
Balance, end of period	148		(94		)	54			148		(89		)	59

Total definite-lived intangible assets
Balance, beginning of period	339		(274		)	65			339		(251		)	88
Amortization	—		(11		)	(11		)	—		(23		)	(23		)
Balance, end of period	$	339	(285		)	54			$	339	$	(274	)	$	65

Drilling contract intangible liabilities
Balance, beginning of period	$	1,494	$	(1,342	)	$	152		$	1,494	$	(1,226	)	$	268
Amortization	—		(51		)	(51		)	—		(116		)	(116		)
Balance, end of period	$	1,494	(1,393		)	101			$	1,494	$	(1,342	)	$	152

Schedule of estimated net future amortization related to intangible assets and liabilities

Years ending December 31,	Drilling contract intangibles			Customer relationships
2012	$	(41	)	$	5
2013	(25		)	5
2014	(15		)	5
2015	(14		)	5
2016	(6		)	5
Thereafter	—			29
Total intangible assets (liabilities), net	$	(101	)	$	54

Debt (Tables)

12 Months Ended

Dec. 31, 2011

Debt

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

	December 31, 2011						December 31, 2010
	Transocean Ltd. and subsidiaries		Consolidated variable interest entities		Consolidated total		Transocean Ltd. and subsidiaries		Consolidated variable interest entities		Consolidated total
ODL Loan Facility	$	—	$	—	$	—	$	10	$	—	$	10
Commercial paper program (a)	—		—		—		88		—		88
6.625% Notes due April 2011 (a)	—		—		—		167		—		167
5% Notes due February 2013	253		—		253		255		—		255
5.25% Senior Notes due March 2013 (a)	507		—		507		511		—		511
TPDI Credit Facilities due March 2015	—		473		473		—		560		560
4.95% Senior Notes due November 2015 (a)	1,120		—		1,120		1,099		—		1,099
Aker Revolving Credit and Term Loan Facility due December 2015	594		—		594		—		—		—
5.05% Senior Notes due December 2016 (a)	999		—		999		—		—		—
Callable Bonds due February 2016	267		—		267		—		—		—
ADDCL Credit Facilities due December 2017	—		217		217		—		242		242
Eksportfinans Loans due January 2018	884		—		884		—		—		—
6.00% Senior Notes due March 2018 (a)	998		—		998		997		—		997
7.375% Senior Notes due April 2018 (a)	247		—		247		247		—		247
TPDI Notes due October 2019	—		148		148		—		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		—		—		—
7.45% Notes due April 2027 (a)	97		—		97		96		—		96
8% Debentures due April 2027 (a)	57		—		57		57		—		57
7% Notes due June 2028	311		—		311		313		—		313
Capital lease contract due August 2029	676		—		676		694		—		694
7.5% Notes due April 2031 (a)	598		—		598		598		—		598
1.625% Series A Convertible Senior Notes due December 2037 (a)	—		—		—		11		—		11
1.50% Series B Convertible Senior Notes due December 2037 (a)	30		—		30		1,625		—		1,625
1.50% Series C Convertible Senior Notes due December 2037 (a)	1,663		—		1,663		1,605		—		1,605
6.80% Senior Notes due March 2038 (a)	999		—		999		999		—		999
7.35% Senior Notes due December 2041 (a)	300		—		300		—		—		—
Total debt	12,698		838		13,536		10,271		950		11,221
Less debt due within one year
ODL Loan Facility	—		—		—		10		—		10
Commercial paper program (a)	—		—		—		88		—		88
6.625% Notes due April 2011 (a)	—		—		—		167		—		167
TPDI Credit Facilities due March 2015	—		70		70		—		70		70
Aker Revolving Credit and Term Loan Facility due December 2015	90		—		90		—		—		—
ADDCL Credit Facilities due November 2017	—		27		27		—		25		25
Eksportfinans Loans due January 2018	142		—		142		—		—		—
Capital lease contract due August 2029	17		—		17		16		—		16
1.625% Series A Convertible Senior Notes due December 2037 (a)	—		—		—		11		—		11
1.50% Series B Convertible Senior Notes due December 2037 (a)	30		—		30		1,625		—		1,625
1.50% Series C Convertible Senior Notes due December 2037 (a)	1,663		—		1,663		—		—		—
Total debt due within one year	1,942		97		2,039		1,917		95		2,012
Total long-term debt	$	10,756	$	741	$	11,497	$	8,354	$	855	$	9,209

Scheduled maturities of debt

	Transocean Ltd. and subsidiaries			Consolidated variable interest entities		Consolidated total
Years ending December 31,
2012	$	2,001		$	97	$	2,098
2013	1,002			98		1,100
2014	235			99		334
2015	1,331			322		1,653
2016	1,696			34		1,730
Thereafter	6,450			188		6,638
Total debt, excluding unamortized discounts, premiums and fair value adjustments	12,715			838		13,553
Total unamortized discounts, premiums and fair value adjustments	(17		)	—		(17		)
Total debt	$	12,698		$	838	$	13,536

Carrying amounts of liability components of convertible senior notes

	December 31, 2011							December 31, 2010
	Principal amount		Unamortized discount			Carrying amount		Principal amount		Unamortized discount			Carrying amount
Carrying amount of liability component
Series A Convertible Senior Notes due 2037	$	—	$	—		$	—	$	11	$	—		$	11
Series B Convertible Senior Notes due 2037	30		—			30		1,680		(55		)	1,625
Series C Convertible Senior Notes due 2037	1,722		(59		)	1,663		1,722		(117		)	1,605

Carrying amounts of equity components of convertible senior notes

	December 31,
	2011		2010
Carrying amount of equity component
Series A Convertible Senior Notes due 2037	$	—	$	1
Series B Convertible Senior Notes due 2037	4		210
Series C Convertible Senior Notes due 2037	276		276

Interest expense, excluding amortization of debt issue costs

	Years ended December 31,
	2011		2010		2009
Interest expense
Series A Convertible Senior Notes due 2037	$	—	$	58	$	85
Series B Convertible Senior Notes due 2037	78		98		100
Series C Convertible Senior Notes due 2037	84		98		100

Derivatives and Hedging (Tables)

12 Months Ended

Dec. 31, 2011

Derivatives designated as hedging and not designated as hedging instruments

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

		Year ended December 31,
	Statement of operations classification	2011		2010
Loss associated with effective portion	Interest expense, net of amounts capitalized	$	11	$	12

Derivatives designated as hedging instruments

Derivatives designated as hedging and not designated as hedging instruments

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

		December 31,
	Balance sheet classification	2011		2010
Interest rate swaps, fair value hedges	Other current assets	$	5	$	4
Interest rate swaps, fair value hedges	Other assets	31		17
Interest rate swaps, cash flow hedges	Other long-term liabilities	16		13
Cross-currency swaps, cash flow hedges	Other long-term liabilities	7		—

Derivatives designated as hedging instruments | Interest rate swaps

Derivatives designated as hedging and not designated as hedging instruments

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

	Aggregate notional amount		Weighted average variable rate		Weighted average fixed rate
Interest rate swaps, fair value hedges	$	1,400	3.7	%	5.1	%
Interest rate swaps, cash flow hedges	455		0.6	%	2.3	%

Derivatives designated as hedging instruments | Cross-currency swaps

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
	USD- denominated notional amount		Weighted average fixed rate		NOK- denominated notional amount		Weighted average fixed rate
Cross-currency swaps, cash flow hedges	$	102	8.9	%	NOK	560	11	%

Derivative not designated as hedging instruments | Interest rate swaps

Derivatives designated as hedging and not designated as hedging instruments

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

	Aggregate notional amount		Weighted average variable rate		Weighted average fixed rate
Interest rate swaps not designated as hedging instruments	$	305	0.5	%	4.2	%

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

		December 31,
	Balance sheet classification	2011	2010
Interest rate swaps not designated as hedging instruments	Other long-term liabilities	15	—

Derivative not designated as hedging instruments | Forward exchange contract

Derivatives designated as hedging and not designated as hedging instruments

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

	Aggregate notional amount				Exchange
	Pay		Receive		rate
Forward exchange contract	$	1,120	NOK	6,051	5.4005

Postemployment Benefit Plans (Tables)

12 Months Ended

Dec. 31, 2011

Postemployment Benefit Plans

Schedule of weighted-average assumptions used to determine benefit obligations

	December 31, 2011						December 31, 2010
	U.S. Plans		Non-U.S. Plans		OPEB Plans		U.S. Plans		Non-U.S. Plans		OPEB Plans
Discount rate	4.66	%	4.90	%	4.28	%	5.48	%	5.81	%	4.92	%
Compensation trend rate	4.22	%	4.30	%	n/a		4.24	%	4.65	%	n/a

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

	Year ended December 31, 2011						Year ended December 31, 2010						Year ended December 31, 2009
	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	5.49	%	5.73	%	4.94	%	5.86	%	5.67	%	5.51	%	5.41	%	6.06	%	5.34	%
Expected rate of return	8.49	%	6.42	%	n/a		8.49	%	6.65	%	n/a		8.50	%	6.59	%	n/a
Compensation trend rate	4.24	%	4.62	%	n/a		4.21	%	4.77	%	n/a		4.21	%	4.55	%	n/a
Health care cost trend rate
-initial	n/a		n/a		8.08	%	n/a		n/a		8.00	%	n/a		n/a		8.99	%
-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		2018		n/a		n/a		2016		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

	December 31, 2011						December 31, 2010
	U.S. Plans		Non-U.S. Plans		OPEB Plans		U.S. Plans		Non-U.S. Plans		OPEB Plans
Discount rate	4.66	%	4.90	%	4.28	%	5.48	%	5.81	%	4.92	%
Compensation trend rate	4.22	%	4.30	%	n/a		4.24	%	4.65	%	n/a

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

	Year ended December 31, 2011						Year ended December 31, 2010						Year ended December 31, 2009
	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	5.49	%	5.73	%	4.94	%	5.86	%	5.67	%	5.51	%	5.41	%	6.06	%	5.34	%
Expected rate of return	8.49	%	6.42	%	n/a		8.49	%	6.65	%	n/a		8.50	%	6.59	%	n/a
Compensation trend rate	4.24	%	4.62	%	n/a		4.21	%	4.77	%	n/a		4.21	%	4.55	%	n/a
Health care cost trend rate
-initial	n/a		n/a		8.08	%	n/a		n/a		8.00	%	n/a		n/a		8.99	%
-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		2018		n/a		n/a		2016		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, 2011												Year ended December 31, 2010
	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	$	1,068		$	374		$	56		$	1,498		$	932		$	403		$	54		$	1,389
Assumed projected benefit obligation	—			17			—			17			—			—			—			—
Actuarial (gains) losses, net	128			24			(3		)	149			89			(46		)	2			45
Service cost	43			21			1			65			42			20			1			63
Interest cost	58			22			3			83			54			20			3			77
Foreign currency exchange rate	—			(1		)	—			(1		)	—			(13		)	—			(13		)
Benefits paid	(37		)	(12		)	(5		)	(54		)	(51		)	(14		)	(5		)	(70		)
Participant contributions	—			2			1			3			—			2			1			3
Special termination benefits	—			—			—			—			3			—			—			3
Settlements and curtailments	—			—			—			—			(1		)	2			—			1
Projected benefit obligation, end of period	1,260			447			53			1,760			1,068			374			56			1,498

Change in plan assets
Fair value of plan assets, beginning of period	697			332			—			1,029			594			281			—			875
Fair value of acquired plan assets	—			9			—			9			—			—			—			—
Actual return on plan assets	39			(8		)	—			31			85			29			—			114
Foreign currency exchange rate changes	—			2			—			2			—			(11		)	—			(11		)
Employer contributions	70			29			4			103			69			45			4			118
Participant contributions	—			2			1			3			—			2			1			3
Benefits paid	(37		)	(12		)	(5		)	(54		)	(51		)	(14		)	(5		)	(70		)
Settlement and curtailments	—			(3		)	—			(3		)	—			—			—			—
Fair value of plan assets, end of period	769			351			—			1,120			697			332			—			1,029

Funded status, end of period	$	(491	)	$	(96	)	$	(53	)	$	(640	)	$	(371	)	$	(42	)	$	(56	)	$	(469	)

Balance sheet classification, end of period:
Pension asset, non-current	$	—		$	—		$	—		$	—		$	—		$	(8	)	$	—		$	(8	)
Accrued pension liability, current	3			5			3			11			3			2			4			9
Accrued pension liability, non-current	488			91			50			629			368			48			52			468
Accumulated other comprehensive income (loss) (a)	(437		)	(111		)	(2		)	(550		)	(308		)	(61		)	(2		)	(371		)

(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

	December 31, 2011								December 31, 2010
	U.S. Plans		Non-U.S. Plans		OPEB Plans		Total		U.S. Plans		Non-U.S. Plans		OPEB Plans		Total
Projected benefit obligation	$	1,260	$	447	$	53	$	1,760	$	1,068	$	290	$	56	$	1,414
Fair value of plan assets	769		351		—		1,120		697		248		—		945

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

	December 31, 2011								December 31, 2010
	U.S. Plans		Non-U.S. Plans		OPEB Plans		Total		U.S. Plans		Non-U.S. Plans		OPEB Plans		Total
Accumulated benefit obligation	$	1,083	$	288	$	53	$	1,424	$	921	$	269	$	56	$	1,246
Fair value of plan assets	769		254		—		1,023		697		248		—		945

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

	December 31, 2011								December 31, 2010
	U.S. Plans		Non-U.S. Plans		OPEB Plans		Total		U.S. Plans		Non-U.S. Plans		OPEB Plans		Total
Accumulated benefit obligation	$	1,083	$	288	$	53	$	1,424	$	921	$	269	$	56	$	1,246
Fair value of plan assets	769		254		—		1,023		697		248		—		945

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

	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
Equity securities:
U.S.	$	395	$	—	$	395	$	—	$	29	$	29	$	395	$	29	$	424
Non-U.S.	91		—		91		2		137		139		93		137		230
Total equity securities	486		—		486		2		166		168		488		166		654

Fixed income securities:
U.S. government	52		—		52		—		—		—		52		—		52
U.S. corporate	9		—		9		—		—		—		9		—		9
Non-U.S. government	178		—		178		—		43		43		178		43		221
Non-U.S. corporate	39		—		39		—		—		—		39		—		39
Total fixed income securities	278		—		278		—		43		43		278		43		321

Other investments:
Cash	3		38		41		—		—		—		3		38		41
Property	—		—		—		—		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

	December 31, 2010
	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
Equity securities:
U.S.	$	359	$	—	$	359	$	—	$	28	$	28	$	359	$	28	$	387
Non-U.S.	91		—		91		2		148		150		93		148		241
Total equity securities	450		—		450		2		176		178		452		176		628

Fixed income securities:
U.S. government	59		—		59		—		—		—		59		—		59
U.S. corporate	175		—		175		—		—		—		175		—		175
Non-U.S. government	—		—		—		—		34		34		—		34		34
Non-U.S. corporate	7		—		7		—		—		—		7		—		7
Total fixed income securities	241		—		241		—		34		34		241		34		275

Other investments:
Cash	4		31		35		—		—		—		4		31		35
Property	—		—		—		—		7		7		—		7		7
Investment contracts	—		—		—		—		84		84		—		84		84
Total other investments	4		31		35		—		91		91		4		122		126

Total investments	$	695	$	31	$	726	$	2	$	301	$	303	$	697	$	332	$	1,029

Net Periodic Benefit Costs Before Tax

	Year ended December 31, 2011									Year ended December 31, 2010									Year ended December 31, 2009
	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	$	43		$	21		$	64		$	42		$	20		$	62		$	44		$	18		$	62
Interest cost	58			22			80			54			20			74			50			17			67
Expected return on plan assets	(63		)	(23		)	(86		)	(58		)	(17		)	(75		)	(55		)	(16		)	(71		)
Settlements and curtailments	2			1			3			5			3			8			4			2			6
Special termination benefits	—			—			—			3			—			3			—			—			—
Actuarial losses, net	23			4			27			13			4			17			18			2			20
Prior service cost (credit), net	(1		)	—			(1		)	(1		)	—			(1		)	(1		)	1			—
Transition obligation, net	—			—			—			—			1			1			—			—			—
Net periodic benefit costs	$	62		$	25		$	87		$	58		$	31		$	89		$	60		$	24		$	84

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

	December 31, 2011												December 31, 2010
	U.S. Plans			Non-U.S. Plans			OPEB Plans			Total			U.S. Plans			Non-U.S. Plans		OPEB Plans			Total
Actuarial loss, net	$	447		$	113		$	4		$	564		$	319		$	52	$	7		$	378
Prior service cost (credit), net	(10		)	—			(2		)	(12		)	(11		)	8		(5		)	(8		)
Transition obligation, net	—			(2		)	—			(2		)	—			1		—			1
Total	$	437		$	111		$	2		$	550		$	308		$	61	$	2		$	371

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, 2012
	U.S. Plans			Non-U.S. Plans		OPEB Plans			Total
Actuarial loss, net	$	39		$	4	$	—		$	43
Prior service cost (credit), net	(1		)	—		(1		)	(2		)
Transition obligation, net	—			—		—			—
Total amount expected to be recognized	$	38		$	4	$	(1	)	$	41

Schedule of projected benefits payments

	U.S. Plans		Non-U.S. Plans		OPEB Plans		Total
Years ending December 31,
2012	$	41	$	10	$	3	$	54
2013	44		10		3		57
2014	47		10		3		60
2015	50		9		4		63
2016	54		9		4		67
2017-2021	319		62		20		401

Commitments and Contingencies (Tables)

12 Months Ended

Dec. 31, 2011

Commitments and Contingencies.

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

	Capital lease			Operating leases
Years ending December 31,
2012	$	66		$	39
2013	72			39
2014	72			27
2015	72			22
2016	73			21
Thereafter	918			91
Total future minimum rental payment	$	1,273		$	239
Less amount representing imputed interest	(597		)
Present value of future minimum rental payments under capital leases	676
Less current portion included in debt due within one year	(17		)
Long-term capital lease obligation	$	659

Schedule of aggregate carrying amount of assets held under capital lease

	December 31,
	2011			2010
Property and equipment, cost	$	742		$	740
Accumulated depreciation	(44		)	(24		)
Property and equipment, net	$	698		$	716

Schedule of purchase obligations

	Purchase obligations
Years ending December 31,
2012	$	311
2013	592
2014	408
2015	—
2016	—
Thereafter	—
Total	$	1,311

Redeemable Noncontrolling Interest (Tables)

12 Months Ended

Dec. 31, 2011

Redeemable Noncontrolling Interest

Changes in redeemable noncontrolling interest

	Years ended December 31,
	2011			2010			2009
Redeemable noncontrolling interest
Balance, beginning of period	$	25		$	—		$	—
Reclassification from noncontrolling interest	—			26			—
Net income attributable to noncontrolling interest (a)	94			13			—
Other comprehensive loss attributable to noncontrolling interest (a)	(3		)	(14		)	—
Balance, end of period	$	116		$	25		$	—

Share-Based Compensation Plans (Tables)

12 Months Ended

Dec. 31, 2011

Share Based Compensation Plans

Schedule of weighted-average assumption for option valuation

	Years ended December 31,
	2011		2010		2009
Dividend yield	4%		4%		—
Expected price volatility	40%		39%		49%
Risk-free interest rate	1.97%		2.30%		1.80%
Expected life of options	4.9 years		4.7 years		4.8 years
Weighted-average fair value of options granted	$	19.75	$	30.03	$	26.07

Summary of share settled SARs activity

	Number of awards		Weighted-average exercise price per share		Weighted-average remaining contractual term (years)	Aggregate intrinsic value (in millions)
Outstanding at January 1, 2011	189,139		$	93.28	5.76	$	—
Exercised	(1,400	)	77.73		—	—
Forfeited	(7,768	)	105.57		—	—
Outstanding at December 31, 2011	179,971		$	92.87	4.66	$	—

Vested and exercisable at December 31, 2011	179,971		$	92.87	4.66	$	—

Time-Based Awards

Share Based Compensation Plans

Summary of vested and unvested stock option activity

	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, 2011	1,653,683		$	66.37	5.29	$	5
Granted	194,342		78.76
Exercised	(210,997	)	46.37
Forfeited	(47,515	)	84.77
Expired	(10,229	)	42.79
Outstanding at December 31, 2011	1,579,284		$	70.16	2.67	$	—

Vested and exercisable at December 31, 2011	1,182,287		$	68.13	2.67	$	—

Summary of unvested share activity for time based vesting restricted shares granted under incentive plan

	Number of shares		Weighted-average grant-date fair value per share
Unvested at January 1, 2011	3,939		$	132.32
Vested	(3,939	)	132.32
Unvested at December 31, 2011	—		$	—

Summary of unvested deferred units activity

	Number of units		Weighted-average grant-date fair value per share
Unvested at January 1, 2011	1,844,784		$	75.23
Granted	1,090,747		77.55
Vested	(832,252	)	78.97
Forfeited	(163,439	)	76.94
Unvested at December 31, 2011	1,939,840		$	74.78

Performance-Based Awards

Share Based Compensation Plans

Summary of vested and unvested stock option activity

	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, 2011	179,262	$	75.30	5.22	$	—
Outstanding at December 31, 2011	179,262	$	75.30	4.23	$	—

Vested and exercisable at December 31, 2011	179,262	$	75.30	4.23	$	—

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, 2011	422,906		$	89.14
Granted	98,797		78.69
Forfeited	(105,756	)	121.89
Unvested at December 31, 2011	415,947		$	75.98

Supplemental Balance Sheet Information (Tables)

12 Months Ended

Dec. 31, 2011

Supplemental Balance Sheet Information

Schedule of other current liabilities

	December 31,
	2011		2010
Other current liabilities
Accrued payroll and employee benefits	$	340	$	270
Distribution payable	278		—
Deferred revenue	181		134
Deferred revenue of consolidated variable interest entities	16		16
Accrued taxes, other than income	127		126
Accrued interest	132		97
Unearned income	2		15
Contingent liabilities	1,229		164
Other	45		61
Total other current liabilities	$	2,350	$	883

Schedule of other long term liabilities

	December 31,
	2011		2010
Other long-term liabilities
Long-term income taxes payable	$	729	$	675
Accrued pension liabilities	579		426
Deferred revenue	244		302
Deferred revenue of consolidated variable interest entities	85		91
Drilling contract intangibles	103		152
Accrued retiree life insurance and medical benefits	49		52
Other	114		93
Total other long-term liabilities	$	1,903	$	1,791

Supplemental Cash Flow Information (Tables)

12 Months Ended

Dec. 31, 2011

Supplemental Cash Flow Information

Schedule of changes in operating assets and liabilities

	Years ended December 31,
	2011			2010			2009
Changes in operating assets and liabilities
Decrease (increase) in accounts receivable	$	(174	)	$	386		$	504
Increase in other current assets	(73		)	(75		)	(50		)
Increase in other assets	(5		)	(40		)	(30		)
Increase (decrease) in accounts payable and other current liabilities	978			227			(60		)
Decrease in other long-term liabilities	(34		)	(52		)	(7		)
Change in income taxes receivable / payable, net	53			(37		)	77
	$	745		$	409		$	434

Additional cash flow information

	Years ended December 31,
	2011		2010		2009
Certain cash operating activities
Cash payments for interest	$	626	$	641	$	683
Cash payments for income taxes	338		493		663

Non-cash investing and financing activities
Capital expenditures, accrued at end of period (a)	$	68	$	69	$	139
Asset capitalized under capital leases (b)	—		—		716
Non-cash proceeds received for the sale of assets (c)	—		134		—

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

Fair Value of Financial Instruments (Tables)

12 Months Ended

Dec. 31, 2011

Fair Value of Financial Instruments

Carrying amounts and fair values of the financial instruments

	December 31, 2011				December 31, 2010
	Carrying amount		Fair value		Carrying amount		Fair value
Cash and cash equivalents	$	4,017	$	4,017	$	3,394	$	3,394
Accounts receivable	2,049		2,049		1,653		1,653
Notes receivable and working capital loan receivable	139		139		115		115
Restricted cash investments	928		975		47		47
Long-term debt, including current maturities	12,698		13,074		10,271		10,562
Long-term debt of consolidated variable interest entities, including current maturities	838		838		950		964
Derivative instruments, assets	36		36		21		21
Derivative instruments, liabilities	38		38		13		13

- Definition

This item represents certain of the disclosures concerning 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+ Details

Variable Interest Entities (Tables)

12 Months Ended

Dec. 31, 2011

Variable Interest Entities

Carrying Amounts of Variable Interest Entities

	December 31, 2011						December 31, 2010
	Assets		Liabilities		Net carrying amount		Assets		Liabilities		Net carrying amount
Variable interest entity
TPDI	$	1,562	$	673	$	889	$	1,598	$	763	$	835
ADDCL	930		334		596		864		345		519
Total	$	2,492	$	1,007	$	1,485	$	2,462	$	1,108	$	1,354

Operating Segments, Geographic Analysis and Major Customers (Tables)

12 Months Ended

Dec. 31, 2011

Operating Segments, Geographic Analysis and Major Customers

Schedule of operating revenues by country

	Years ended December 31,
	2011		2010		2009
Operating revenues
U.S.	$	1,975	$	2,087	$	2,209
U.K.	1,211		1,183		1,563
Brazil	1,019		1,288		1,108
Other countries (a)	4,937		4,908		6,561
Total operating revenues	$	9,142	$	9,466	$	11,441

(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

	December 31,
	2011		2010
Long-lived assets
U.S.	$	6,549	$	5,519
Brazil	2,185		2,472
India	1,593		2,632
Other countries (a)	12,202		10,696
Total long-lived assets	$	22,529	$	21,319

(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.

Condensed Consolidating Financial Information (Tables)

12 Months Ended

Dec. 31, 2011

Condensed Consolidating Financial Information

Schedule of condensed consolidating statement of operations

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

Operating revenues	$	—		$	—		$	9,160		$	(18	)	$	9,142
Cost and expenses	44			4			8,663			(18		)	8,693
Loss on impairment	—			—			(5,229		)	—			(5,229		)
Gain on disposal of assets, net	—			—			4			—			4
Operating loss	(44		)	(4		)	(4,728		)	—			(4,776		)

Other income (expense), net
Interest expense, net	(11		)	(510		)	(56		)	—			(577		)
Equity in earnings	(5,670		)	(5,145		)	18			10,815			18
Other, net	—			9			(108		)	—			(99		)
	(5,681		)	(5,646		)	(146		)	10,815			(658		)
Loss from continuing operations before income tax expense	(5,725		)	(5,650		)	(4,874		)	10,815			(5,434		)
Income tax expense	—			—			395			—			395
Loss from continuing operations	(5,725		)	(5,650		)	(5,269		)	10,815			(5,829		)
Income from discontinued operations, net of tax	—			—			197			—			197

Net loss	(5,725		)	(5,650		)	(5,072		)	10,815			(5,632		)
Net income attributable to noncontrolling interest	—			—			93			—			93
Net loss attributable to controlling interest	$	(5,725	)	$	(5,650	)	$	(5,165	)	$	10,815		$	(5,725	)

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

Operating revenues	$	—		$	—		$	9,481		$	(15	)	$	9,466
Cost and expenses	45			3			6,823			(15		)	6,856
Loss on impairment	—			—			(1,010		)	—			(1,010		)
Gain on disposal of assets, net	—			—			257			—			257
Operating income (loss)	(45		)	(3		)	1,905			—			1,857

Other income (expense), net
Interest income (expense), net	1			(494		)	(51		)	—			(544		)
Equity in earnings	1,005			1,519			8			(2,524		)	8
Other, net	—			(7		)	(24		)	—			(31		)
	1,006			1,018			(67		)	(2,524		)	(567		)
Income from continuing operations before income tax expense	961			1,015			1,838			(2,524		)	1,290
Income tax expense	—			—			336			—			336
Income from continuing operations	961			1,015			1,502			(2,524		)	954
Income from discontinued operations, net of tax	—			—			34			—			34

Net income	961			1,015			1,536			(2,524		)	988
Net income attributable to noncontrolling interest	—			—			27			—			27

Net income attributable to controlling interest	$	961		$	1,015		$	1,509		$	(2,524	)	$	961

	Year ended December 31, 2009
	Parent Guarantor			Subsidiary Issuer			Other Subsidiaries			Consolidating adjustments			Consolidated

Operating revenues	$	—		$	—		$	11,455		$	(14	)	$	11,441
Cost and expenses	26			4			6,692			(14		)	6,708
Loss on impairment	—			—			(334		)	—			(334		)
Loss on disposal of assets, net	—			—			(9		)	—			(9		)
Operating income (loss)	(26		)	(4		)	4,420			—			4,390

Other income (expense), net
Interest income (expense), net	1			(521		)	41			—			(479		)
Equity in earnings	3,206			3,773			6			(6,979		)	6
Other, net	—			(43		)	45			—			2
	3,207			3,209			92			(6,979		)	(471		)
Income from continuing operations before income tax expense	3,181			3,205			4,512			(6,979		)	3,919
Income tax expense	—			—			723			—			723
Income from continuing operations	3,181			3,205			3,789			(6,979		)	3,196
Loss from discontinued operations, net of tax	—			—			(26		)	—			(26		)

Net income	3,181			3,205			3,763			(6,979		)	3,170
Net loss attributable to noncontrolling interest	—			—			(11		)	—			(11		)

Net income attributable to controlling interest	$	3,181		$	3,205		$	3,774		$	(6,979	)	$	3,181

Schedule of condensed consolidating balance sheet

	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		4,493		(1,693		)	3,592
Total current assets	11		3,577		5,714		(1,693		)	7,609

Property and equipment, net	1		—		22,528		—			22,529
Goodwill	—		—		3,205		—			3,205
Investment in affiliates	16,503		27,582		—		(44,085		)	—
Other assets	—		1,368		17,908		(17,531		)	1,745
Total assets	16,515		32,527		49,355		(63,309		)	35,088

Liabilities and equity
Debt due within one year	—		1,693		346		—			2,039
Other current liabilities	294		367		4,351		(1,693		)	3,319
Total current liabilities	294		2,060		4,697		(1,693		)	5,358

Long-term debt	495		14,308		14,225		(17,531		)	11,497
Other long-term liabilities	25		439		1,962		—			2,426
Total long-term liabilities	520		14,747		16,187		(17,531		)	13,923

Commitments and contingencies
Redeemable noncontrolling interest	—		—		116		—			116

Total equity	15,701		15,720		28,355		(44,085		)	15,691
Total liabilities and equity	$	16,515	$	32,527	$	49,355	$	(63,309	)	$	35,088

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

Assets
Cash and cash equivalents	$	38	$	2,041	$	1,315	$	—		$	3,394
Other current assets	12		788		3,189		(1,188		)	2,801
Total current assets	50		2,829		4,504		(1,188		)	6,195

Property and equipment, net	1		—		21,318		—			21,319
Goodwill	—		—		8,132		—			8,132
Investment in affiliates	21,373		33,473		19		(54,846		)	19
Other assets	—		1,017		14,001		(13,872		)	1,146
Total assets	21,424		37,319		47,974		(69,906		)	36,811

Liabilities and equity
Debt due within one year	—		1,891		121		—			2,012
Other current liabilities	21		444		2,547		(1,188		)	1,824
Total current liabilities	21		2,335		2,668		(1,188		)	3,836

Long-term debt	—		13,354		9,727		(13,872		)	9,209
Other long-term liabilities	20		292		2,054		—			2,366
Total long-term liabilities	20		13,646		11,781		(13,872		)	11,575

Commitments and contingencies
Redeemable noncontrolling interest	—		—		25		—			25

Total equity	21,383		21,338		33,500		(54,846		)	21,375
Total liabilities and equity	$	21,424	$	37,319	$	47,974	$	(69,906	)	$	36,811

Schedule of condensed consolidating statement of cash flows

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

Cash flows from operating activities	$	(52	)	$	503		$	1,334		$	—		$	1,785

Cash flows from investing activities
Capital expenditures	—			—			(1,020		)	—			(1,020		)
Investment in business combination, net of cash acquired	—			—			(1,246		)	—			(1,246		)
Proceeds from disposal of assets, net	—			—			177			—			177
Proceeds from disposal of discontinued operations, net	—			—			284			—			284
Investing activities with affiliates, net	(875		)	(325		)	(693		)	1,893			—
Other, net	—			(23		)	(68		)	—			(91		)
Net cash provided by (used in) investing activities	(875		)	(348		)	(2,566		)	1,893			(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 share issuance, net	1,211			—			—			—			1,211
Distribution of qualifying additional paid-in capital	(763		)	—			—			—			(763		)
Financing activities with affiliates, net	495			43			1,355			(1,893		)	—
Other, net	(57		)	(35		)	(64		)	—			(156		)
Net cash provided by (used in) financing activities	892			597			1,138			(1,893		)	734

Net increase (decrease) in cash and cash equivalents	(35		)	752			(94		)	—			623
Cash and cash equivalents at beginning of period	38			2,041			1,315			—			3,394
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	)	$	4,337		$	—		$	3,946

Cash flows from investing activities
Capital expenditures	(4		)	—			(1,387		)	—			(1,391		)
Proceeds from insurance recoveries for loss of drilling unit	—			—			560			—			560
Proceeds from disposal of assets, net	—			—			60			—			60
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			307			—			2,264
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		$	1,315		$	—		$	3,394

	Year ended December 31, 2009
	Parent Guarantor			Subsidiary Issuer			Other Subsidiaries			Consolidating adjustments			Consolidated

Cash flows from operating activities	$	(24	)	$	(429	)	$	6,051		$	—		$	5,598

Cash flows from investing activities
Capital expenditures	(1		)	—			(3,040		)	—			(3,041		)
Investing activities with affiliates, net	29			1,667			(2,068		)	372			—
Other, net	—			—			347			—			347
Net cash provided by (used in) investing activities	28			1,667			(4,761		)	372			(2,694		)

Cash flows from financing activities
Changes in short-term borrowings, net	—			(382		)	—			—			(382		)
Proceeds from debt	—			—			514			—			514
Repayments of debt	—			(2,865		)	(6		)	—			(2,871		)
Financing activities with affiliates, net	—			2,008			(1,636		)	(372		)	—
Other, net	1			4			(3		)	—			2
Net cash provided by (used in) financing activities	1			(1,235		)	(1,131		)	(372		)	(2,737		)

Net increase in cash and cash equivalents	5			3			159			—			167
Cash and cash equivalents at beginning of period	—			114			849			—			963
Cash and cash equivalents at end of period	$	5		$	117		$	1,008		$	—		$	1,130

Quarterly Results (Unaudited) (Tables)

12 Months Ended

Dec. 31, 2011

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)
2011
Operating revenues	$	2,144	$	2,334	$	2,242		$	2,422
Operating income (loss) (a)	372		391		268			(5,807		)
Income (loss) from continuing operations	164		162		(53		)	(6,102		)
Net income (loss) attributable to controlling interest (a) (b)	310		155		(71		)	(6,119		)
Per share earnings (loss) from continuing operations
Basic	$	0.42	$	0.47	$	(0.20	)	$	(18.70	)
Diluted	$	0.42	$	0.47	$	(0.20	)	$	(18.70	)
Weighted-average shares outstanding
Basic	319		320		320			329
Diluted	320		320		320			329

2010
Operating revenues	$	2,579	$	2,479	$	2,281		$	2,127
Operating income (loss) (c)	942		949		634			(668		)
Income (loss) from continuing operations	683		712		363			(804		)
Net income (loss) attributable to controlling interest (c)	677		715		368			(799		)
Per share earnings (loss) from continuing operations
Basic	$	2.09	$	2.20	$	1.10		$	(2.53	)
Diluted	$	2.08	$	2.20	$	1.10		$	(2.53	)
Weighted-average shares outstanding
Basic	321		319		319			319
Diluted	322		320		319			319

(b) First, third and fourth quarters included gains (losses) on disposal of discontinued operations in the amount of $173 million, $(4) million and $12 million, respectively.

Nature of Business (Details)	Dec. 31, 2011 drillingunit	Oct. 31, 2011 drillingunit
Nature of Business
Number of mobile offshore drilling units	135
Number of High-Specification Floaters (in drilling units)	50
Number of Midwater Floaters (in drilling units)	25
Number of High-Specification Jackups (in drilling units)	9
Number of Standard Jackups (in drilling units)	50
Number of swamp barges (in drilling units)	1
Number of Ultra-Deepwater Floaters under construction (in drilling units)	2	2
Number of High-Specification Jackups under construction (in drilling units)	4

Significant Accounting Policies (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 Y D M	Dec. 31, 2010	Dec. 31, 2009
Significant Accounting Policies
Equity in earnings of unconsolidated affiliates	$ 18	$ 8	$ 6
Carrying amounts of investments in and advances to unconsolidated affiliates	1	19
Business combination
Period from date of acquisition for completion of assessments of fair values of acquired assets and liabilities (in years)	1
Contract drilling intangible revenues
Contract drilling intangible revenues	45	98	281
Share-based compensation expense
Number of trading days considered for calculation of average stock price	30
Share-based compensation expense	95	102	81
Income tax benefit on share-based compensation expense	16	13	11
Capitalized interest
Capitalized interest costs on construction work in progress	39	89	182
Foreign currency
Net foreign currency exchange loss	(99)	1	(33)
Cash and cash equivalents
Maximum period within which restriction is expected to expire for classifying restricted cash and investment as current assets (in years)	1
Minimum period after which restriction is expected to expire for classifying restricted cash and investment as other assets (in years)	1
Maximum term of original maturity to classify instruments as cash and cash equivalents (in months)	3
Restricted cash investments	928	47
Restricted cash investments classified in other current assets	182
Restricted cash investments classified in other assets	746
Allowance for doubtful accounts
Allowance for doubtful accounts	28	38
Materials and supplies
Allowance for obsolescence on materials and supplies	73	70
Assets held for sale
Assets held for sale, maximum		1
Assets held for sale, included in current assets	26
Property and equipment
Property and equipment as a percentage of total assets (as a percent)	64.00%
Depreciation and Amortization	(1,449)	(1,536)	(1,433)
Earnings (loss) from continuing operations (in dollars per share)	$ (18.40)	$ 2.88	$ 9.92
Drilling rig units
Property and equipment
Number of rigs for which useful life was adjusted	2	5	10
Drilling rig units \| Service life
Property and equipment
Depreciation and Amortization	$ 2	$ 23	$ 23
Earnings (loss) from continuing operations (in dollars per share)	$ (0.01)	$ (0.07)	$ (0.07)
Drilling rig units \| Maximum
Property and equipment
Estimated original useful life (in years)	35
Estimated useful life before adjustment (in years)	30	36	35
Estimated useful life after adjustment (in years)	38	39	50
Drilling rig units \| Minimum
Property and equipment
Estimated original useful life (in years)	18
Estimated useful life before adjustment (in years)	20	20	30
Estimated useful life after adjustment (in years)	23	25	33
Buildings and improvements \| Maximum
Property and equipment
Estimated original useful life (in years)	30
Buildings and improvements \| Minimum
Property and equipment
Estimated original useful life (in years)	10
Machinery and equipment \| Maximum
Property and equipment
Estimated original useful life (in years)	12
Machinery and equipment \| Minimum
Property and equipment
Estimated original useful life (in years)	4

Significant Accounting Policies (Details 2) (USD $)	3 Months Ended		12 Months Ended
Significant Accounting Policies (Details 2) (USD $)	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 unit Y Assumption AssetGroup	Dec. 31, 2010	Dec. 31, 2009
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			$ 28,000,000
Loss on impairment of assets		1,000,000,000	5,229,000,000	1,010,000,000	334,000,000
Loss on impairment of assets held for sale			28,000,000
Goodwill and other indefinite-lived intangible assets
Number of reporting units			2
Estimated loss on impairment of goodwill	5,200,000,000		5,200,000,000
Estimated loss on impairment of goodwill per diluted share			$ 16.15
Impairment loss on trade name intangible asset					6,000,000
Pension and other postretirement benefits
Recognition period of investment gains or losses related to asset valuation for determining net periodic benefit cost (in years)			5
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	640,000,000	469,000,000	640,000,000	469,000,000
Net periodic benefit costs			88,000,000	91,000,000	87,000,000
Customer relationships
Long-lived assets and definite-lived intangible assets
Loss on impairment of assets per diluted share					$ 0.15
Impairment					49,000,000
ADTI trade name
Long-lived assets and definite-lived intangible assets
Loss on impairment of assets per diluted share					$ 0.02
Goodwill and other indefinite-lived intangible assets
Impairment loss on trade name intangible asset					6,000,000
GSF Arctic II and GSF Arctic IV
Long-lived assets and definite-lived intangible assets
Loss on impairment of assets held for sale					279,000,000
Loss on impairment of assets per diluted share					$ 0.87
Standard Jackup asset group
Long-lived assets and definite-lived intangible assets
Impairment loss of long-lived assets				$ 1,000,000,000
Loss on impairment of assets per diluted share				$ 3.15

Business Combination (Details) (Aker Drilling)	1 Months Ended		3 Months Ended	12 Months Ended
Business Combination (Details) (Aker Drilling)	Oct. 31, 2011 USD ($)	Aug. 31, 2011	Dec. 31, 2011 USD ($)	Dec. 31, 2011 USD ($) M	Dec. 31, 2010 USD ($)	Oct. 03, 2011 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 (in NOK per share)		26.5
Percentage of equity held by entity immediately before the acquisition date						0.99	0.99
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						756,000,000
Current liabilities						272,000,000
Long-term debt						1,600,000,000
Restricted cash investment	901,000,000
Goodwill						273,000,000
Number of months of acquiree's operating results included in financial statements				3
Contract drilling revenues associated with the operations of Aker Drilling included in operating revenues				100,000,000
Pro forma combined operating results
Operating revenues			100,000,000	9,454,000,000	9,797,000,000
Operating income (loss)				(4,628,000,000)	1,975,000,000
Income (loss) from continuing operations				$ (5,806,000,000)	$ 999,000,000
Per share earnings (loss) from continuing operations
Basic (in dollars per share)				$ (18.33)	$ 3.02
Diluted (in dollars per share)				$ (18.33)	$ 3.02

Impairments (Details) (USD $)	3 Months Ended	12 Months Ended			12 Months Ended						12 Months Ended			12 Months Ended
Impairments (Details) (USD $)	Dec. 31, 2011	Dec. 31, 2011	Dec. 31, 2009	Dec. 31, 2010	Dec. 31, 2009 GSF Arctic II and GSF Arctic IV	Dec. 31, 2011 GSF Britannia, George H. Galloway, GSF Labrador and Searex IV	Dec. 31, 2011 GSF Britannia, George H. Galloway, GSF Labrador and Searex IV Maximum	Dec. 31, 2009 Trade name intangible asset	Dec. 31, 2011 Trade name intangible asset	Dec. 31, 2010 Trade name intangible asset	Dec. 31, 2009 Customer relationships	Dec. 31, 2011 Customer relationships	Dec. 31, 2010 Customer relationships	Dec. 31, 2010 Standard Jackup asset group
Assets held for sale
Loss on impairment of assets held for sale		$ 28,000,000			$ 279,000,000	$ 28,000,000
Aggregate losses on asset held for sale tax effect							1,000,000
Loss on impairment of assets per diluted share					$ 0.87	$ 0.09		$ 0.02			$ 0.15			$ 3.15
Impairment loss of long-lived assets														1,000,000,000
Impairment of goodwill and other indefinite-lived intangible assets
Impairment loss on indefinite-lived intangible asset			6,000,000					6,000,000
Estimated loss on impairment of goodwill	5,200,000,000	5,200,000,000
Estimate of loss on impairment of goodwill per diluted share		$ 16.15
Carrying amount of indefinite-lived intangible assets									39,000,000	39,000,000
Impairment of definite-lived intangible assets
Impairment loss on finite-lived intangible asset											49,000,000
Carrying amount of finite-lived intangible assets	$ 54,000,000	$ 54,000,000	$ 88,000,000	$ 65,000,000								$ 54,000,000	$ 59,000,000

Income Taxes (Details) (USD $)	12 Months Ended
Income Taxes (Details) (USD $)	Dec. 31, 2011 employee jurisdiction subsidiary Y issue	Dec. 31, 2010	Dec. 31, 2009
Components of provision (benefit) for income taxes
Current tax expense	$ 426,000,000	$ 450,000,000	$ 738,000,000
Deferred tax expense (benefit)	(31,000,000)	(114,000,000)	(15,000,000)
Income tax expense	395,000,000	336,000,000	723,000,000
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	(425,000,000)	101,000,000	307,000,000
Taxes on earnings subject to rates greater than the Swiss federal statutory rate	285,000,000	107,000,000	288,000,000
Taxes on impairment loss subject to rates less than the Swiss federal statutory rate	409,000,000	79,000,000
Taxes on asset sales subject to rates less than the Swiss federal statutory rate	(16,000,000)
Taxes on litigation matters subject to rates less than the Swiss federal statutory rate	78,000,000
Changes in unrecognized tax benefits, net	62,000,000	71,000,000	135,000,000
Change in valuation allowance	19,000,000	4,000,000	49,000,000
Benefit from foreign tax credits	(28,000,000)	(23,000,000)	(49,000,000)
Taxes on asset acquisition costs at rates lower than the Swiss federal statutory rate	8,000,000
Other, net	3,000,000	(3,000,000)	(7,000,000)
Income tax expense	395,000,000	336,000,000	723,000,000
Deferred tax assets
Drilling contract intangibles	2,000,000	6,000,000
Net operating loss carryforwards	341,000,000	184,000,000
Tax credit carryforwards	45,000,000	29,000,000
Accrued payroll expenses not currently deductible	77,000,000	72,000,000
Deferred income	67,000,000	84,000,000
Valuation allowance	(183,000,000)	(164,000,000)
Other	81,000,000	61,000,000
Total deferred tax assets	430,000,000	272,000,000
Deferred tax liabilities
Depreciation and amortization	(749,000,000)	(680,000,000)
Drilling management services intangibles	(25,000,000)	(26,000,000)
Other	(37,000,000)	(26,000,000)
Total deferred tax liabilities	(811,000,000)	(732,000,000)
Net deferred tax liabilities	(381,000,000)	(460,000,000)
U.S. foreign tax credit carryforwards	45,000,000
Tax effect of Brazilian NOLs	57,000,000	62,000,000
Norwegian NOLs acquired in connection with Aker Drilling acquisition		141,000,000
Deferred taxes
Valuation allowance for non-current deferred tax assets	183,000,000	164,000,000
Indefinitely reinvested earnings of subsidiaries	2,200,000,000
Estimated taxes on unremitted earnings of subsidiaries, low end of range	150,000,000
Estimated taxes on unremitted earnings of subsidiaries, high end of range	200,000,000
Reconciliation of unrecognized tax benefits, excluding interest and penalties
Balance, beginning of period	485,000,000	460,000,000	372,000,000
Additions for current year tax positions	45,000,000	46,000,000	64,000,000
Additions for prior year tax positions	23,000,000	9,000,000	62,000,000
Reductions for prior year tax positions		(11,000,000)	(22,000,000)
Settlements	(42,000,000)	(17,000,000)	(3,000,000)
Reductions related to statute of limitation expirations	(2,000,000)	(2,000,000)	(13,000,000)
Balance, end of period	509,000,000	485,000,000	460,000,000
Unrecognized tax benefits
Unrecognized tax benefits, excluding interest and penalties	509,000,000	485,000,000	460,000,000
Interest and penalties	272,000,000	235,000,000
Unrecognized tax benefits, including interest and penalties	781,000,000	720,000,000
Unrecognized tax benefits that would favorably impact effective tax rate	781,000,000
Interest and penalties related to unrecognized tax benefits recognized as a component of income tax expense	37,000,000	35,000,000	51,000,000
Tax returns
Minimum range tax returns are subject to examination (in years)	3
Maximum range tax returns are subject to examination (in years)	6
Number of jurisdictions with extensions beyond statute of limitations	2
Maximum number of years agreed to extensions beyond the statute of limitations	17
2005 transfer pricing adjustment, exclusive of interest	50,000,000
Number of tax issues relating to assessment	2
2006 and 2007 income tax adjustments, excluding interest	278,000,000
2006 through 2009 restructuring transactions tax adjustments	295,000,000
2006 through 2009 withholding and other tax adjustments	160,000,000
Assessed penalties associated with the various adjustments for 2006 and 2007 audits	88,000,000
Norway tax assessment due to restructuring transactions	262,000,000
Norway tax assessment due to migration of subsidiary	115,000,000
Norway tax assessment due to 2001 dividend payment	69,000,000
Norway tax assessment due to foreign exchange deductions and dividend withholding taxes	7,000,000
Guarantee amount for tax assessment related to the migration of subsidiary	120,000,000
Norway tax additional financial security	776,000,000
Percentage of penalties to be assessed by Norway tax authorities	60.00%
Brazil tax assessment for income tax returns 2000 to 2004	109,000,000
Percentage of penalties to be assessed by Brazil tax authorities	75.00%
Brazil tax assessment penalty	82,000,000
Brazil tax assessment interest	$ 150,000,000
Number of employees of former external advisors indicted	2
Number of subsidiaries against which notification of criminal charges are issued	2

Discontinued Operations (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended			12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Mar. 31, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Discontinued Operations
Gain on the disposal of the discontinued operations before tax	$ 12	$ (4)	$ 173	$ 181
Proceeds from disposal of discontinued operations, net				284
Summarized results of discontinued operations
Operating revenues				62	110	115
Costs and expenses				(55)	(99)	(110)
Loss on impairment				(10)	(2)
Income (loss) from discontinued operations before income tax expense				178	9	5
Income tax benefit (expense)				19	25	(31)
Income from discontinued operations, net of tax				197	34	(26)
Impairment loss per diluted share from discontinued operations				$ 0.03	$ 0.01
Assets
Oil and gas properties, net	24			24
Other related assets	2			2
Assets held for sale	26			26
Accounts receivable	6			6	22
Other assets	25			25	17
Other current assets	31			31	39
Rig and related equipment, net					86
Oil and gas properties, net					53
Other assets					139
Liabilities
Accounts payable	3			3	15
Other liabilities	14			14	13
Other current liabilities	17			17	28
Asset retirement obligation					9
Deferred taxes					19
Other long-term liabilities					28
Challenger Minerals
Discontinued Operations
Gain on the disposal of the discontinued operations before tax				12
Proceeds from disposal of discontinued operations, net	24
Caspian Sea Operations
Discontinued Operations
Proceeds from disposal of discontinued operations, net				259
Gain on disposal of the discontinued operations per diluted share				$ 0.52
Summarized results of discontinued operations
Gain on disposal of discontinued operations, net of tax				$ 169

Earnings (Loss) Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Numerator for earnings per share, basic
Income (loss) from continuing operations attributable to controlling interest									$ (5,922)	$ 927	$ 3,207
Undistributed earnings allocable to participating securities										(5)	(18)
Income (loss) from continuing operations available to shareholders									(5,922)	922	3,189
Denominator for earnings per share, basic
Weighted-average shares outstanding	329	320	320	319	319	319	319	321	322	320	320
Weighted-average shares for per share calculation, basic	329	320	320	319	319	319	319	321	322	320	320
Per share earnings (loss) from continuing operations, basic									$ (18.40)	$ 2.88	$ 9.95
Numerator for earnings per share, diluted
Income (loss) from continuing operations attributable to controlling interest									(5,922)	927	3,207
Undistributed earnings allocable to participating securities										(5)	(18)
Income from continuing operations available to shareholders									$ (5,922)	$ 922	$ 3,189
Denominator for earnings per share, diluted
Weighted-average shares outstanding	329	320	320	319	319	319	319	321	322	320	320
Effect of dilutive securities:
Stock options and other share based awards (in shares)											1
Weighted-average shares for per share calculation, diluted	329	320	320	320	319	319	320	322	322	320	321
Per share earnings (loss) from continuing operations, diluted									$ (18.40)	$ 2.88	$ 9.92
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%
Stock-based awards
Anti-dilutive securities
Share-based awards excluded from earnings per share calculation									2.4	2.2	1.7

Other Comprehensive Income (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Allocation of other comprehensive income (loss)
Unrecognized components of net periodic benefit costs	$ (204)	$ (8)	$ 37
Unrecognized gain (loss) on derivative instruments	(13)	(29)	(2)
Unrecognized loss on marketable securities	(13)
Recognized components of net periodic benefit costs	25	16	24
Recognized (gain) loss on derivative instruments	11	12	6
Recognized loss on marketable security	13		1
Other comprehensive income (loss) before income taxes	(181)	(9)	66
Income taxes related to other comprehensive income (loss)	13	(9)	24
Other comprehensive income (loss), net of income taxes	(168)	(18)	90
Components of accumulated comprehensive income (loss), net of tax
Accumulated other comprehensive income (loss)	(496)	(332)
Tax effect of changes in accumulated other comprehensive income	49	36
Controlling interest
Allocation of other comprehensive income (loss)
Unrecognized components of net periodic benefit costs	(204)	(8)	37
Unrecognized gain (loss) on derivative instruments	3	(10)	(4)
Unrecognized loss on marketable securities	(13)
Recognized components of net periodic benefit costs	25	16	24
Recognized (gain) loss on derivative instruments	(1)	14	3
Recognized loss on marketable security	13		1
Other comprehensive income (loss) before income taxes	(177)	12	61
Income taxes related to other comprehensive income (loss)	13	(9)	24
Other comprehensive income (loss), net of income taxes	(164)	3	85
Components of accumulated comprehensive income (loss), net of tax
Unrecognized components of net periodic benefit costs	(501)	(335)
Unrecognized gain (loss) on derivative investments	7	5
Unrecognized loss on marketable securities	(2)	(2)
Accumulated other comprehensive income (loss)	(496)	(332)
Non-controlling interest and Redeemable non-controlling interest
Allocation of other comprehensive income (loss)
Unrecognized gain (loss) on derivative instruments	(16)	(19)	2
Recognized (gain) loss on derivative instruments	12	(2)	3
Other comprehensive income (loss) before income taxes	(4)	(21)	5
Other comprehensive income (loss), net of income taxes	(4)	(21)	5
Non-controlling interest
Components of accumulated comprehensive income (loss), net of tax
Unrecognized gain (loss) on derivative investments	(3)	(3)
Accumulated other comprehensive income (loss)	(3)	(3)
Redeemable non-controlling interest
Components of accumulated comprehensive income (loss), net of tax
Unrecognized gain (loss) on derivative investments	(17)	(13)
Accumulated other comprehensive income (loss)	$ (17)	$ (13)

Drilling Fleet (Details) (USD $)	1 Months Ended	12 Months Ended			36 Months Ended	72 Months Ended	12 Months Ended	72 Months Ended		12 Months Ended	72 Months Ended		12 Months Ended		72 Months Ended		12 Months Ended		72 Months Ended	12 Months Ended		72 Months Ended	12 Months Ended	72 Months Ended	12 Months Ended			36 Months Ended	72 Months Ended		12 Months Ended			36 Months Ended	72 Months Ended	12 Months Ended			36 Months Ended	72 Months Ended	12 Months Ended		36 Months Ended	72 Months Ended	12 Months Ended		36 Months Ended	72 Months Ended		12 Months Ended		36 Months Ended	72 Months Ended	12 Months Ended		36 Months Ended	72 Months Ended	12 Months Ended		36 Months Ended	72 Months Ended	12 Months Ended		72 Months Ended	12 Months Ended	36 Months Ended	72 Months Ended	12 Months Ended	36 Months Ended	72 Months Ended	12 Months Ended			36 Months Ended	72 Months Ended	12 Months Ended			72 Months Ended
Drilling Fleet (Details) (USD $)	Mar. 31, 2010	Dec. 31, 2011 drillingunit	Dec. 31, 2010 drillingunit	Dec. 31, 2009	Dec. 31, 2008	Dec. 31, 2011	Dec. 31, 2011 Ultra-Deepwater Floater TBN1	Dec. 31, 2011 Ultra-Deepwater Floater TBN1	Oct. 31, 2011 Ultra-Deepwater Floater TBN1	Dec. 31, 2011 Ultra-Deepwater Floater TBN2	Dec. 31, 2011 Ultra-Deepwater Floater TBN2	Oct. 31, 2011 Ultra-Deepwater Floater TBN2	Dec. 31, 2011 Transocean Honor	Dec. 31, 2010 Transocean Honor	Dec. 31, 2011 Transocean Honor	Nov. 30, 2010 Transocean Honor design	Dec. 31, 2011 Transocean Siam Driller	Dec. 31, 2010 Transocean Siam Driller	Dec. 31, 2011 Transocean Siam Driller	Dec. 31, 2011 Transocean Andaman	Dec. 31, 2010 Transocean Andaman	Dec. 31, 2011 Transocean Andaman	Dec. 31, 2011 Transocean Ao Thai	Dec. 31, 2011 Transocean Ao Thai	Dec. 31, 2011 Deepwater Champion	Dec. 31, 2010 Deepwater Champion	Dec. 31, 2009 Deepwater Champion	Dec. 31, 2008 Deepwater Champion	Dec. 31, 2011 Deepwater Champion	Nov. 30, 2007 Deepwater Champion	Dec. 31, 2011 Discoverer Luanda	Dec. 31, 2010 Discoverer Luanda	Dec. 31, 2009 Discoverer Luanda	Dec. 31, 2008 Discoverer Luanda	Dec. 31, 2011 Discoverer Luanda	Dec. 31, 2011 Discoverer India	Dec. 31, 2010 Discoverer India	Dec. 31, 2009 Discoverer India	Dec. 31, 2008 Discoverer India	Dec. 31, 2011 Discoverer India	Dec. 31, 2010 Dhirubhai Deepwater KG2	Dec. 31, 2009 Dhirubhai Deepwater KG2	Dec. 31, 2008 Dhirubhai Deepwater KG2	Dec. 31, 2011 Dhirubhai Deepwater KG2	Dec. 31, 2010 Development Driller III	Dec. 31, 2009 Development Driller III	Dec. 31, 2008 Development Driller III	Dec. 31, 2011 Development Driller III	Nov. 30, 2007 Development Driller III	Dec. 31, 2010 Discoverer Inspiration	Dec. 31, 2009 Discoverer Inspiration	Dec. 31, 2008 Discoverer Inspiration	Dec. 31, 2011 Discoverer Inspiration	Dec. 31, 2010 Discoverer Americas	Dec. 31, 2009 Discoverer Americas	Dec. 31, 2008 Discoverer Americas	Dec. 31, 2011 Discoverer Americas	Dec. 31, 2010 Discoverer Clear Leader	Dec. 31, 2009 Discoverer Clear Leader	Dec. 31, 2008 Discoverer Clear Leader	Dec. 31, 2011 Discoverer Clear Leader	Dec. 31, 2010 Petrobras 10000	Dec. 31, 2009 Petrobras 10000 Y	Dec. 31, 2011 Petrobras 10000	Dec. 31, 2009 Dhirubhai Deepwater KG1	Dec. 31, 2008 Dhirubhai Deepwater KG1	Dec. 31, 2011 Dhirubhai Deepwater KG1	Dec. 31, 2009 Sedco 700-series upgrades	Dec. 31, 2008 Sedco 700-series upgrades	Dec. 31, 2011 Sedco 700-series upgrades	Dec. 31, 2011 Capitalized interest	Dec. 31, 2010 Capitalized interest	Dec. 31, 2009 Capitalized interest	Dec. 31, 2008 Capitalized interest	Dec. 31, 2011 Capitalized interest	Dec. 31, 2011 Mobilization costs	Dec. 31, 2010 Mobilization costs	Dec. 31, 2009 Mobilization costs	Dec. 31, 2011 Mobilization costs
Drilling Fleet
Construction work in progress, recorded in property and equipment		$ 1,400,000,000	$ 1,500,000,000			$ 1,400,000,000
Capital expenditures and other capital additions, including capitalized interest, for our major construction projects
Capital expenditures and other capital additions, including capitalized interest costs		813,000,000	966,000,000	3,187,000,000	4,163,000,000	9,129,000,000	138,000,000	138,000,000		137,000,000	137,000,000		119,000,000	97,000,000	216,000,000		110,000,000	9,000,000	119,000,000	110,000,000	9,000,000	119,000,000	79,000,000	79,000,000	43,000,000	206,000,000	263,000,000	264,000,000	776,000,000		12,000,000	174,000,000	220,000,000	315,000,000	721,000,000	6,000,000	203,000,000	291,000,000	250,000,000	750,000,000	36,000,000	371,000,000	270,000,000	677,000,000	24,000,000	117,000,000	483,000,000	624,000,000		12,000,000	224,000,000	443,000,000	679,000,000	6,000,000	148,000,000	478,000,000	632,000,000	6,000,000	115,000,000	516,000,000	637,000,000	6,000,000	735,000,000	741,000,000	295,000,000	384,000,000	679,000,000	71,000,000	520,000,000	591,000,000	39,000,000	89,000,000	182,000,000	240,000,000	550,000,000	20,000,000	89,000,000	155,000,000	264,000,000
Initial investment in construction project									136,000,000			136,000,000																		109,000,000																			350,000,000
Costs as a percentage of total expenditures incurred since inception		100.00%				100.00%																									100.00%				100.00%									100.00%																							100.00%
Number of high-specification jackups purchased and under construction			2													1
Non-cash additions to property and equipment with corresponding increase to long-term debt																																																															716,000,000
Other capital expenditures																																																															19,000,000
Term of capital lease agreement (in years)																																																															20
Acquisition price of the drillship under capital lease agreement after completion of lease period																																																															1
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	$ 15,000,000

Drilling Fleet (Details 3) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended	12 Months Ended
	Jun. 30, 2010	Dec. 31, 2011	Dec. 31, 2010 drillingunit	Dec. 31, 2009
Dispositions
Net cash proceeds from sale of assets		$ 177	$ 60	$ 18
Gain (loss) on the sale of assets		4	257	(9)
Number of Midwater Floaters sold (in drilling units)			2
Unconsolidated affiliates
Net gain on sale of ownership interest				30
Net gain on sale of ownership interest per diluted share				$ 0.09
Loss of drilling unit
Proceeds from insurance recoveries for loss of drilling unit			560
Gain on loss of drilling unit	267		267
Gain loss on loss of drilling unit per diluted share			$ 0.83
Drilling and Oil Transportation Equipment
Dispositions
Net cash proceeds from sale of assets		163
Gain (loss) on the sale of assets		19
Gain (loss) on the sale of assets per diluted share		$ 0.06
Recognized gain (loss) on disposal of unrelated assets		(15)
Midwater Floaters
Dispositions
Net cash proceeds from sale of assets			38
Gain (loss) on the sale of assets			(15)
Gain (loss) on the sale of assets per diluted share			$ 0.04
Recognized gain (loss) on disposal of unrelated assets			5
Number of Midwater Floaters sold (in drilling units)			2
Number of notes receivable provided as Non-Cash proceeds from sale of assets			2
Non-cash proceeds in the form of notes receivable from sale of assets			165
Sale of Sedco 135-D
Dispositions
Net cash proceeds from sale of assets				18
Gain (loss) on the sale of assets				(9)
Gain (loss) on the sale of assets per diluted share				$ 0.03
Caspian Drilling Company Limited
Unconsolidated affiliates
Ownership interest in affiliate (as a percent)				45.00%
Net proceeds received for the exchange of ownership interest				4
Arab Drilling & Workover Company
Unconsolidated affiliates
Ownership interest in affiliate (as a percent)				40.00%
Net proceeds received for the exchange of ownership interest				38
Overseas Drilling Limited
Unconsolidated affiliates
Ownership interest in affiliate (as a percent)		50.00%
Net proceeds received for the exchange of ownership interest		22
Net gain on sale of ownership interest		$ 13
Net gain on sale of ownership interest per diluted share		$ 0.04

Goodwill and Other Intangible Assets (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2011	Dec. 31, 2011 Contract drilling services	Dec. 31, 2011 Drilling management services	Dec. 31, 2010 Drilling management services
Goodwill
Gross carrying amount at the beginning of the period		$ 10,802	$ 10,626	$ 176	$ 176
Business combination		273	273
Gross carrying amount at the end of the period	11,075	11,075	10,899	176	176
Goodwill Accumulated Impairment [Roll Forward]
Accumulated impairment at the beginning of the period		(2,670)	(2,494)	(176)	(176)
Impairment	(5,200)	(5,200)	(5,200)
Accumulated impairment at the end of the period	(7,870)	(7,870)	(7,694)	(176)	(176)
Goodwill Net of Impairment [Roll Forward]
Net carrying amount at the beginning of the period		8,132	8,132
Impairment	(5,200)	(5,200)	(5,200)
Business combination		273	273
Net carrying amount at the end of the period	$ 3,205	$ 3,205	$ 3,205

Goodwill and Other Intangible Assets (Details 2) (ADTI trade name, USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
ADTI trade name
Indefinite-lived intangible asset, gross, excluding goodwill
Gross carrying amount at the beginning of the period	$ 76	$ 76	$ 76
Gross carrying amount at the end of the period	76	76	76
Changes in accumulated impairment of indefinite-lived intangible assets
Accumulated impairment at the beginning of the period	(37)	(37)	(37)
Accumulated impairment at the end of the period	(37)	(37)	(37)
Net carrying amount at the beginning of the period	39	39
Net carrying amount at the end of the period	$ 39	$ 39

Goodwill and Other Intangible Assets (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Change in gross carrying amounts of definite-lived intangible assets
Gross carrying amount at the beginning of the period	$ 339	$ 339
Gross carrying amount at the end of the period	339	339
Changes in accumulated amortization and impairment of finite-lived intangible liabilities
Accumulated amortization and impairment at the beginning of the period	(274)	(251)
Amortization	(11)	(23)
Accumulated amortization and impairment at the end of the period	(285)	(274)
Net carrying amount at the beginning of the period	65	88
Net carrying amount at the end of the period	54	65
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
Gross carrying amount at the end of the period	191	191
Changes in accumulated amortization and impairment of finite-lived intangible liabilities
Accumulated amortization and impairment at the beginning of the period	(185)	(167)
Amortization	(6)	(18)
Accumulated amortization and impairment at the end of the period	(191)	(185)
Net carrying amount at the beginning of the period	6	24
Net carrying amount at the end of the period		6
Customer relationships
Change in gross carrying amounts of definite-lived intangible assets
Gross carrying amount at the beginning of the period	148	148
Gross carrying amount at the end of the period	148	148
Changes in accumulated amortization and impairment of finite-lived intangible liabilities
Accumulated amortization and impairment at the beginning of the period	(89)	(84)
Amortization	(5)	(5)
Accumulated amortization and impairment at the end of the period	(94)	(89)
Net carrying amount at the beginning of the period	59	64
Net carrying amount at the end of the period	54	59
Drilling contract intangible liabilities
Changes in accumulated amortization and impairment of finite-lived intangible liabilities
Accumulated amortization and impairment at the beginning of the period	(1,342)	(1,226)
Amortization	(51)	(116)
Accumulated amortization and impairment at the end of the period	(1,393)	(1,342)
Gross carrying amount at the beginning of the period	1,494	1,494
Gross carrying amount at the end of the period	1,494	1,494
Net carrying amount at the beginning of the year	152	268
Amortization	(51)	(116)
Net carrying amount at the end of the year	$ 101	$ 152

Goodwill and Other Intangible Assets (Details 4) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011
Drilling contract intangibles
Future amortization related to intangible assets and liabilities
2012	$ (41)
2013	(25)
2014	(15)
2015	(14)
2016	(6)
Total intangible assets (liabilities), net	(101)
Customer relationships
Definite-lived intangible assets and intangible liabilities
Amortization of intangible asset (in years)	15
Future amortization related to intangible assets and liabilities
2012	5
2013	5
2014	5
2015	5
2016	5
Thereafter	29
Total intangible assets (liabilities), net	$ 54

Debt (Details)	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							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
Debt (Details)	Dec. 31, 2009 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2011 NOK	Dec. 31, 2010 USD ($)	Dec. 31, 2010 ODL Loan Facility USD ($)	Dec. 31, 2011 Commercial paper program USD ($)	Dec. 31, 2010 Commercial paper program USD ($)	Apr. 15, 2011 6.625% Notes due April 2011	Dec. 31, 2010 6.625% Notes due April 2011 USD ($)	Apr. 30, 2001 6.625% Notes due April 2011 USD ($)	Dec. 31, 2011 5% Notes due February 2013 USD ($)	Dec. 31, 2010 5% Notes due February 2013 USD ($)	Dec. 31, 2011 5.25% Senior Notes due March 2013 USD ($)	Dec. 31, 2010 5.25% Senior Notes due March 2013 USD ($)	Dec. 31, 2011 TPDI Credit Facilities due March 2015 USD ($)	Dec. 31, 2010 TPDI Credit Facilities due March 2015 USD ($)	Dec. 31, 2011 4.95% Senior Notes due November 2015 USD ($)	Dec. 31, 2010 4.95% Senior Notes due November 2015 USD ($)	Sep. 30, 2010 4.95% Senior Notes due November 2015 USD ($)	Dec. 31, 2011 Aker Revolving Credit and Term Loan Facility due December 2015 USD ($)	Dec. 31, 2011 Aker Revolving Credit Facility due December 2015 USD ($)	Dec. 31, 2011 Aker Term Loan Facility due December 2015	Feb. 21, 2011 Aker Term Loan Facility due December 2015 USD ($)	Dec. 31, 2011 5.05% Senior Notes due December 2016 USD ($)	Dec. 31, 2011 Callable Bonds due February 2016 USD ($)	Dec. 31, 2011 FRN Callable Bonds USD ($)	Dec. 31, 2011 FRN Callable Bonds NOK	Feb. 21, 2011 FRN Callable Bonds NOK	Dec. 31, 2011 11% Callable Bonds USD ($)	Dec. 31, 2011 11% Callable Bonds NOK	Feb. 21, 2011 11% Callable Bonds NOK	Dec. 31, 2011 ADDCL Credit Facilities due December 2017 USD ($)	Dec. 31, 2010 ADDCL Credit Facilities due December 2017 USD ($)	Dec. 31, 2011 Eksportfinans notes due January 2018 USD ($)	Dec. 31, 2011 Eksportfinans Loan A USD ($)	Dec. 31, 2011 Eksportfinans Loan B USD ($)	Dec. 31, 2011 6.00% Senior Notes due March 2018 USD ($)	Dec. 31, 2010 6.00% Senior Notes due March 2018 USD ($)	Dec. 31, 2011 7.375% Senior Notes due April 2018 USD ($)	Dec. 31, 2010 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 ($)	Dec. 31, 2010 TPDI Notes due October 2019 USD ($)	Dec. 31, 2011 6.50% Senior Notes due November 2020 USD ($)	Dec. 31, 2010 6.50% Senior Notes due November 2020 USD ($)	Sep. 30, 2010 6.50% Senior Notes due November 2020 USD ($)	Dec. 31, 2011 6.375% Senior Notes due December 2021 USD ($)	Dec. 31, 2011 7.45% Notes due April 2027 USD ($)	Dec. 31, 2010 7.45% Notes due April 2027 USD ($)	Dec. 31, 2011 8% Debentures due April 2027 USD ($)	Dec. 31, 2010 8% Debentures due April 2027 USD ($)	Dec. 31, 2011 7% Notes due June 2028 USD ($)	Dec. 31, 2010 7% Notes due June 2028 USD ($)	Aug. 31, 2009 Capital lease contract due August 2029 USD ($)	Dec. 31, 2011 Capital lease contract due August 2029 USD ($)	Dec. 31, 2010 Capital lease contract due August 2029 USD ($)	Dec. 31, 2011 7.5% Notes due April 2031 USD ($)	Dec. 31, 2010 7.5% Notes due April 2031 USD ($)	Dec. 31, 2011 1.625% Series A, 1.50% Series B and 1.50% Series C Convertible Senior Notes USD ($) D	Dec. 31, 2011 1.625% Series A Convertible Senior Notes due December 2037	Dec. 31, 2010 1.625% Series A Convertible Senior Notes due December 2037 USD ($)	Dec. 31, 2007 1.625% Series A Convertible Senior Notes due December 2037 USD ($)	Dec. 31, 2011 1.50% Series B Convertible Senior Notes due December 2037 USD ($)	Dec. 31, 2010 1.50% Series B Convertible Senior Notes due December 2037 USD ($)	Dec. 31, 2007 1.50% Series B Convertible Senior Notes due December 2037 USD ($)	Dec. 31, 2011 1.50% Series C Convertible Senior Notes due December 2037 USD ($)	Dec. 31, 2010 1.50% Series C Convertible Senior Notes due December 2037 USD ($)	Dec. 31, 2007 1.50% Series C Convertible Senior Notes due December 2037 USD ($)	Dec. 31, 2011 6.80% Senior Notes due March 2038 USD ($)	Dec. 31, 2010 6.80% Senior Notes due March 2038 USD ($)	Dec. 31, 2011 7.35% Senior Notes due December 2041 USD ($)	Dec. 31, 2011 Five Year Revolving Credit Facility USD ($) numerator denominator	Dec. 31, 2011 Five Year Revolving Credit Facility Adjusted LIBOR	Dec. 31, 2011 Five Year Revolving Credit Facility Base Rate	Dec. 31, 2011 Transocean Ltd. and Subsidiaries USD ($)	Dec. 31, 2010 Transocean Ltd. and Subsidiaries USD ($)	Dec. 31, 2010 Transocean Ltd. and Subsidiaries ODL Loan Facility USD ($)	Dec. 31, 2010 Transocean Ltd. and Subsidiaries Commercial paper program USD ($)	Dec. 31, 2010 Transocean Ltd. and Subsidiaries 6.625% Notes due April 2011 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 5% Notes due February 2013 USD ($)	Dec. 31, 2010 Transocean Ltd. and Subsidiaries 5% Notes due February 2013 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 5.25% Senior Notes due March 2013 USD ($)	Dec. 31, 2010 Transocean Ltd. and Subsidiaries 5.25% Senior Notes due March 2013 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 4.95% Senior Notes due November 2015 USD ($)	Dec. 31, 2010 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, 2011 Transocean Ltd. and Subsidiaries 5.05% Senior Notes due December 2016 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries Callable Bonds due February 2016 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries Eksportfinans notes due January 2018 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 6.00% Senior Notes due March 2018 USD ($)	Dec. 31, 2010 Transocean Ltd. and Subsidiaries 6.00% Senior Notes due March 2018 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 7.375% Senior Notes due April 2018 USD ($)	Dec. 31, 2010 Transocean Ltd. and Subsidiaries 7.375% Senior Notes due April 2018 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 6.50% Senior Notes due November 2020 USD ($)	Dec. 31, 2010 Transocean Ltd. and Subsidiaries 6.50% Senior Notes due November 2020 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 6.375% Senior Notes due December 2021 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 7.45% Notes due April 2027 USD ($)	Dec. 31, 2010 Transocean Ltd. and Subsidiaries 7.45% Notes due April 2027 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 8% Debentures due April 2027 USD ($)	Dec. 31, 2010 Transocean Ltd. and Subsidiaries 8% Debentures due April 2027 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 7% Notes due June 2028 USD ($)	Dec. 31, 2010 Transocean Ltd. and Subsidiaries 7% Notes due June 2028 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries Capital lease contract due August 2029 USD ($)	Dec. 31, 2010 Transocean Ltd. and Subsidiaries Capital lease contract due August 2029 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 7.5% Notes due April 2031 USD ($)	Dec. 31, 2010 Transocean Ltd. and Subsidiaries 7.5% Notes due April 2031 USD ($)	Dec. 31, 2010 Transocean Ltd. and Subsidiaries 1.625% Series A Convertible Senior Notes due December 2037 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 1.50% Series B Convertible Senior Notes due December 2037 USD ($)	Dec. 31, 2010 Transocean Ltd. and Subsidiaries 1.50% Series B 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, 2010 Transocean Ltd. and Subsidiaries 1.50% Series C Convertible Senior Notes due December 2037 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 6.80% Senior Notes due March 2038 USD ($)	Dec. 31, 2010 Transocean Ltd. and Subsidiaries 6.80% Senior Notes due March 2038 USD ($)	Dec. 31, 2011 Transocean Ltd. and Subsidiaries 7.35% Senior Notes due December 2041 USD ($)	Dec. 31, 2011 Wholly-owned subsidiaries 5% Notes due February 2013 USD ($) subsidiary	Dec. 31, 2011 Wholly-owned subsidiaries 7% Notes due June 2028 USD ($) subsidiary	Dec. 31, 2011 Transocean Inc.	Dec. 31, 2011 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, 2011 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, 2011 Transocean Inc. 7.45% Notes due April 2027 USD ($)	Apr. 30, 1997 Transocean Inc. 7.45% Notes due April 2027 USD ($)	Dec. 31, 2011 Transocean Inc. 8% Debentures due April 2027 USD ($)	Apr. 30, 1997 Transocean Inc. 8% Debentures due April 2027 USD ($)	Dec. 31, 2011 Transocean Inc. 7.5% Notes due April 2031 USD ($)	Apr. 30, 2001 Transocean Inc. 7.5% Notes due April 2031 USD ($)	Dec. 31, 2011 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, 2011 Consolidated variable interest entities USD ($)	Dec. 31, 2010 Consolidated variable interest entities USD ($)	Dec. 31, 2011 Consolidated variable interest entities TPDI Credit Facilities due March 2015 USD ($)	Dec. 31, 2010 Consolidated variable interest entities TPDI Credit Facilities due March 2015 USD ($)	Dec. 31, 2011 Consolidated variable interest entities ADDCL Credit Facilities due December 2017 USD ($)	Dec. 31, 2010 Consolidated variable interest entities ADDCL Credit Facilities due December 2017 USD ($)	Dec. 31, 2011 Consolidated variable interest entities TPDI Notes due October 2019 USD ($)	Dec. 31, 2010 Consolidated variable interest entities TPDI Notes due October 2019 USD ($)	Dec. 31, 2011 TPDI TPDI Credit Facilities due March 2015 USD ($)	Dec. 31, 2010 TPDI TPDI Credit Facilities due March 2015 USD ($)	Dec. 31, 2011 TPDI TPDI Credit Facilities Senior Term Loan Due March 2015 USD ($)	Dec. 31, 2011 TPDI TPDI Credit Facilities Junior Term Loan Due March 2015 USD ($)	Dec. 31, 2011 TPDI TPDI Credit Facilities Revolving Credit Facility Due March 2015 USD ($)	Dec. 31, 2011 TPDI TPDI Notes due October 2019 USD ($) shareholder	Dec. 31, 2011 TPDI Uncommitted Credit Facility Established by Subsidiary USD ($)	Dec. 31, 2011 ADDCL ADDCL Credit Facilities Tranche A Due November 2017 USD ($)	Dec. 31, 2011 ADDCL ADDCL Credit Facilities Tranche C Due November 2017 USD ($)	Dec. 31, 2011 ADDCL ADDCL Secondary Loan Facility Due December 2015 USD ($)	Dec. 31, 2010 ADDCL ADDCL Secondary Loan Facility Due December 2015 USD ($)
Long-term debt by current and noncurrent
Total debt		$ 13,536,000,000		$ 11,221,000,000	$ 10,000,000		$ 88,000,000		$ 167,000,000		$ 253,000,000	$ 255,000,000	$ 507,000,000	$ 511,000,000	$ 473,000,000	$ 560,000,000	$ 1,120,000,000	$ 1,099,000,000		$ 594,000,000				$ 999,000,000	$ 267,000,000							$ 217,000,000	$ 242,000,000	$ 884,000,000			$ 998,000,000	$ 997,000,000	$ 247,000,000	$ 247,000,000		$ 148,000,000	$ 148,000,000	$ 899,000,000	$ 899,000,000		$ 1,199,000,000	$ 97,000,000	$ 96,000,000	$ 57,000,000	$ 57,000,000	$ 311,000,000	$ 313,000,000		$ 676,000,000	$ 694,000,000	$ 598,000,000	$ 598,000,000			$ 11,000,000		$ 30,000,000	$ 1,625,000,000		$ 1,663,000,000	$ 1,605,000,000		$ 999,000,000	$ 999,000,000	$ 300,000,000				$ 12,698,000,000	$ 10,271,000,000	$ 10,000,000	$ 88,000,000	$ 167,000,000	$ 253,000,000	$ 255,000,000	$ 507,000,000	$ 511,000,000	$ 1,120,000,000	$ 1,099,000,000	$ 594,000,000	$ 999,000,000	$ 267,000,000	$ 884,000,000	$ 998,000,000	$ 997,000,000	$ 247,000,000	$ 247,000,000	$ 899,000,000	$ 899,000,000	$ 1,199,000,000	$ 97,000,000	$ 96,000,000	$ 57,000,000	$ 57,000,000	$ 311,000,000	$ 313,000,000	$ 676,000,000	$ 694,000,000	$ 598,000,000	$ 598,000,000	$ 11,000,000	$ 30,000,000	$ 1,625,000,000	$ 1,663,000,000	$ 1,605,000,000	$ 999,000,000	$ 999,000,000	$ 300,000,000																$ 838,000,000	$ 950,000,000	$ 473,000,000	$ 560,000,000	$ 217,000,000	$ 242,000,000	$ 148,000,000	$ 148,000,000
Debt due within one year		2,039,000,000		2,012,000,000	10,000,000		88,000,000		167,000,000						70,000,000	70,000,000				90,000,000												27,000,000	25,000,000	142,000,000																					17,000,000	16,000,000					11,000,000		30,000,000	1,625,000,000		1,663,000,000									1,942,000,000	1,917,000,000	10,000,000	88,000,000	167,000,000							90,000,000			142,000,000														17,000,000	16,000,000			11,000,000	30,000,000	1,625,000,000	1,663,000,000																				97,000,000	95,000,000	70,000,000	70,000,000	27,000,000	25,000,000
Long-term debt		11,497,000,000		9,209,000,000																																																																							10,756,000,000	8,354,000,000																																																						741,000,000	855,000,000
Debt instrument interest rate stated percentage								6.625%			5.00%		5.25%				4.95%							5.05%					11.00%	11.00%				4.15%			6.00%		7.375%					6.50%			6.375%	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
Scheduled maturities of debt
2012		2,098,000,000																																																																									2,001,000,000																																																							97,000,000
2013		1,100,000,000																																																																									1,002,000,000																																																							98,000,000
2014		334,000,000																																																																									235,000,000																																																							99,000,000
2015		1,653,000,000																																																																									1,331,000,000																																																							322,000,000
2016		1,730,000,000																																																																									1,696,000,000																																																							34,000,000
Thereafter		6,638,000,000																																																																									6,450,000,000																																																							188,000,000
Total debt, excluding unamortized discounts, premiums and fair value adjustments		13,553,000,000																																																																									12,715,000,000																																																							838,000,000
Total unamortized discounts, premiums and fair value adjustments		(17,000,000)																																																																									(17,000,000)
Total debt		13,536,000,000		11,221,000,000	10,000,000		88,000,000		167,000,000		253,000,000	255,000,000	507,000,000	511,000,000	473,000,000	560,000,000	1,120,000,000	1,099,000,000		594,000,000				999,000,000	267,000,000							217,000,000	242,000,000	884,000,000			998,000,000	997,000,000	247,000,000	247,000,000		148,000,000	148,000,000	899,000,000	899,000,000		1,199,000,000	97,000,000	96,000,000	57,000,000	57,000,000	311,000,000	313,000,000		676,000,000	694,000,000	598,000,000	598,000,000			11,000,000		30,000,000	1,625,000,000		1,663,000,000	1,605,000,000		999,000,000	999,000,000	300,000,000				12,698,000,000	10,271,000,000	10,000,000	88,000,000	167,000,000	253,000,000	255,000,000	507,000,000	511,000,000	1,120,000,000	1,099,000,000	594,000,000	999,000,000	267,000,000	884,000,000	998,000,000	997,000,000	247,000,000	247,000,000	899,000,000	899,000,000	1,199,000,000	97,000,000	96,000,000	57,000,000	57,000,000	311,000,000	313,000,000	676,000,000	694,000,000	598,000,000	598,000,000	11,000,000	30,000,000	1,625,000,000	1,663,000,000	1,605,000,000	999,000,000	999,000,000	300,000,000																838,000,000	950,000,000	473,000,000	560,000,000	217,000,000	242,000,000	148,000,000	148,000,000
Credit facility term (in years)						5 years																																																																		5 years
Borrowing capacity, maximum						1,500,000,000															500,000,000																																																			2,000,000,000																																																																		1,265,000,000				75,000,000			215,000,000	399,000,000	90,000,000
Weighted-average interest rate (as a percent)																				3.00%																																																																																																																						2.20%							1.50%		3.70%
Debt instrument face amount										700,000,000									1,100,000,000				400,000,000	1,000,000,000				940,000,000			560,000,000										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																					LIBOR	LIBOR				Norwegian Interbank Offered Rate	Norwegian Interbank Offered Rate																																														LIBOR	Base Rate																																																																		LIBOR	LIBOR	LIBOR			LIBOR		LIBOR
Spread on variable rate basis (as a percent)																					2.50%	2.50%				7.00%	7.00%																																														1.625%																																																																			1.45%	2.25%	1.45%			0.725%
Percentage reduction to the calculated variable rate																																																																										1.00%
Minimum facility fee on the daily amount of five-year revolving credit facility (as a percent)																																																																								0.13%
Maximum facility fee on the daily amount of five-year revolving credit facility (as a percent)																																																																								0.33%
Commitment fee percentage at period end																																																																								0.275%
Maximum debt to tangible capitalization ratio, numerator																																																																								0.6
Maximum debt to tangible capitalization ratio, denominator																																																																								1.0
Credit facility available borrowing capacity																																																																								2,000,000,000
Letters of credit issued and outstanding																																																																								24,000,000																																																																								60,000,000
Number of wholly-owned subsidiaries which are obligors to debt instrument																																																																																																																			2	2
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%
Principal amount outstanding																	1,100,000,000							1,000,000,000		158,000,000	940,000,000		94,000,000	560,000,000					427,000,000	462,000,000			246,000,000					900,000,000			1,200,000,000														11,000,000		30,000,000	1,680,000,000		1,722,000,000	1,722,000,000				300,000,000																																												250,000,000	300,000,000		500,000,000		1,000,000,000		100,000,000		57,000,000		600,000,000		1,000,000,000															296,000,000		190,000,000
Aggregate commitment of subsidiary in secured term loan															595,000,000
Credit facility amount outstanding																				594,000,000																																																																																																																						945,000,000									78,000,000
Debt due to a subsidiary, eliminated in consolidation																																																																																																																																										472,000,000					148,000,000			399,000,000	51,000,000
Restricted investments used as security for debt instruments																																		889,000,000																																																																																																								23,000,000	23,000,000								16,000,000	16,000,000
NOK exchange rate			5.9631
Percentage of total commitment under ADDCL secondary bank credit agreement provided by subsidiary																																																																																																																																																			65.00%
Spread on variable rate basis, low end of range (as a percent)																																																																																																																																																			3.125%
Spread on variable rate basis, high end of range (as a percent)																																																																																																																																																			5.125%
Fixed interest rate on restricted cash investments (as a percent)																																		4.15%
Number of shareholders to which TPDI has issued promissory notes																																																																																																																																															2
Weighted-average interest rate (as a percent)																																																																																																																																															2.50%
Implicit interest rate (as a percent)																																																							7.80%
Non-cash capital additions recorded upon entry into capital lease																																																						716,000,000
Asset capitalized under capital leases	$ 716,000,000																																																					$ 716,000,000
Conversion rate per $1000 principal amount																																																											6.1902
Convertible debt, principal amount, basis for conversion																																																											1,000
Conversion price per share of common stock																																																											$ 161.55
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 (in days)																																																											30
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
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
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%

Debt (Details 2) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended			12 Months Ended	1 Months Ended	12 Months Ended		37 Months Ended	12 Months Ended						1 Months Ended
	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2011	Dec. 31, 2011 1.625% Series A, 1.50% Series B and 1.50% Series C Convertible Senior Notes	Jan. 31, 2011 1.625% Series A Convertible Senior Notes due December 2037	Dec. 31, 2010 1.625% Series A Convertible Senior Notes due December 2037	Dec. 31, 2009 1.625% Series A Convertible Senior Notes due December 2037	Dec. 31, 2010 1.625% Series A 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, 2009 1.50% Series B Convertible Senior Notes due December 2037	Dec. 31, 2011 1.50% Series C Convertible Senior Notes due December 2037 Y	Dec. 31, 2010 1.50% Series C Convertible Senior Notes due December 2037	Dec. 31, 2009 1.50% Series C Convertible Senior Notes due December 2037	Jan. 31, 2012 Debt 1.50% Series B Convertible Senior Notes due December 2037
Carrying amounts of Convertible Senior Notes
Principal amount outstanding						$ 11		$ 11	$ 30	$ 1,680		$ 1,722	$ 1,722
Unamortized discount										(55)		(59)	(117)
Total debt	11,221		13,536			11		11	30	1,625		1,663	1,605
Carrying amount of equity component						1		1	4	210		276	276
Convertible debt instrument effective interest rate (as a percent)												5.28%
Remaining period over which discount will be amortized (in years)												1
Interest expense						58	85		78	98	100	84	98	100
Aggregate principal amount of debt repurchased							901	1,288	1,700				478
Aggregate cash payment made for debt repurchased					11		865	1,288	1,700				453		30
Gain (loss) on retirement of debt	33	29					28						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							$ 22						$ 8
Shares per note of Convertible Senior Notes				1,000

Derivatives and Hedging (Details) In Millions, unless otherwise specified				12 Months Ended
	Dec. 31, 2011 4.95% Senior Notes due November 2015	Dec. 31, 2011 5.25% Senior Notes due March 2013	Dec. 31, 2011 5% Notes due February 2013	Dec. 31, 2011 Interest rate swaps Derivatives designated as hedging instruments subsidiary	Dec. 31, 2011 Interest rate swaps Derivative not designated as hedging instruments USD ($)	Dec. 31, 2011 Interest rate swaps 4.95% Senior Notes due November 2015 Derivatives designated as hedging instruments	Dec. 31, 2011 Interest rate swaps 5.25% Senior Notes due March 2013 Derivatives designated as hedging instruments	Dec. 31, 2011 Interest rate swaps 5% Notes due February 2013 Derivatives designated as hedging instruments	Dec. 31, 2011 Interest rate swaps Fair value hedges Derivatives designated as hedging instruments USD ($)	Dec. 31, 2011 Interest rate swaps Cash flow hedges Derivatives designated as hedging instruments USD ($)	Dec. 31, 2011 Cross-currency swaps Cash flow hedges Derivatives designated as hedging instruments USD ($)	Dec. 31, 2011 Cross-currency swaps Cash flow hedges Derivatives designated as hedging instruments NOK
Derivatives and Hedging
Number of wholly owned subsidiaries in interest rate swap agreements				2
Derivative, underlying risk				interest rate
Derivative, hedge designation				fair value
Interest rate on notes hedged to reduce exposure to changes in fair value (as a percent)	4.95%	5.25%	5.00%			4.95%	5.25%	5.00%
Interest rate description to determine the variable interest on debt hedged				three-month LIBOR
Aggregate notional amount					$ 305				$ 1,400	$ 455
Weighted average variable rate (as a percent)					0.50%				3.70%	0.60%
Weighted average fixed rate (as a percent)					4.20%				5.10%	2.30%
Notional amount, pay											102
Notional amount, receive												560
Weighted average fixed rate, pay (as a percent)											8.90%	8.90%
Weighted average fixed rate, receive (as a percent)											11.00%	11.00%

Derivatives and Hedging (Details 2) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Other current assets \| Derivatives designated as hedging instruments
Aggregate carrying amount of derivatives
Interest rate swaps, fair value hedges	$ 5	$ 4
Other assets \| Derivatives designated as hedging instruments
Aggregate carrying amount of derivatives
Interest rate swaps, fair value hedges	31	17
Other long-term liabilities \| Derivatives designated as hedging instruments
Aggregate carrying amount of derivatives
Interest rate swaps, cash flow hedges	16	13
Cross-currency swaps, cash flow hedges	7
Other long-term liabilities \| Nondesignated
Aggregate carrying amount of derivatives
Interest rate swaps not designated as hedging instruments	$ 15

Derivatives and Hedging (Details 3) (Derivatives designated as hedging instruments, USD $) In Millions, unless otherwise specified	1 Months Ended		12 Months Ended
	Oct. 31, 2011	Oct. 03, 2011	Dec. 31, 2011 Interest rate swaps Interest expense, net of amounts capitalized	Dec. 31, 2010 Interest rate swaps Interest expense, net of amounts capitalized
Effect on statement of operations resulting from changes in the fair values of derivatives designated as cash flow hedges
Loss associated with effective portion			$ 11	$ 12
Liability amount for other undesignated derivative instruments acquired, measured at fair value		12
Cash payment for termination of other undesignated derivative instruments	15
Loss on the termination of other undesignated derivative instruments	$ 3

Derivatives and Hedging (Details 4) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Sep. 30, 2011 USD ($)	Dec. 31, 2011 Derivative not designated as hedging instruments Forward exchange contract USD ($) exchangerate	Dec. 31, 2011 Derivative not designated as hedging instruments Forward exchange contract NOK
Derivative instruments
Exchange rate		5.4005
Aggregate notional amount, pay		$ 1,120
Aggregate notional amount, receive			6,051
Loss recognized during the period	$ 78	$ 78

Postemployment Benefit Plans (Details) (USD $)	12 Months Ended
Postemployment Benefit Plans (Details) (USD $)	Dec. 31, 2011 plan	Dec. 31, 2010	Dec. 31, 2009
Change in projected benefit obligation
Projected benefit obligation, beginning of period	$ 1,498,000,000	$ 1,389,000,000
Assumed projected benefit obligation	17,000,000
Actuarial (gains) losses, net	149,000,000	45,000,000
Service cost	65,000,000	63,000,000
Interest cost	83,000,000	77,000,000
Foreign currency exchange rate	(1,000,000)	(13,000,000)
Benefits paid	(54,000,000)	(70,000,000)
Participant contributions	3,000,000	3,000,000
Special termination benefits		3,000,000
Settlements and curtailments		1,000,000
Projected benefit obligation, end of period	1,760,000,000	1,498,000,000
Change in plan assets
Fair value of plan assets, beginning of period	1,029,000,000	875,000,000
Fair value of acquired plan assets	9,000,000
Actual return on plan assets	31,000,000	114,000,000
Foreign currency exchange rate changes	2,000,000	(11,000,000)
Employer contributions	103,000,000	118,000,000
Participant contributions	3,000,000	3,000,000
Benefits paid	(54,000,000)	(70,000,000)
Settlement and curtailments	(3,000,000)
Fair value of plan assets, end of period	1,120,000,000	1,029,000,000
Funded status, end of period	(640,000,000)	(469,000,000)
Balance sheet classification, end of period:
Pension asset, non-current		(8,000,000)
Accrued pension liability, current	11,000,000	9,000,000
Accrued pension liability, non-current	629,000,000	468,000,000
Accumulated other comprehensive income (loss)	(550,000,000)	(371,000,000)
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	1,760,000,000	1,414,000,000
Fair value of plan assets	1,120,000,000	945,000,000
Accumulated benefit obligation	1,500,000,000	1,300,000,000
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	1,424,000,000	1,246,000,000
Fair value of plan assets	1,023,000,000	945,000,000
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)	4.66%	5.48%
Compensation trend rate (as a percent)	4.22%	4.24%
Weighted-average assumptions used to determine net periodic benefit costs
Discount rate (as a percent)	5.49%	5.86%	5.41%
Expected rate of return (as a percent)	8.49%	8.49%	8.50%
Compensation trend rate (as a percent)	4.24%	4.21%	4.21%
Change in projected benefit obligation
Projected benefit obligation, beginning of period	1,068,000,000	932,000,000
Actuarial (gains) losses, net	128,000,000	89,000,000
Service cost	43,000,000	42,000,000	44,000,000
Interest cost	58,000,000	54,000,000	50,000,000
Benefits paid	(37,000,000)	(51,000,000)
Special termination benefits		(3,000,000)
Settlements and curtailments		(1,000,000)
Projected benefit obligation, end of period	1,260,000,000	1,068,000,000	932,000,000
Change in plan assets
Fair value of plan assets, beginning of period	697,000,000	594,000,000
Actual return on plan assets	39,000,000	85,000,000
Employer contributions	70,000,000	69,000,000
Benefits paid	(37,000,000)	(51,000,000)
Fair value of plan assets, end of period	769,000,000	697,000,000	594,000,000
Funded status, end of period	(491,000,000)	(371,000,000)
Balance sheet classification, end of period:
Accrued pension liability, current	3,000,000	3,000,000
Accrued pension liability, non-current	488,000,000	368,000,000
Accumulated other comprehensive income (loss)	(437,000,000)	(308,000,000)
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	1,260,000,000	1,068,000,000
Fair value of plan assets	769,000,000	697,000,000
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	1,083,000,000	921,000,000
Fair value of plan assets	769,000,000	697,000,000
Non-U.S. Plans
Postemployment Benefit Plans
Number of funded defined benefit plans assumed in mergers and acquisitions	3
Number of unfunded defined benefit plans	2
Weighted average assumptions used to determine benefit obligations
Discount rate (as a percent)	4.90%	5.81%
Compensation trend rate (as a percent)	4.30%	4.65%
Weighted-average assumptions used to determine net periodic benefit costs
Discount rate (as a percent)	5.73%	5.67%	6.06%
Expected rate of return (as a percent)	6.42%	6.65%	6.59%
Compensation trend rate (as a percent)	4.62%	4.77%	4.55%
Change in projected benefit obligation
Projected benefit obligation, beginning of period	374,000,000	403,000,000
Assumed projected benefit obligation	17,000,000
Actuarial (gains) losses, net	24,000,000	(46,000,000)
Service cost	21,000,000	20,000,000	18,000,000
Interest cost	22,000,000	20,000,000	17,000,000
Foreign currency exchange rate	(1,000,000)	(13,000,000)
Benefits paid	(12,000,000)	(14,000,000)
Participant contributions	2,000,000	2,000,000
Settlements and curtailments		2,000,000
Projected benefit obligation, end of period	447,000,000	374,000,000	403,000,000
Change in plan assets
Fair value of plan assets, beginning of period	332,000,000	281,000,000
Fair value of acquired plan assets	9,000,000
Actual return on plan assets	(8,000,000)	29,000,000
Foreign currency exchange rate changes	2,000,000	(11,000,000)
Employer contributions	29,000,000	45,000,000
Participant contributions	2,000,000	2,000,000
Benefits paid	(12,000,000)	(14,000,000)
Settlement and curtailments	(3,000,000)
Fair value of plan assets, end of period	351,000,000	332,000,000	281,000,000
Funded status, end of period	(96,000,000)	(42,000,000)
Balance sheet classification, end of period:
Pension asset, non-current		(8,000,000)
Accrued pension liability, current	5,000,000	2,000,000
Accrued pension liability, non-current	91,000,000	48,000,000
Accumulated other comprehensive income (loss)	(111,000,000)	(61,000,000)
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	447,000,000	290,000,000
Fair value of plan assets	351,000,000	248,000,000
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	288,000,000	269,000,000
Fair value of plan assets	254,000,000	248,000,000
OPEB Plans
Weighted average assumptions used to determine benefit obligations
Discount rate (as a percent)	4.28%	4.92%
Weighted-average assumptions used to determine net periodic benefit costs
Discount rate (as a percent)	4.94%	5.51%	5.34%
Health care cost trend rate, initial (as a percent)	8.08%	8.00%	8.99%
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	56,000,000	54,000,000
Actuarial (gains) losses, net	(3,000,000)	2,000,000
Service cost	1,000,000	1,000,000
Interest cost	3,000,000	3,000,000
Benefits paid	(5,000,000)	(5,000,000)
Participant contributions	1,000,000	1,000,000
Projected benefit obligation, end of period	53,000,000	56,000,000	54,000,000
Change in plan assets
Employer contributions	4,000,000	4,000,000
Participant contributions	1,000,000	1,000,000
Benefits paid	(5,000,000)	(5,000,000)
Funded status, end of period	(53,000,000)	(56,000,000)
Balance sheet classification, end of period:
Accrued pension liability, current	3,000,000	4,000,000
Accrued pension liability, non-current	50,000,000	52,000,000
Accumulated other comprehensive income (loss)	(2,000,000)	(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	53,000,000	56,000,000
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	$ 53,000,000	$ 56,000,000

Postemployment Benefit Plans (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Fair value of plan assets
Total investments	$ 1,120	$ 1,029	$ 875
Transocean Plans
Fair value of plan assets
Total investments	1,120	1,029
Transocean Plans \| Significant observable inputs
Fair value of plan assets
Total investments	805	726
Transocean Plans \| Significant other observable inputs
Fair value of plan assets
Total investments	315	303
Transocean Plans \| Equity securities
Fair value of plan assets
Total investments	654	628
Transocean Plans \| Equity securities \| Significant observable inputs
Fair value of plan assets
Total investments	486	450
Transocean Plans \| Equity securities \| Significant other observable inputs
Fair value of plan assets
Total investments	168	178
Transocean Plans \| U.S. equity securities
Fair value of plan assets
Total investments	424	387
Transocean Plans \| U.S. equity securities \| Significant observable inputs
Fair value of plan assets
Total investments	395	359
Transocean Plans \| U.S. equity securities \| Significant other observable inputs
Fair value of plan assets
Total investments	29	28
Transocean Plans \| Non-U.S. equity securities
Fair value of plan assets
Total investments	230	241
Transocean Plans \| Non-U.S. equity securities \| Significant observable inputs
Fair value of plan assets
Total investments	91	91
Transocean Plans \| Non-U.S. equity securities \| Significant other observable inputs
Fair value of plan assets
Total investments	139	150
Transocean Plans \| Fixed income securities
Fair value of plan assets
Total investments	321	275
Transocean Plans \| Fixed income securities \| Significant observable inputs
Fair value of plan assets
Total investments	278	241
Transocean Plans \| Fixed income securities \| Significant other observable inputs
Fair value of plan assets
Total investments	43	34
Transocean Plans \| U.S. government
Fair value of plan assets
Total investments	52	59
Transocean Plans \| U.S. government \| Significant observable inputs
Fair value of plan assets
Total investments	52	59
Transocean Plans \| U.S. corporate
Fair value of plan assets
Total investments	9	175
Transocean Plans \| U.S. corporate \| Significant observable inputs
Fair value of plan assets
Total investments	9	175
Transocean Plans \| Non U.S. government
Fair value of plan assets
Total investments	221	34
Transocean Plans \| Non U.S. government \| Significant observable inputs
Fair value of plan assets
Total investments	178
Transocean Plans \| Non U.S. government \| Significant other observable inputs
Fair value of plan assets
Total investments	43	34
Transocean Plans \| Non U.S. corporate
Fair value of plan assets
Total investments	39	7
Transocean Plans \| Non U.S. corporate \| Significant observable inputs
Fair value of plan assets
Total investments	39	7
Transocean Plans \| Other investments
Fair value of plan assets
Total investments	145	126
Transocean Plans \| Other investments \| Significant observable inputs
Fair value of plan assets
Total investments	41	35
Transocean Plans \| Other investments \| Significant other observable inputs
Fair value of plan assets
Total investments	104	91
Transocean Plans \| Cash
Fair value of plan assets
Total investments	41	35
Transocean Plans \| Cash \| Significant observable inputs
Fair value of plan assets
Total investments	41	35
Transocean Plans \| Property
Fair value of plan assets
Total investments	8	7
Transocean Plans \| Property \| Significant other observable inputs
Fair value of plan assets
Total investments	8	7
Transocean Plans \| Investment contracts
Fair value of plan assets
Total investments	96	84
Transocean Plans \| Investment contracts \| Significant other observable inputs
Fair value of plan assets
Total investments	96	84
U.S. Plans
Weighted-average target allocations of the investments
Target allocation percentage, equity securities	65.00%
Target allocation percentage, fixed income securities	35.00%
Total target allocation percentage	100.00%
Weighted-average actual allocations of the investments
Actual allocation percentage, equity securities	64.00%	65.00%
Actual allocation percentage, fixed income securities	36.00%	34.00%
Actual allocation percentage, other investments		1.00%
Total actual allocation percentage	100.00%	100.00%
Fair value of plan assets
Total investments	769	697	594
U.S. Plans \| Significant observable inputs
Fair value of plan assets
Total investments	767	695
U.S. Plans \| Significant other observable inputs
Fair value of plan assets
Total investments	2	2
U.S. Plans \| Equity securities
Fair value of plan assets
Total investments	488	452
U.S. Plans \| Equity securities \| Significant observable inputs
Fair value of plan assets
Total investments	486	450
U.S. Plans \| Equity securities \| Significant other observable inputs
Fair value of plan assets
Total investments	2	2
U.S. Plans \| U.S. equity securities
Fair value of plan assets
Total investments	395	359
U.S. Plans \| U.S. equity securities \| Significant observable inputs
Fair value of plan assets
Total investments	395	359
U.S. Plans \| Non-U.S. equity securities
Fair value of plan assets
Total investments	93	93
U.S. Plans \| Non-U.S. equity securities \| Significant observable inputs
Fair value of plan assets
Total investments	91	91
U.S. Plans \| Non-U.S. equity securities \| Significant other observable inputs
Fair value of plan assets
Total investments	2	2
U.S. Plans \| Fixed income securities
Fair value of plan assets
Total investments	278	241
U.S. Plans \| Fixed income securities \| Significant observable inputs
Fair value of plan assets
Total investments	278	241
U.S. Plans \| U.S. government
Fair value of plan assets
Total investments	52	59
U.S. Plans \| U.S. government \| Significant observable inputs
Fair value of plan assets
Total investments	52	59
U.S. Plans \| U.S. corporate
Fair value of plan assets
Total investments	9	175
U.S. Plans \| U.S. corporate \| Significant observable inputs
Fair value of plan assets
Total investments	9	175
U.S. Plans \| Non U.S. government
Fair value of plan assets
Total investments	178
U.S. Plans \| Non U.S. government \| Significant observable inputs
Fair value of plan assets
Total investments	178
U.S. Plans \| Non U.S. corporate
Fair value of plan assets
Total investments	39	7
U.S. Plans \| Non U.S. corporate \| Significant observable inputs
Fair value of plan assets
Total investments	39	7
U.S. Plans \| Other investments
Fair value of plan assets
Total investments	3	4
U.S. Plans \| Other investments \| Significant observable inputs
Fair value of plan assets
Total investments	3	4
U.S. Plans \| Cash
Fair value of plan assets
Total investments	3	4
U.S. Plans \| Cash \| Significant observable inputs
Fair value of plan assets
Total investments	3	4
Non-U.S. Plans
Weighted-average target allocations of the investments
Target allocation percentage, equity securities	51.00%
Target allocation percentage, fixed income securities	14.00%
Target allocation percentage, other investments	35.00%
Total target allocation percentage	100.00%
Weighted-average actual allocations of the investments
Actual allocation percentage, equity securities	47.00%	53.00%
Actual allocation percentage, fixed income securities	12.00%	10.00%
Actual allocation percentage, other investments	41.00%	37.00%
Total actual allocation percentage	100.00%	100.00%
Fair value of plan assets
Total investments	351	332	281
Non-U.S. Plans \| Significant observable inputs
Fair value of plan assets
Total investments	38	31
Non-U.S. Plans \| Significant other observable inputs
Fair value of plan assets
Total investments	313	301
Non-U.S. Plans \| Equity securities
Fair value of plan assets
Total investments	166	176
Non-U.S. Plans \| Equity securities \| Significant other observable inputs
Fair value of plan assets
Total investments	166	176
Non-U.S. Plans \| U.S. equity securities
Fair value of plan assets
Total investments	29	28
Non-U.S. Plans \| U.S. equity securities \| Significant other observable inputs
Fair value of plan assets
Total investments	29	28
Non-U.S. Plans \| Non-U.S. equity securities
Fair value of plan assets
Total investments	137	148
Non-U.S. Plans \| Non-U.S. equity securities \| Significant other observable inputs
Fair value of plan assets
Total investments	137	148
Non-U.S. Plans \| Fixed income securities
Fair value of plan assets
Total investments	43	34
Non-U.S. Plans \| Fixed income securities \| Significant other observable inputs
Fair value of plan assets
Total investments	43	34
Non-U.S. Plans \| Non U.S. government
Fair value of plan assets
Total investments	43	34
Non-U.S. Plans \| Non U.S. government \| Significant other observable inputs
Fair value of plan assets
Total investments	43	34
Non-U.S. Plans \| Other investments
Fair value of plan assets
Total investments	142	122
Non-U.S. Plans \| Other investments \| Significant observable inputs
Fair value of plan assets
Total investments	38	31
Non-U.S. Plans \| Other investments \| Significant other observable inputs
Fair value of plan assets
Total investments	104	91
Non-U.S. Plans \| Cash
Fair value of plan assets
Total investments	38	31
Non-U.S. Plans \| Cash \| Significant observable inputs
Fair value of plan assets
Total investments	38	31
Non-U.S. Plans \| Property
Fair value of plan assets
Total investments	8	7
Non-U.S. Plans \| Property \| Significant other observable inputs
Fair value of plan assets
Total investments	8	7
Non-U.S. Plans \| Investment contracts
Fair value of plan assets
Total investments	96	84
Non-U.S. Plans \| Investment contracts \| Significant other observable inputs
Fair value of plan assets
Total investments	$ 96	$ 84

Postemployment Benefit Plans (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Net periodic benefit costs, before tax
Service cost	$ 65	$ 63
Interest cost	83	77
Special termination benefits		3
Net periodic benefit costs	88	91	87
Unrecognized accumulated other comprehensive income, before tax
Actuarial loss, net	564	378
Prior service (credit), net	(12)	(8)
Transition obligation, net	(2)	1
Total	550	371
Accumulated other comprehensive income expected to be recognized during the next fiscal year
Actuarial loss, net	43
Prior service cost (credit), net	(2)
Total amount expected to be recognized	41
Pension and Other Postretirement Benefit Contributions [Abstract]
Defined benefit plan contributions funded by cash flows from operations	103	118	73
Projected pension benefits payments
2012	54
2013	57
2014	60
2015	63
2016	67
2017-2021	401
Transocean Plans
Net periodic benefit costs, before tax
Service cost	64	62	62
Interest cost	80	74	67
Expected return on plan assets	(86)	(75)	(71)
Settlements and curtailments	3	8	6
Special termination benefits		(3)
Actuarial losses, net	27	17	20
Prior service cost (credit), net	(1)	(1)
Transition obligation, net		1
Net periodic benefit costs	87	89	84
Pension and Other Postretirement Benefit Contributions [Abstract]
Expected defined plan contributions in 2012	145
U.S. Plans
Net periodic benefit costs, before tax
Service cost	43	42	44
Interest cost	58	54	50
Expected return on plan assets	(63)	(58)	(55)
Settlements and curtailments	2	5	4
Special termination benefits		(3)
Actuarial losses, net	23	13	18
Prior service cost (credit), net	(1)	(1)	(1)
Net periodic benefit costs	62	58	60
Unrecognized accumulated other comprehensive income, before tax
Actuarial loss, net	447	319
Prior service (credit), net	(10)	(11)
Total	437	308
Accumulated other comprehensive income expected to be recognized during the next fiscal year
Actuarial loss, net	39
Prior service cost (credit), net	(1)
Total amount expected to be recognized	38
Projected pension benefits payments
2012	41
2013	44
2014	47
2015	50
2016	54
2017-2021	319
Non-U.S. Plans
Net periodic benefit costs, before tax
Service cost	21	20	18
Interest cost	22	20	17
Expected return on plan assets	(23)	(17)	(16)
Settlements and curtailments	1	3	2
Actuarial losses, net	4	4	2
Prior service cost (credit), net			1
Transition obligation, net		1
Net periodic benefit costs	25	31	24
Unrecognized accumulated other comprehensive income, before tax
Actuarial loss, net	113	52
Prior service (credit), net		8
Transition obligation, net	(2)	1
Total	111	61
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
2012	10
2013	10
2014	10
2015	9
2016	9
2017-2021	62
OPEB Plans
Net periodic benefit costs, before tax
Service cost	1	1
Interest cost	3	3
Net periodic benefit costs	1	2	3
Unrecognized accumulated other comprehensive income, before tax
Actuarial loss, net	4	7
Prior service (credit), net	(2)	(5)
Total	2	2
Accumulated other comprehensive income expected to be recognized during the next fiscal year
Prior service cost (credit), net	(1)
Total amount expected to be recognized	(1)
Pension and Other Postretirement Benefit Contributions [Abstract]
Expected defined plan contributions in 2012	3
Projected pension benefits payments
2012	3
2013	3
2014	3
2015	4
2016	4
2017-2021	$ 20

Postemployment Benefit Plans (Details 4) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 plan	Dec. 31, 2010	Dec. 31, 2009
Defined contribution plans
Number of defined contribution plans sponsored by the entity (in plans)	3
Contribution to plan recognized during the period
Contribution expense	$ 82	$ 69	$ 67
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			1 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Mar. 31, 2010 Gsf Explorer Capital Lease Obligation
Lease obligations
Cash payment amount terminating the capital lease obligation for GSF Explorer				$ 15
Rental expenses for all leases, including leases with terms of less than one year	169	98	99
Capital lease, future minimum rental payments
2012	66
2013	72
2014	72
2015	72
2016	73
Thereafter	918
Total future minimum rental payment	1,273
Less amount representing imputed interest	(597)
Present value of future minimum rental payments under capital leases	676
Less current portion included in debt due within one year	(17)
Long-term capital lease obligation	659
Operating leases, future minimum rental payments
2012	39
2013	39
2014	27
2015	22
2016	21
Thereafter	91
Total future minimum rental payment	239
Aggregate carrying amount of assets held under capital lease
Property and equipment, cost	742	740
Accumulated depreciation	(44)	(24)
Property and equipment, net	698	716
Depreciation expense for GSF Explorer and Petrobras 10000	$ 20	$ 23	$ 14

Commitments and Contingencies (Details 2) (New builds, USD $) In Millions, unless otherwise specified	Dec. 31, 2011
New builds
Future Purchase obligations
2012	$ 311
2013	592
2014	408
Total	$ 1,311

Commitments and Contingencies (Details 3)	1 Months Ended			12 Months Ended
Commitments and Contingencies (Details 3)	Dec. 31, 2011 USD ($) claim lawsuit subsidiary plaintiff	Dec. 31, 2011 BRL	Dec. 31, 2010 USD ($) subsidiary	Dec. 31, 2011 USD ($) lawsuit note claim subsidiary plaintiff	Dec. 21, 2011 count employee individual	Jan. 27, 2011 insurer	Dec. 15, 2010 bbl	Jun. 30, 2010 lawsuit	Apr. 22, 2010 USD ($) person mile	Sep. 30, 2006 USD ($) subsidiary	Jul. 11, 2005 subsidiary defendant landowner
Macondo well incident
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	$ 1,200,000,000		$ 135,000,000	$ 1,200,000,000
Portion of liability related to the rig explosion and fire incident recoverable from insurance	220,000,000		94,000,000	220,000,000
Percentage of non-operating interest of Anadarko in the Macondo well	25.00%	25.00%		25.00%
Percentage of non-operating interest of MOEX in the Macondo well	10.00%	10.00%		10.00%
Insurance coverage
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 self insured layer of excess liability insurance program									50,000,000
Number of actions or claims that were pending	349	349		349
Minimum number of subsidiaries entities named in numerous complaints that allege wrongful death and other personal injuries	1	1		1
Number of complaints filed 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 (in lawsuits)	34	34		34
Number of individual complaints filed alleging, among other things, economic losses as a result of environmental pollution arising out of the Macondo well incident (in lawsuits)	114	114		114
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)	184	184		184
Number of federal securities law class actions filed (in lawsuits)	2	2		2
Number of federal securities law class actions filed which generally allege violations of Section 10(b) of the Securities Exchange Act of 1934 (in counts)	1	1		1
Number of shareholder derivative suits filed (in lawsuits)								2
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 estmate of barrels of oil discharged and subject to penalties							4,100,000
Percentage of asset value covered by wreck removal insurance	25.00%	25.00%		25.00%
Asset value covered by wreck removal insurance	140,000,000			140,000,000
Amount agreed to indemnify and defend operator of rig	15,000,000			15,000,000
Notices of alleged non-compliance
Number of notices issued by the Department of the Interior's Bureau of Safety and Environmental Enforcement				4
Brazil Frade field incident
Amount sought under civil public action by a federal prosecutor in Brazilian town of Campos in Rio de Janeiro State	11,000,000,000	20,000,000,000
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
Amount excludable per occurrence, claim arising from negligence	250,000
Asbestos litigation
Number of complaints filed in 2004 in Mississippi regarding asbestos litigation (in lawsuits)	21	21		21
Number of plaintiffs covered by complaints filed in 2004 in Mississippi regarding asbestos litigation	769	769		769
Number of subsidiaries named as a direct defendant in amended asbestos complaints	1	1		1
Number of cases filed under amended complaint in Mississippi regarding asbestos litigation (in lawsuits)	7	7		7
Number of additional cases in which there may be an indirect interest regarding asbestos litigation (in lawsuits)	12	12		12
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 cases resulting in substantial verdict in favor of the plaintiff vacated on basis failure to meet burden of proof				1
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	1		1
Number of lawsuits alleging personal injury from asbestos exposure for subsidiary involved in design, construction and refurbishment of major industrial complexes	950	950		950
Estimated number of plaintiffs in lawsuits alleging personal injury from asbestos exposure for subsidiary involved in design, construction and refurbishment of major industrial complexes	2,114	2,114		2,114
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			1,000,000,000
Rio de Janeiro Tax Assessment
Tax assessment from state tax authorities of Rio de Janeiro in Brazil										187,000,000
Number of subsidiaries involved in Rio de Janeiro federal tax assessment relating to import license										1
Brazilian import license assessment
Number of subsidiaries involved in Rio de Janeiro federal tax assessment relating to import license			1
Tax assessment from federal tax authorities of Rio de Janeiro in Brazil relating to import license			235,000,000
Hazardous waste disposal sites
Percentage of liability for remediation and related costs from hazardous waste disposal site	8.00%	8.00%		8.00%
Number of subsidiaries ordered by California Regional Water Quality Control Board to develop testing plan for Alhambra, California site	1	1		1
Minimum number of subsidiaries likely to be named potentially responsible party by US Environmental Protection Agency for superfund site	1	1		1
Contamination litigation
Number of subsidiaries served with a lawsuit alleging property contamination in Louisiana											1
Number of landowners who filed a lawsuit alleging property contamination in Louisiana											3
Number of other defendants involved in lawsuit alleging property contamination in Louisiana											19
Amount claimed by plaintiffs' experts as required remediation costs for property contamination in Louisiana	300,000,000			300,000,000
Amount claimed by defendants' experts as required remediation costs for property contamination in Louisiana	2,500,000			2,500,000
Number of additional subsidiaries plaintiff attempted to add as defendant for lawsuit alleging property contamination in Louisiana	2	2		2
Amount of settlement by codefendant for property contamination in Louisiana	20,000,000			20,000,000
Number of insurers which filed pleadings to move lawsuit to United States District Court						1
Retained risk
Aggregate value of drilling rig fleet	36,400,000,000			36,400,000,000
Per occurrence insurance deductible on hull and machinery	125,000,000			125,000,000
Maximum aggregate insurance deductible on hull and machinery per year	250,000,000			250,000,000
Percentage of asset value covered by damage mitigation insurance	25.00%	25.00%		25.00%
Commercial market excess liability coverage	793,000,000			793,000,000
Excess liability coverage through wholly-owned captive insurance company	157,000,000			157,000,000
Re-insured portion of excess liability coverage through wholly-owned captive insurance company	25,000,000			25,000,000
Per occurrence deductible on crew personal injury liability and collision liability claims	10,000,000			10,000,000
Per occurrence deductible on other third-party non-crew claims	5,000,000			5,000,000
Aggregate per occurrence deductible on other third party non-crew claims	50,000,000			50,000,000
Liability loss limit for commercial market excess liability coverage	1,000,000,000			1,000,000,000
Additional insurance that covers expenses that would otherwise be assumed by the well owner	100,000,000			100,000,000
Maximum liability amount for well control and re-drilling liability related to blowouts	50,000,000			50,000,000
Letters of credit and surety bonds
Letters of credit outstanding	650,000,000		595,000,000	650,000,000
Amount of letter of credit issued on behalf of TPDI	60,000,000		60,000,000	60,000,000
Number of subsidiaries that established the letter of credit on behalf of TPDI	1	1		1
Surety bonds outstanding	$ 12,000,000		$ 27,000,000	$ 12,000,000

Redeemable Noncontrolling Interest (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010
Redeemable Noncontrolling Interest
Percentage interest in joint venture (TPDI) that is held by an unaffiliated party (Quantum)	50.00%
Redeemable noncontrolling interest
Balance, beginning of period	$ 25
Reclassification from noncontrolling interest		26
Net income attributable to noncontrolling interest	94	13
Other comprehensive loss attributable to noncontrolling interest	(3)	(14)
Balance, end of period	$ 116	$ 25

Shareholders' Equity (Details)	1 Months Ended				12 Months Ended
Shareholders' Equity (Details)	Dec. 31, 2011 USD ($)	Dec. 31, 2011 CHF	May 31, 2009 CHF	Dec. 31, 2008 subsidiary	Dec. 31, 2011 USD ($) installment	Dec. 31, 2010 USD ($)	Dec. 31, 2010 CHF	May 31, 2011 USD ($) installment
Share issuance
Issuance of shares (in shares)	29,900,000	29,900,000		16,000,000
Price per share issued under public offering	$ 40.50	37.19
Share repurchase USD exchange rate	$ 1				$ 1
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	1,211,000,000				1,211,000,000
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 quarterly installments paid					3
Installment of dividend paid					763,000,000
Unpaid distribution payable	278,000,000				278,000,000
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	29,900,000	29,900,000		16,000,000
Number of subsidiaries to whom shares were issued				1
Number of shares held by subsidiary	12,000,000	12,000,000			12,000,000	13,000,000	13,000,000
Share repurchase program
Authorized amount for repurchase of shares			3,500,000,000		3,700,000,000
Share repurchase USD exchange rate	1				1
Share repurchase CHF exchange rate		0.94
Treasury shares purchased under share repurchase program						2,863,267	2,863,267
Aggregate purchase price						$ 240,000,000	257,000,000
Treasury shares	2,863,267	2,863,267			2,863,267	2,863,267	2,863,267

Share-Based Compensation Plans (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 Y	Dec. 31, 2010	Dec. 31, 2009
Share Based Compensation Plans
Shares authorized under the plan	36,000,000
Shares available for grant under the plan	15,000,000
Total unrecognized compensation costs related to all unvested share based awards	$ 91
Weighted average period over compensation costs are expected to be recognized (in years)	1.8
Additional share based compensation expense in connection with modification of share-based awards	3	12	8
Stock options
Share Based Compensation Plans
General term of awards after they are vested	P10Y
Option valuation assumptions
Dividend yield (as a percent)	4.00%	4.00%
Expected price volatility (as a percent)	40.00%	39.00%	49.00%
Risk free interest rate (as a percent)	1.97%	2.30%	1.80%
Expected life of options (in years)	4.9	4.7	4.8
Granted (in dollars per share)	$ 19.75	$ 30.03	$ 26.07
Weighted-average grant-date fair value per share
Granted (in dollars per share)	$ 19.75	$ 30.03	$ 26.07
SARs
Share Based Compensation Plans
General term of awards after they are vested	P10Y
Time-Based Awards
Share Based Compensation Plans
Vesting period (in years)	3 years
Time-Based Awards \| Stock options
Option valuation assumptions
Granted (in dollars per share)	$ 19.75	$ 30.03	$ 26.07
Stock option activity
Outstanding at the beginning of the period (in shares)	1,653,683
Granted (in shares)	194,342	253,288	597,898
Exercised (in shares)	(210,997)	(289,445)	(980,105)
Forfeited (in shares)	(47,515)
Expired (in shares)	(10,229)
Outstanding at the end of the period (in shares)	1,579,284	1,653,683
Vested and exercisable at the end of the period (in shares)	1,182,287
Weighted-average exercise price per share
Outstanding at the beginning of the period (in dollars per share)	$ 66.37
Granted (in dollars per share)	$ 78.76
Exercised (in dollars per share)	$ 46.37
Forfeited (in dollars per share)	$ 84.77
Expired (in dollars per share)	$ 42.79
Outstanding at the end of the period (in dollars per share)	$ 70.16	$ 66.37
Vested and exercisable at the end of the period (in dollars per share)	$ 68.13
Weighted-average remaining contractual term (years)
Outstanding at the beginning of the period (in years)	5.29
Outstanding at the end of the period (in years)	2.67	5.29
Vested and exercisable at the end of the period (in years)	2.67
Aggregate intrinsic value (in millions)
Outstanding at the beginning of the period	5
Outstanding at the end of the period	0	5
Exercised during the period	5	11	43
Additional disclosure
Unvested options outstanding (in shares)	396,997	470,400	656,790
Weighted-average grant-date fair value per share
Granted (in dollars per share)	$ 19.75	$ 30.03	$ 26.07
Time-Based Awards \| Restricted shares
Equity instruments other than options activity
Outstanding at the beginning of the period (in shares)	3,939
Vested (in shares)	(3,939)	(92,573)	(320,782)
Outstanding at the end of the period (in shares)	0	3,939
Weighted-average grant-date fair value per share
Outstanding at the beginning of the period (in dollars per share)	$ 132.32
Vested (in dollars per share)	$ 132.32
Outstanding at the end of the period (in dollars per share)		$ 132.32
Additional disclosure
Total grant date fair value	1	10	39
Time-Based Awards \| Deferred units
Equity instruments other than options activity
Outstanding at the beginning of the period (in shares)	1,844,784
Granted (in shares)	1,090,747	1,055,367	1,287,893
Vested (in shares)	(832,252)	(559,339)	(282,543)
Forfeited (in shares)	(163,439)
Outstanding at the end of the period (in shares)	1,939,840	1,844,784
Weighted-average grant-date fair value per share
Outstanding at the beginning of the period (in dollars per share)	$ 75.23
Granted (in dollars per share)	$ 77.55	$ 76.83	$ 60.53
Vested (in dollars per share)	$ 78.97
Forfeited (in dollars per share)	$ 76.94
Outstanding at the end of the period (in dollars per share)	$ 74.78	$ 75.23
Additional disclosure
Total grant date fair value	$ 66	$ 45	$ 33
Time-Based Awards \| SARs
Equity instruments other than options activity
Outstanding at the beginning of the period (in shares)	189,139
Exercised (in shares)	(1,400)
Forfeited (in shares)	(7,768)
Outstanding at the end of the period (in shares)	179,971	189,139
Vested and exercisable at the end of the period (in shares)	179,971
Weighted average exercise price per share
Outstanding at the beginning of the period (in dollars per share)	$ 93.28	$ 93.28
Exercised (in dollars per share)	$ 77.73
Forfeited (in dollars per share)	$ 105.57
Outstanding at the end of the period (in dollars per share)	$ 93.28	$ 93.28
Vested and exercisable at the end of the period (in dollars per share)	$ 92.87
Weighted-average remaining contractual term (years)
Weighted-average remaining contractual term, at the end of the period (in years)	4.66	5.76
Vested and exercisable, at the end of the period (in years)	4.66
Additional disclosure
Exercises (in shares)			224
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
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
Vested and exercisable at the end of the period (in dollars per share)	$ 75.30
Weighted-average remaining contractual term (years)
Outstanding at the beginning of the period (in years)	5.22
Outstanding at the end of the period (in years)	4.23
Vested and exercisable at the end of the period (in years)	4.23
Two-year Awards
Share Based Compensation Plans
Measurement period, (in years)	2
Number of equal installments vesting	3
Number of years subsequent to first installment	2
Three-year Awards
Share Based Compensation Plans
Measurement period, (in years)	3
Number of equal installments vesting	1
Market-Based Awards \| Deferred units
Equity instruments other than options activity
Outstanding at the beginning of the period (in shares)	422,906
Granted (in shares)	98,797	122,934	285,012
Forfeited (in shares)	(105,756)
Outstanding at the end of the period (in shares)	415,947	422,906
Weighted-average grant-date fair value per share
Outstanding at the beginning of the period (in dollars per share)	$ 89.14
Granted (in dollars per share)	$ 78.69	$ 82.55	$ 75.98
Forfeited (in dollars per share)	$ 121.89
Outstanding at the end of the period (in dollars per share)	$ 75.98	$ 89.14

Supplemental Balance Sheet Information (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Other current liabilities
Accrued payroll and employee benefits	$ 340	$ 270
Distribution payable	278
Deferred revenue	181	134
Deferred revenue of consolidated variable interest entities	16	16
Accrued taxes, other than income	127	126
Accrued interest	132	97
Unearned income	2	15
Contingent liabilities	1,229	164
Other	45	61
Total other current liabilities	2,350	883
Other long-term liabilities
Long-term income taxes payable	729	675
Accrued pension liabilities	579	426
Deferred revenue	244	302
Deferred revenue of consolidated variable interest entities	85	91
Drilling contract intangibles	103	152
Accrued retiree life insurance and medical benefits	49	52
Other	114	93
Total other long-term liabilities	$ 1,903	$ 1,791

Supplemental Cash Flow Information (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended			1 Months Ended	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010 drillingunit	Dec. 31, 2009	Aug. 31, 2009 Petrobras 10000	Dec. 31, 2010 Midwater Floaters drillingunit note
Changes in operating assets and liabilities
Decrease (increase) in accounts receivable	$ (174)	$ 386	$ 504
Increase in other current assets	(73)	(75)	(50)
Increase in other assets	(5)	(40)	(30)
Increase (decrease) in accounts payable and other current liabilities	978	227	(60)
Decrease in other long-term liabilities	(34)	(52)	(7)
Change in income taxes receivable / payable, net	53	(37)	77
Net cash provided by (used in) operating activities	745	409	434
Certain cash operating activities
Cash payments for interest	626	641	683
Cash payments for income taxes	338	493	663
Non-cash investing and financing activities
Capital expenditures, accrued at end of period	68	69	139
Asset capitalized under capital leases			716
Non-cash proceeds received for the sale of assets		134
Significant Acquisitions and Disposals
Non-cash additions to property and equipment				716
Number of Midwater Floaters sold (in drilling units)		2			2
Net cash proceeds from sale of assets	177	60	18		38
Number of Notes Receivable Noncash, Proceeds from Sale of Assets					2
Non-cash proceeds in the form of notes receivable from sale of assets					$ 165

Fair Value of Financial Instruments (Details) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Financial instruments
Restricted cash investments	$ 928	$ 47
TPDI and ADDCL Credit Facilities
Financial instruments
Restricted cash investments	39	39
Aker Drilling
Financial instruments
Restricted cash investments	889
Carrying amount
Financial instruments
Cash and cash equivalents	4,017	3,394
Accounts receivable	2,049	1,653
Notes receivable and working capital loan receivable	139	115
Restricted cash investments	928	47
Long-term debt, including current maturities	12,698	10,271
Long-term debt of consolidated variable interest entities, including current maturities	838	950
Derivative instruments, assets	36	21
Derivative instruments, liabilities	38	13
Notes receivable and working capital loan receivable
Notes receivable, current	37	4
Notes receivable, noncurrent	102	111
Fair value
Financial instruments
Cash and cash equivalents	4,017	3,394
Accounts receivable	2,049	1,653
Notes receivable and working capital loan receivable	139	115
Restricted cash investments	975	47
Long-term debt, including current maturities	13,074	10,562
Long-term debt of consolidated variable interest entities, including current maturities	838	964
Derivative instruments, assets	36	21
Derivative instruments, liabilities	$ 38	$ 13

Financial Instruments and Risk Concentration (Details)	12 Months Ended
Financial Instruments and Risk Concentration (Details)	Dec. 31, 2011 Y employee
Interest rate risk
Maturity period of debt for exposure to changes in market interest rates, minimum (in years)	1
Labour Agreements
Number of employees	18,700
Number of employees engaged through contract labor providers	1,850

Variable Interest Entities (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 note	Dec. 31, 2010 note drillingunit
Carrying amounts associated with consolidated variable interest entities
Assets	$ 2,492	$ 2,462
Liabilities	1,007	1,108
Net carrying amount	1,485	1,354
Aggregate carrying amount of consolidated VIEs assets, pledged as security against outstanding debt of consolidated VIEs	2,165	2,191
Unconsolidated Variable interest entities
Number of notes receivable from sale of Midwater Floaters	2	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%	9.00%
Stated interest rate on working capital loan (as a percent)	10.00%	10.00%
Maximum borrowing amount of working capital loan in connection with sale of Midwater Floaters	35	35
Aggregate carrying amounts of notes receivable in connection with sale of Midwater Floaters	110	109
Aggregate carrying amounts of working capital loan receivable in connection with sale of Midwater Floaters	29	6
TPDI
Carrying amounts associated with consolidated variable interest entities
Assets	1,562	1,598
Liabilities	673	763
Net carrying amount	889	835
ADDCL
Carrying amounts associated with consolidated variable interest entities
Assets	930	864
Liabilities	334	345
Net carrying amount	$ 596	$ 519

Related Party Transactions (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	12 Months Ended			12 Months Ended
	Dec. 31, 2009	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2011 Overseas Drilling Limited	Dec. 31, 2010 Overseas Drilling Limited	Dec. 31, 2011 TPDI	Dec. 31, 2010 TPDI	Dec. 31, 2011 ADDCL	Dec. 31, 2011 Quantum Pacific Management Limited TPDI	Dec. 31, 2010 Quantum Pacific Management Limited TPDI	Dec. 31, 2011 Angco Cayman Limited ADDCL	Dec. 31, 2011 Siem Offshore Inc Overseas Drilling Limited
Related Party Transactions
Ownership interest in affiliate (as a percent)						50.00%		65.00%
Outstanding promissory notes						$ 296	$ 296
Outstanding promissory notes due to related party		13,536	11,221						148	148
Noncontrolling owner's ownership interest in affiliate (as a percent)		50.00%				50.00%		35.00%			35.00%	50.00%
Earning from operational and management services				1	2
Ownership interest in unconsolidated joint venture (as a percent)				50.00%
Proceeds from sale of unconsolidated affiliates				22
Gain on sale of unconsolidated affiliates	$ 30			$ 13
Gain on sale of unconsolidated affiliates per diluted share	$ 0.09			$ 0.04

Operating Segments, Geographic Analysis and Major Customers (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 segment	Dec. 31, 2010	Dec. 31, 2009
Operating Segments, Geographic Analysis and Major Customers
Number of operating segments	2
Segments, Geographical Analysis and Major Customers
Operating revenues	$ 9,142	$ 9,466	$ 11,441
U.S.
Segments, Geographical Analysis and Major Customers
Operating revenues	1,975	2,087	2,209
U.K.
Segments, Geographical Analysis and Major Customers
Operating revenues	1,211	1,183	1,563
Brazil
Segments, Geographical Analysis and Major Customers
Operating revenues	1,019	1,288	1,108
Other countries
Segments, Geographical Analysis and Major Customers
Operating revenues	$ 4,937	$ 4,908	$ 6,561
Threshold of operating revenues for reporting individually as a country (as a percent)	10.00%

Operating Segments, Geographic Analysis and Major Customers (Details 2) (USD $) In Millions, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Segments, Geographical Analysis and Major Customers
Long-lived assets	$ 22,529	$ 21,319
Long-lived assets in Switzerland	8	15
U.S.
Segments, Geographical Analysis and Major Customers
Long-lived assets	6,549	5,519
Brazil
Segments, Geographical Analysis and Major Customers
Long-lived assets	2,185	2,472
India
Segments, Geographical Analysis and Major Customers
Long-lived assets	1,593	2,632
Other countries
Segments, Geographical Analysis and Major Customers
Long-lived assets	$ 12,202	$ 10,696
Threshold for long lived assets for reporting individually as a country (as a percent)	10.00%

Condensed Consolidating Financial Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Condensed Consolidating Financial Information
Operating revenues	$ 2,422	$ 2,242	$ 2,334	$ 2,144	$ 2,127	$ 2,281	$ 2,479	$ 2,579	$ 9,142	$ 9,466	$ 11,441
Cost and expenses									8,693	6,856	6,708
Loss on impairment					(1,000)				(5,229)	(1,010)	(334)
Gain on disposal of assets, net									4	257	(9)
Operating income (loss)	(5,807)	268	391	372	(668)	634	949	942	(4,776)	1,857	4,390
Other income (expense), net
Interest income (expense), net									(577)	(544)	(479)
Equity in earnings									18	8	6
Other, Net									(99)	(31)	2
Total other income (expense), net									(658)	(567)	(471)
Loss from continuing operations before income tax expense									(5,434)	1,290	3,919
Income tax expense									395	336	723
Loss from continuing operations	(6,102)	(53)	162	164	(804)	363	712	683	(5,829)	954	3,196
Income (loss) from discontinued operations, net of tax									197	34	(26)
Net income (loss)									(5,632)	988	3,170
Net income attributable to noncontrolling interest									93	27	(11)
Net income (loss) attributable to controlling interest	(6,119)	(71)	155	310	(799)	368	715	677	(5,725)	961	3,181
Five Year Revolving Credit Facility
Other income (expense), net
Term of revolving credit facility									5 years
Parent Guarantor
Condensed Consolidating Financial Information
Cost and expenses									44	45	26
Operating income (loss)									(44)	(45)	(26)
Other income (expense), net
Interest income (expense), net									(11)	1	1
Equity in earnings									(5,670)	1,005	3,206
Total other income (expense), net									(5,681)	1,006	3,207
Loss from continuing operations before income tax expense									(5,725)	961	3,181
Loss from continuing operations									(5,725)	961	3,181
Net income (loss)									(5,725)	961	3,181
Net income (loss) attributable to controlling interest									(5,725)	961	3,181
Subsidiary Issuer
Condensed Consolidating Financial Information
Cost and expenses									4	3	4
Operating income (loss)									(4)	(3)	(4)
Other income (expense), net
Interest income (expense), net									(510)	(494)	(521)
Equity in earnings									(5,145)	1,519	3,773
Other, Net									9	(7)	(43)
Total other income (expense), net									(5,646)	1,018	3,209
Loss from continuing operations before income tax expense									(5,650)	1,015	3,205
Loss from continuing operations									(5,650)	1,015	3,205
Net income (loss)									(5,650)	1,015	3,205
Net income (loss) attributable to controlling interest									(5,650)	1,015	3,205
Other Subsidiaries
Condensed Consolidating Financial Information
Operating revenues									9,160	9,481	11,455
Cost and expenses									8,663	6,823	6,692
Loss on impairment									(5,229)	(1,010)	(334)
Gain on disposal of assets, net									4	257	(9)
Operating income (loss)									(4,728)	1,905	4,420
Other income (expense), net
Interest income (expense), net									(56)	(51)	41
Equity in earnings									18	8	6
Other, Net									(108)	(24)	45
Total other income (expense), net									(146)	(67)	92
Loss from continuing operations before income tax expense									(4,874)	1,838	4,512
Income tax expense									395	336	723
Loss from continuing operations									(5,269)	1,502	3,789
Income (loss) from discontinued operations, net of tax									197	34	(26)
Net income (loss)									(5,072)	1,536	3,763
Net income attributable to noncontrolling interest									93	27	(11)
Net income (loss) attributable to controlling interest									(5,165)	1,509	3,774
Consolidating adjustments
Condensed Consolidating Financial Information
Operating revenues									(18)	(15)	(14)
Cost and expenses									(18)	(15)	(14)
Other income (expense), net
Equity in earnings									10,815	(2,524)	(6,979)
Total other income (expense), net									10,815	(2,524)	(6,979)
Loss from continuing operations before income tax expense									10,815	(2,524)	(6,979)
Loss from continuing operations									10,815	(2,524)	(6,979)
Net income (loss)									10,815	(2,524)	(6,979)
Net income (loss) attributable to controlling interest									$ 10,815	$ (2,524)	$ (6,979)

Condensed Consolidating Financial Information (Details 2) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Assets
Cash and cash equivalents	$ 4,017	$ 3,394	$ 1,130	$ 963
Other current assets	3,592	2,801
Total current assets	7,609	6,195
Property and equipment, net	22,529	21,319
Goodwill	3,205	8,132
Investment in affiliates		19
Other assets	1,745	1,146
Total assets	35,088	36,811
Liabilities and equity
Debt due within one year	2,039	2,012
Other current liabilities	3,319	1,824
Total current liabilities	5,358	3,836
Long-term debt	11,497	9,209
Other long-term liabilities	2,426	2,366
Total long-term liabilities	13,923	11,575
Commitments and contingencies
Redeemable noncontrolling interest	116	25
Total equity	15,691	21,375	20,559	17,167
Total liabilities and equity	35,088	36,811
Parent Guarantor
Assets
Cash and cash equivalents	3	38	5
Other current assets	8	12
Total current assets	11	50
Property and equipment, net	1	1
Investment in affiliates	16,503	21,373
Total assets	16,515	21,424
Liabilities and equity
Other current liabilities	294	21
Total current liabilities	294	21
Long-term debt	495
Other long-term liabilities	25	20
Total long-term liabilities	520	20
Commitments and contingencies
Total equity	15,701	21,383
Total liabilities and equity	16,515	21,424
Subsidiary Issuer
Assets
Cash and cash equivalents	2,793	2,041	117	114
Other current assets	784	788
Total current assets	3,577	2,829
Investment in affiliates	27,582	33,473
Other assets	1,368	1,017
Total assets	32,527	37,319
Liabilities and equity
Debt due within one year	1,693	1,891
Other current liabilities	367	444
Total current liabilities	2,060	2,335
Long-term debt	14,308	13,354
Other long-term liabilities	439	292
Total long-term liabilities	14,747	13,646
Commitments and contingencies
Total equity	15,720	21,338
Total liabilities and equity	32,527	37,319
Other Subsidiaries
Assets
Cash and cash equivalents	1,221	1,315	1,008	849
Other current assets	4,493	3,189
Total current assets	5,714	4,504
Property and equipment, net	22,528	21,318
Goodwill	3,205	8,132
Investment in affiliates		19
Other assets	17,908	14,001
Total assets	49,355	47,974
Liabilities and equity
Debt due within one year	346	121
Other current liabilities	4,351	2,547
Total current liabilities	4,697	2,668
Long-term debt	14,225	9,727
Other long-term liabilities	1,962	2,054
Total long-term liabilities	16,187	11,781
Commitments and contingencies
Redeemable noncontrolling interest	116	25
Total equity	28,355	33,500
Total liabilities and equity	49,355	47,974
Consolidating adjustments
Assets
Other current assets	(1,693)	(1,188)
Total current assets	(1,693)	(1,188)
Investment in affiliates	(44,085)	(54,846)
Other assets	(17,531)	(13,872)
Total assets	(63,309)	(69,906)
Liabilities and equity
Other current liabilities	(1,693)	(1,188)
Total current liabilities	(1,693)	(1,188)
Long-term debt	(17,531)	(13,872)
Total long-term liabilities	(17,531)	(13,872)
Commitments and contingencies
Total equity	(44,085)	(54,846)
Total liabilities and equity	$ (63,309)	$ (69,906)

Condensed Consolidating Financial Information (Details 3) (USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Condensed Consolidating Financial Information
Cash flows from operating activities		$ 1,785	$ 3,946	$ 5,598
Cash flows from investing activities
Capital expenditures		(1,020)	(1,391)	(3,041)
Investment in business combination, net of cash acquired		(1,246)
Proceeds from disposal of assets, net		177	60	18
Proceeds from disposal of discontinued operations, net		284
Proceeds from insurance recoveries for loss of drilling unit			560
Other, net		(91)	50	347
Net cash used in investing activities		(1,896)	(721)	(2,694)
Cash flows from financing activities
Changes in short-term borrowings, net		(88)	(193)	(382)
Proceeds from debt		2,939	2,054	514
Repayments of debt		(2,409)	(2,565)	(2,871)
Proceeds from share issuance, net	1,211	1,211
Distribution of qualifying additional paid-in capital		(763)
Purchases of shares held in treasury			(240)
Other, net		(156)	(17)	2
Net cash provided by (used in) financing activities		734	(961)	(2,737)
Net increase in cash and cash equivalents		623	2,264	167
Cash and cash equivalents at beginning of period		3,394	1,130	963
Cash and cash equivalents at end of period	4,017	4,017	3,394	1,130
Parent Guarantor
Condensed Consolidating Financial Information
Cash flows from operating activities		(52)	(33)	(24)
Cash flows from investing activities
Capital expenditures			(4)	(1)
Investing activities with affiliates, net		(875)	310	29
Net cash used in investing activities		(875)	306	28
Cash flows from financing activities
Proceeds from debt		435
Repayments of debt		(429)
Proceeds from share issuance, net		1,211
Distribution of qualifying additional paid-in capital		(763)
Financing activities with affiliates, net		495
Purchases of shares held in treasury			(240)
Other, net		(57)		1
Net cash provided by (used in) financing activities		892	(240)	1
Net increase in cash and cash equivalents		(35)	33	5
Cash and cash equivalents at beginning of period		38	5
Cash and cash equivalents at end of period	3	3	38	5
Subsidiary Issuer
Condensed Consolidating Financial Information
Cash flows from operating activities		503	(358)	(429)
Cash flows from investing activities
Investing activities with affiliates, net		(325)	1,357	1,667
Other, net		(23)	(6)
Net cash used in investing activities		(348)	1,351	1,667
Cash flows from financing activities
Changes in short-term borrowings, net		(88)	(193)	(382)
Proceeds from debt		2,504	1,999
Repayments of debt		(1,827)	(2,245)	(2,865)
Financing activities with affiliates, net		43	1,384	2,008
Other, net		(35)	(14)	4
Net cash provided by (used in) financing activities		597	931	(1,235)
Net increase in cash and cash equivalents		752	1,924	3
Cash and cash equivalents at beginning of period		2,041	117	114
Cash and cash equivalents at end of period	2,793	2,793	2,041	117
Other Subsidiaries
Condensed Consolidating Financial Information
Cash flows from operating activities		1,334	4,337	6,051
Cash flows from investing activities
Capital expenditures		(1,020)	(1,387)	(3,040)
Investment in business combination, net of cash acquired		(1,246)
Proceeds from disposal of assets, net		177	60
Proceeds from disposal of discontinued operations, net		284
Investing activities with affiliates, net		(693)	(1,694)	(2,068)
Proceeds from insurance recoveries for loss of drilling unit			560
Other, net		(68)	56	347
Net cash used in investing activities		(2,566)	(2,405)	(4,761)
Cash flows from financing activities
Proceeds from debt			55	514
Repayments of debt		(153)	(320)	(6)
Financing activities with affiliates, net		1,355	(1,357)	(1,636)
Other, net		(64)	(3)	(3)
Net cash provided by (used in) financing activities		1,138	(1,625)	(1,131)
Net increase in cash and cash equivalents		(94)	307	159
Cash and cash equivalents at beginning of period		1,315	1,008	849
Cash and cash equivalents at end of period	1,221	1,221	1,315	1,008
Consolidating adjustments
Cash flows from investing activities
Investing activities with affiliates, net		1,893	27	372
Net cash used in investing activities		1,893	27	372
Cash flows from financing activities
Financing activities with affiliates, net		(1,893)	(27)	(372)
Net cash provided by (used in) financing activities		$ (1,893)	$ (27)	$ (372)

Quarterly Results (Unaudited) (Details) (USD $) Share data in Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Quarterly Results (Unaudited)
Operating revenues	$ 2,422,000,000	$ 2,242,000,000	$ 2,334,000,000	$ 2,144,000,000	$ 2,127,000,000	$ 2,281,000,000	$ 2,479,000,000	$ 2,579,000,000	$ 9,142,000,000	$ 9,466,000,000	$ 11,441,000,000
Operating income (loss)	(5,807,000,000)	268,000,000	391,000,000	372,000,000	(668,000,000)	634,000,000	949,000,000	942,000,000	(4,776,000,000)	1,857,000,000	4,390,000,000
Income (loss) from continuing operations	(6,102,000,000)	(53,000,000)	162,000,000	164,000,000	(804,000,000)	363,000,000	712,000,000	683,000,000	(5,829,000,000)	954,000,000	3,196,000,000
Net income (loss) attributable to controlling interest	(6,119,000,000)	(71,000,000)	155,000,000	310,000,000	(799,000,000)	368,000,000	715,000,000	677,000,000	(5,725,000,000)	961,000,000	3,181,000,000
Earnings (loss) per share
Basic (in dollars per share)	$ (18.70)	$ (0.20)	$ 0.47	$ 0.42	$ (2.53)	$ 1.10	$ 2.20	$ 2.09	$ (17.79)	$ 2.99	$ 9.87
Diluted (in dollars per share)	$ (18.70)	$ (0.20)	$ 0.47	$ 0.42	$ (2.53)	$ 1.10	$ 2.20	$ 2.08	$ (17.79)	$ 2.99	$ 9.84
Weighted-average shares outstanding
Basic: (in shares)	329	320	320	319	319	319	319	321	322	320	320
Diluted: (in shares)	329	320	320	320	319	319	320	322	322	320	321
Gain on the loss of Deepwater Horizon							267,000,000			267,000,000
Loss on impairment					1,000,000,000				5,229,000,000	1,010,000,000	334,000,000
Impairment	5,200,000,000								5,200,000,000
Loss recognized during the period		78,000,000
Loss associated with the Macondo well incident contingencies	1,000,000,000
Gains (losses) on disposal of discontinued operations	$ 12,000,000	$ (4,000,000)		$ 173,000,000					$ 181,000,000

Subsequent Events (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended		1 Months Ended		1 Months Ended
	Dec. 31, 2011 employee subsidiary	Dec. 31, 2011 1.50% Series B Convertible Senior Notes due December 2037	Jan. 31, 2012 Debt 1.50% Series B Convertible Senior Notes due December 2037	Jan. 31, 2012 Drilling fleet Standard Jackups, GSF Rig 136, Transocean Nordic, and Shelf Explorer	Jan. 31, 2012 Tax investigations subsidiary employee
Subsequent Events
Redemption of debt		$ 1,700	$ 30
Carrying value of drilling fleet assets reclassified to assets held for sale				59
Net adjustments of additional taxes, excluding interest, related to assessments on 2008 and 2009 U.S. federal income tax returns					473
Financial claim issued by the Norwegian authorities supplementing the criminal indictments					$ 315
Number of subsidiaries against which notification of criminal charges are issued	2				2
Number of employees of former external advisors indicted	2				2

Schedule II - Valuation and Qualifying Accounts (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Allowance for doubtful accounts receivable
Reserves and allowances deducted from asset accounts
Balance at the beginning of the period	$ 38	$ 65	$ 114
Charge to cost and expenses		5	27
Deductions	10	32	76
Balance at the end of the period	28	38	65
Allowance for obsolete materials and supplies
Reserves and allowances deducted from asset accounts
Balance at the beginning of the period	70	66	49
Charge to cost and expenses	5	6	17
Deductions	2	2
Balance at the end of the period	73	70	66
Deductions resulting from sale of rigs and inventory		1
Deductions resulting from loss of Deepwater Horizon		1
Valuation allowance on deferred tax assets
Reserves and allowances deducted from asset accounts
Balance at the beginning of the period	164	160	111
Charge to cost and expenses	19	8	49
Deductions		4
Balance at the end of the period	$ 183	$ 164	$ 160

Nature of Business (Details 2)	1 Months Ended	12 Months Ended
Nature of Business (Details 2)	Oct. 31, 2011 drillingunit	Dec. 31, 2011 drillingunit
Business Combination
Number of Ultra-Deepwater Floaters under construction (in drilling units)	2	2
Aker Drilling
Business Combination
Number of Harsh Environment, ultra-deepwater, semi-submersibles operated by an acquired entity (in drilling units)	2	2
Number of Ultra-Deepwater Floaters under construction (in drilling units)	2	2

Drilling Fleet (Details 2)	Dec. 31, 2011
Schedule of Variable Interest Entities
Noncontrolling owner's ownership interest in affiliate (as a percent)	50.00%
TPDI
Schedule of Variable Interest Entities
Ownership interest in affiliate (as a percent)	50.00%
Noncontrolling owner's ownership interest in affiliate (as a percent)	50.00%
ADDCL
Schedule of Variable Interest Entities
Ownership interest in affiliate (as a percent)	65.00%
Noncontrolling owner's ownership interest in affiliate (as a percent)	35.00%

Operating Segments, Geographic Analysis and Major Customers (Details 3) (Total operating revenues, Operating revenues, BP)	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Total operating revenues \| Operating revenues \| BP
Concentration Risk
Percentage of concentration	10.00%	10.00%	12.00%