Document And Entity Information (USD $) In Billions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2011	Apr. 26, 2011	Jun. 30, 2010
Entity Registrant Name	Transocean Ltd.
Entity Central Index Key	0001451505
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			$ 14.8
Entity Common Stock, Shares Outstanding		319,567,451
Document Fiscal Year Focus	2011
Document Fiscal Period Focus	Q1
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2011

CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2011	Mar. 31, 2010
Operating revenues
Contract drilling revenues	$ 1,950	$ 2,425
Contract drilling intangible revenues	10	33
Other revenues	184	121
Total operating revenues	2,144	2,579
Costs and expenses
Operating and maintenance	1,359	1,186
Depreciation and amortization	354	374
General and administrative	67	63
Costs and expenses	1,780	1,623
Gain (loss) on disposal of assets, net	8	(14)
Operating income	372	942
Other income (expense), net
Interest income	15	5
Interest expense, net of amounts capitalized	(145)	(132)
Other, net	3	15
Total other income (expense), net	(127)	(112)
Income from continuing operations before income tax expense	245	830
Income tax expense	81	147
Income from continuing operations	164	683
Income from discontinued operations, net of tax	176	2
Net income	340	685
Net income attributable to noncontrolling interest	30	8
Net income attributable to controlling interest	$ 310	$ 677
Earnings per share-basic
Earnings from continuing operations, basic	$ 0.42	$ 2.09
Earnings from discontinued operations, basic	$ 0.54	$ 0.01
Earnings per share	$ 0.96	$ 2.10
Earnings per share-diluted
Earnings from continuing operations, diluted	$ 0.42	$ 2.08
Earnings from discontinued operations, diluted	$ 0.54	$ 0.01
Earnings per share	$ 0.96	$ 2.09
Weighted - average shares outstanding
Basic (in shares)	319	321
Diluted (in shares)	320	322

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2011	Mar. 31, 2010
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) [Abstract]
Net income	$ 340	$ 685
Other comprehensive income (loss) before income taxes
Unrecognized components of net periodic benefit costs	(6)	(10)
Recognized components of net periodic benefit costs	6	6
Unrecognized gain (loss) on derivative instruments	1	(10)
Recognized loss on derivative instruments	2	4
Other comprehensive income (loss) before income taxes	3	(10)
Income taxes related to other comprehensive income (loss)	(2)	0
Other comprehensive income (loss), net of income taxes	1	(10)
Total comprehensive income	341	675
Total comprehensive income (loss) attributable to noncontrolling interest	34	1
Total comprehensive income attributable to controlling interest	$ 307	$ 674

CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2011	Dec. 31, 2010
Assets
Cash and cash equivalents	$ 3,812	$ 3,394
Accounts receivable, net of allowance for doubtful accounts of $33 and $38 at March 31, 2011 and December 31, 2010, respectively	2,161	1,978
Materials and supplies, net of allowance for obsolescence of $70 at March 31, 2011 and December 31, 2010	541	514
Deferred income taxes, net	116	115
Assets held for sale	77	0
Other current assets	197	194
Total current assets	6,904	6,195
Property and equipment	26,819	26,721
Property and equipment of consolidated variable interest entities	2,241	2,214
Less accumulated depreciation	7,887	7,616
Property and equipment, net	21,173	21,319
Goodwill	8,132	8,132
Other assets	1,001	1,165
Total assets	37,210	36,811
Liabilities and equity
Accounts payable	808	832
Accrued income taxes	67	109
Debt due within one year	1,965	1,917
Debt of consolidated variable interest entities due within one year	95	95
Other current liabilities	906	883
Total current liabilities	3,841	3,836
Long - term debt	8,361	8,354
Long - term debt of consolidated variable interest entities	820	855
Deferred income taxes, net	586	575
Other long - term liabilities	1,840	1,791
Total long - term liabilities	11,607	11,575
Commitments and contingencies
Redeemable noncontrolling interest	57	25
Shares, CHF 15.00 par value, 335,235,298 authorized, 167,617,649 conditionally authorized, 335,235,298 issued at March 31, 2011 and December 31, 2010; 319,538,901 and 319,080,678 outstanding at March 31, 2011 and December 31, 2010, respectively	4,488	4,482
Additional paid - in capital	7,518	7,504
Treasury shares, at cost, 2,863,267 held at March 31, 2011 and December 31, 2010	(240)	(240)
Retained earnings	10,279	9,969
Accumulated other comprehensive loss	(335)	(332)
Total controlling interest shareholders' equity	21,710	21,383
Noncontrolling interest	(5)	(8)
Total equity	21,705	21,375
Total liabilities and equity	$ 37,210	$ 36,811

CONDENSED CONSOLIDATED BALANCE SHEETS Parenthetical In Millions, except Share data, unless otherwise specified	Mar. 31, 2011 USD ($)	Mar. 31, 2011 CHF	Dec. 31, 2010 USD ($)	Dec. 31, 2010 CHF
Assets
Accounts receivable, net of allowance for doubtful accounts	$ 33		$ 38
Materials and supplies, net of allowance for obsolescence	$ 70		$ 70
Liabilities and equity
Shares, CHF par value (in Swiss Francs per share)		15.00		15.00
Shares, authorized (in shares)	335,235,298	335,235,298	335,235,298	335,235,298
Shares, conditionally authorized (in shares)	167,617,649	167,617,649	167,617,649	167,617,649
Shares issued (in shares)	335,235,298	335,235,298	335,235,298	335,235,298
Shares outstanding (in shares)	319,538,901	319,538,901	319,080,678	319,080,678
Treasury shares, at cost (in shares)	2,863,267	2,863,267	2,863,267	2,863,267

CONDENSED CONSOLIDATED STATEMENTS OF EQUITY (Unaudited) (USD $) In Millions	Total	Total controlling interest shareholders' equity [Member]	Shares [Member]	Additional paid-in capital [Member]	Treasury shares, at cost [Member]	Retained earnings [Member]	Accumulated other comprehensive loss [Member]	Total noncontrolling interest [Member]
Balance, beginning of period at Dec. 31, 2009	$ 20,559	$ 20,552	$ 4,472	$ 7,407	$ 0	$ 9,008	$ (335)	$ 7
Balance, beginning of period (in shares) at Dec. 31, 2009			321
Issuance of shares under share-based compensation plans (in shares)			1
Issuance of shares under share-based compensation plans	(4)	(4)	6	(10)
Purchases of shares held in treasury (in shares)			(1)
Purchases of shares held in treasury	(60)	(60)			(60)
Share-based compensation	35	35		35
Net income attributable to controlling interest	685					677
Other comprehensive income (loss) attributable to controlling interest	(10)						(3)
Total comprehensive income attributable to controlling interest	674
Total comprehensive income attributable to controlling interest	675	674
Other, net	1	1		1
Balance, end of period at Mar. 31, 2010	21,206	21,198	4,478	7,433		9,685	(338)	8
Balance, end of period (in shares) at Mar. 31, 2010			321		(60)
Balance, beginning of period at Dec. 31, 2010	21,375	21,383	4,482	7,504	(240)	9,969	(332)	(8)
Balance, beginning of period (in shares) at Dec. 31, 2010			319
Issuance of shares under share-based compensation plans (in shares)			1
Issuance of shares under share-based compensation plans	(10)	(10)	6	(16)
Purchases of shares held in treasury (in shares)			0
Purchases of shares held in treasury	0	0			0
Share-based compensation	27	27		27
Net income attributable to controlling interest	340					310
Other comprehensive income (loss) attributable to controlling interest	1						(3)
Total comprehensive income attributable to controlling interest	307	307
Total comprehensive income attributable to controlling interest	341
Other, net	3	3		3
Balance, end of period at Mar. 31, 2011	$ 21,705	$ 21,710	$ 4,488	$ 7,518	$ (240)	$ 10,279	$ (335)	$ (5)
Balance, end of period (in shares) at Mar. 31, 2011			320

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2011	Mar. 31, 2010
Cash flows from operating activities
Net income	$ 340	$ 685
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of drilling contract intangibles	(10)	(33)
Depreciation and amortization	354	374
Share - based compensation expense	27	35
Gain on disposal of discontinued operations	(173)	0
(Gain) loss on disposal of assets, net	(8)	14
Amortization of debt issue costs, discounts and premiums, net	26	49
Deferred income taxes	11	(22)
Other, net	(3)	31
Deferred revenue, net	46	151
Deferred expenses, net	(36)	(14)
Changes in operating assets and liabilities	(184)	(98)
Net cash provided by operating activities	390	1,172
Cash flows from investing activities
Capital expenditures	(240)	(369)
Proceeds from disposal of assets, net	13	41
Proceeds from disposal of discontinued operations	259	0
Other, net	(6)	5
Net cash provided by (used in) investing activities	26	(323)
Cash flows from financing activities
Change in short - term borrowings, net	51	(131)
Proceeds from debt	5	54
Repayments of debt	(47)	(253)
Purchases of shares held in treasury	0	(60)
Other, net	(7)	(3)
Net cash provided by (used in) financing activities	2	(393)
Net increase in cash and cash equivalents	418	456
Cash and cash equivalents at beginning of period	3,394	1,130
Cash and cash equivalents at end of period	$ 3,812	$ 1,586

Nature of Business	3 Months Ended
Nature of Business	Mar. 31, 2011
Nature of Business [Abstract]
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. Our mobile offshore drilling fleet is considered one of the most modern and versatile fleets in the world. Specializing in technically demanding sectors of the offshore drilling business with a particular focus on deepwater and harsh environment drilling services, we contract our drilling rigs, related equipment and work crews predominantly on a dayrate basis to drill oil and gas wells. At March 31, 2011, we owned or had partial ownership interests in and operated 137 mobile offshore drilling units. As of this date, our fleet consisted of 47 High-Specification Floaters (Ultra-Deepwater, Deepwater and Harsh Environment semisubmersibles and drillships), 25 Midwater Floaters, nine High-Specification Jackups, 53 Standard Jackups and three Other Rigs. We also have one Ultra-Deepwater Floater and three High-Specification Jackups under construction (see Note 7-Drilling Fleet and Note 15-Subsequent Events). 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. We also participated in oil and gas exploration, development and production activities through our oil and gas subsidiaries, Challenger Minerals Inc. and Challenger Minerals (North Sea) Limited (together, “CMI”), which were classified as discontinued operations as of March 31, 2011. See Note 5-Discontinued Operations.

Significant Accounting Policies	3 Months Ended
Significant Accounting Policies	Mar. 31, 2011
Significant Accounting Policies [Abstract]
Significant Accounting Policies [Text Block]	Note 2-Significant Accounting Policies Basis of presentation-We have prepared our accompanying unaudited condensed consolidated financial statements in accordance with accounting principles generally accepted in the United States (“U.S.”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X of the U.S. Securities and Exchange Commission (“SEC”). Pursuant to such rules and regulations, these financial statements do not include all disclosures required by accounting principles generally accepted in the U.S. for complete financial statements. The condensed consolidated financial statements reflect all adjustments, which are, in the opinion of management, necessary for a fair presentation of financial position, results of operations and cash flows for the interim periods. Such adjustments are considered to be of a normal recurring nature unless otherwise noted. Operating results for the three months ended March 31, 2011 are not necessarily indicative of the results that may be expected for the year ending December 31, 2011 or for any future period. The accompanying condensed consolidated financial statements and notes thereto should be read in conjunction with the audited consolidated financial statements and notes thereto as of December 31, 2010 and 2009 and for each of the three years ended December 31, 2010 included in our annual report on Form 10-K filed on February 28, 2011. Accounting estimates-To prepare financial statements in accordance with accounting principles generally accepted in the U.S., we are required to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosures of contingent assets and liabilities. On an ongoing basis, we evaluate our estimates and assumptions, including those related to our allowance for doubtful accounts, materials and supplies obsolescence, property and equipment, investments, notes receivable, goodwill and other intangible assets, income taxes, defined benefit pension plans and other postretirement benefits, contingencies and share-based compensation. 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) unadjusted quoted prices for identical assets or liabilities in active markets (“Level 1”), (2) direct or indirect observable inputs, including quoted prices or other market data, for similar assets or liabilities in active markets or identical assets or liabilities in less active markets (“Level 2”) and (3) unobservable inputs 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. Principles of 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 3-Variable Interest Entities. Share-based compensation-Share-based compensation expense was $27 million and $35 million for the three months ended March 31, 2011 and March 31, 2010, respectively. Capitalized interest-We capitalize interest costs for qualifying construction and upgrade projects. We capitalized interest costs on construction work in progress of $15 million and $28 million for the three months ended March 31, 2011 and March 31, 2010, respectively. Reclassifications-We have made certain reclassifications to prior period amounts to conform with the current period's presentation. We have made certain reclassifications to our condensed consolidated statement of financial position, results of operations and cash flows to present our oil and gas properties reporting unit and our Caspian Sea operations as discontinued operations (see Note 5-Discontinued Operations). Other reclassifications did not have a material effect on our condensed 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 15-Subsequent Events.

Variable Interest Entities

3 Months Ended

Mar. 31, 2011

Variable Interest Entity [Abstract]

Variable Interest Entities [Text Block]

Note 3-Variable Interest Entities

Consolidated variable interest entities-We consolidate the assets and liabilities of Transocean Pacific Drilling Inc. (“TPDI”), a consolidated British Virgin Islands joint venture company, and Angola Deepwater Drilling Company Limited (“ADDCL”), a consolidated Cayman Islands joint venture company, which are two variable interest entities for which we are the primary beneficiary. The carrying amounts associated with our consolidated variable interest entities, after eliminating the effect of intercompany transactions, were as follows (in millions):

	March 31, 2011						December 31, 2010
	Assets		Liabilities		Net carrying amount		Assets		Liabilities		Net carrying amount
Variable interest entity
TPDI	$	1,575	$	724	$	851	$	1,598	$	763	$	835
ADDCL		898		356		542		864		345		519
Total	$	2,473	$	1,080	$	1,393	$	2,462	$	1,108	$	1,354

Unconsolidated variable interest entity-As holder of two notes receivable and a lender under a working capital loan, we hold a variable interest in Awilco Drilling Limited (“ADL”), a U.K. company (see Note 7-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. We also provide ADL with a working capital loan, which is also secured by the drilling units, with a maximum borrowing amount of $35 million. We evaluate the credit quality and financial condition of ADL quarterly. The aggregate carrying amount of the notes receivable was $110 million and $109 million at March 31, 2011 and December 31, 2010, respectively. The aggregate carrying amount of working capital loan receivable was $6 million at March 31, 2011 and December 31, 2010.

- 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

Income Taxes

3 Months Ended

Mar. 31, 2011

Income Taxes [Abstract]

Income Taxes [Text Block]

Note 4-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. There is little to no expected relationship between the provision for or benefit from income taxes and income or loss before income taxes considering, among other factors, (a) changes in the blend of income that is taxed based on gross revenues rather than income before taxes, (b) rig movements between taxing jurisdictions and (c) our rig operating structures.

Our estimated annual effective tax rates for the three months ended March 31, 2011 and March 31, 2010 were 19.3 percent and 15.2 percent, respectively. These rates were based on estimated annual income before income taxes for each period after adjusting for various discrete items, including certain immaterial adjustments to prior period tax expense.

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

		March 31, 2011				December 31, 2010
Valuation allowance for non-current deferred tax assets		$	94			$	94

Unrecognized tax benefits-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):

	March 31, 2011		December 31, 2010
Unrecognized tax benefits, excluding interest and penalties	$	501	$	485
Interest and penalties		244		235
Unrecognized tax benefits, including interest and penalties	$	745	$	720

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 2000. For the three months ended March 31, 2011 and March 31, 2010, 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 other major jurisdictions in which we operate are generally subject to examination for periods ranging from three to six years. We have agreed to extensions beyond the statute of limitations in four major jurisdictions for up to 16 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 and 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 $79 million, exclusive of interest. We believe an unfavorable outcome on this assessment with respect to 2004 and 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 August 2010, we filed a petition with the U.S. Tax Court in an attempt to resolve this issue.

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 2006, 2007, 2008 and 2009 tax returns. 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 into 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 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 $166 million, exclusive of 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 $92 million, exclusive of interest. We believe that our tax returns are materially correct as filed, and we intend to vigorously defend against any potential claims.

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 of our former external advisors on these transactions. The authorities issued tax assessments of (a) approximately $283 million plus interest, related to certain restructuring transactions, (b) approximately $124 million plus interest, related to the migration of a subsidiary that was previously subject to tax in Norway, (c) approximately $75 million plus interest, related to a 2001 dividend payment and (d) approximately $8 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. We may be required to provide some form of financial security, in an amount up to $1.1 billion, including interest and penalties, for these assessed amounts as this dispute is 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. We intend to vigorously contest any assertions by the Norwegian authorities in connection with the various transactions being investigated. An unfavorable outcome on these Norwegian civil 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.

The Norwegian authorities issued notification of criminal charges against Transocean Ltd. and certain of its subsidiaries related to disclosures included in one of our Norwegian tax returns. This notification, however, does not itself constitute an indictment under Norwegian law nor does it initiate legal proceedings but represents a formal expression of suspicion and continued investigation. All income taxes, interest charges and penalties related to this Norwegian tax return have previously been settled. We believe that these charges are without merit and plan to vigorously defend Transocean Ltd. and its subsidiaries to the fullest extent.

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 $119 million, plus a 75 percent penalty of $89 million and $144 million of interest through March 31, 2011. 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

3 Months Ended

Mar. 31, 2011

Discontinued Operations [Abstract]

Discontinued Operations

Note 5-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. We expect the disposal of the assets in this reporting unit to be completed within 12 months and, accordingly, have classified the oil and gas properties and related assets as assets held for sale as of March 31, 2011.

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 $173 million ($0.54 per diluted share from discontinued operations), which had no tax effect. We have agreed to continue operating Trident 20 under a bareboat charter to perform services for an approximate break-even amount under a contract with the customer, which we expect to continue for a period less than 12 months.

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

	Three months ended March 31,
	2011		2010
Operating revenues	$	26	$	23
Costs and expenses		23		39
Income (loss) from discontinued operations before income tax expense		3		(16	)
Income tax benefit		-		18
Gain on disposal of discontinued operations		173		-

Income from discontinued operations, net of tax	$	176	$	2

Assets and liabilities of discontinued operations-At March 31, 2011, we have classified our oil and gas properties and related assets as assets held for sale. As a result of our decision to discontinue these operations and those of our Caspian Sea subsidiary, we have reclassified the assets and liabilities related to these discontinued operations to other current assets, other assets, other current liabilities and other long-term liabilities, at December 31, 2010. The carrying amounts of the major classes of assets and liabilities associated with these operations were classified as follows (in millions):

	March 31, 2011		December 31, 2010
Assets
Oil and gas properties, net	$	56	$	-
Other related assets		13		-
Assets held for sale	$	69	$	-

Accounts receivable	$	17	$	22
Other assets		13		17
Other current assets	$	30	$	39

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

Liabilities
Accounts payable	$	19	$	15
Other liabilities		28		13
Other current liabilities	$	47	$	28

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

Earnings Per Share

3 Months Ended

Mar. 31, 2011

Earnings Per Share [Abstract]

Earnings Per Share

Note 6-Earnings Per Share

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

	Three months ended March 31,
	2011						2010
	Basic			Diluted			Basic			Diluted
Numerator for earnings per share							(As adjusted)			(As adjusted)
Income from continuing operations attributable to controlling interest	$	134		$	134		$	675		$	675
Undistributed earnings allocable to participating securities		(1	)		(1	)		(4	)		(4	)
Income from continuing operations available to shareholders	$	133		$	133		$	671		$	671

Denominator for earnings per share
Weighted-average shares outstanding		319			319			321			321
Effect of stock options and other share-based awards		-			1			-			1
Weighted-average shares for per share calculation		319			320			321			322

Per share earnings from continuing operations	$	0.42		$	0.42		$	2.09		$	2.08

We have excluded 1.2 million and 1.1 million share-based awards, from the calculation since the effect would have been anti-dilutive for the three months ended March 31, 2011 and 2010, respectively. 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 8-Debt).

Drilling Fleet

3 Months Ended

Mar. 31, 2011

Drilling Fleet [Abstract]

Drilling Fleet [Text Block]

Note 7-Drilling Fleet

Expansion-Construction work in progress, recorded in property and equipment, was $1.5 billion at March 31, 2011 and December 31, 2010. Capital expenditures and other capital additions, including capitalized interest, for our major construction projects that were ongoing during the three months ended March 31, 2011 or during the year ended December 31, 2010 were as follows (in millions):

	Three months ended March 31, 2011		Through December 31, 2010		Total costs
Transocean Honor (a)	$	47	$	97	$	144
Deepwater Champion (b)		23		733		756
High-Specification Jackup TBN1 (c)		10		9		19
High-Specification Jackup TBN2 (c)		10		9		19
Discoverer Luanda (d)(e)		8		709		717
Discoverer India (d)		-		744		744
Discoverer Inspiration (d)		-		679		679
Dhirubhai Deepwater KG2 (d)(f)		-		677		677
Capitalized interest		15		273		288
Mobilization costs		13		100		113
Total	$	126	$	4,030	$	4,156

__________________________

(a)

In November 2010, we made an initial installment payment of $97 million to purchase a PPL Pacific Class 400 design jackup, to be named Transocean Honor, for $195 million. The High-Specification Jackup is under construction at PPL Shipyard Pte Ltd. in Singapore and is expected for delivery in the fourth quarter of 2011.

(b)	These costs include our initial investment in Deepwater Champion of $109 million, representing the estimated fair value of the rig at the time of our merger with GlobalSantaFe Corporation (“GlobalSantaFe”) in November 2007.

(c)

In December 2010, we made initial installment payments of $9 million each to purchase two Keppel FELS Super B class design jackups for $186 million each. The two High-Specification Jackups are under construction at Keppel FELS's yard in Singapore and are expected for delivery in the first quarter of 2013.

(d)	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 March 31, 2011.

(e)	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 ADDCL, and Angco Cayman Limited holds the remaining 35 percent interest.

(f)

The costs for 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 TPDI, and Quantum Pacific Management Limited, a Cypriot company and successor in interest to Pacific Drilling Limited (“Quantum”), holds the remaining 50 percent interest.

Dispositions-During the three months ended March 31, 2011, in connection with our efforts to dispose of non-strategic assets, we sold the High-Specification Jackup Trident 20 and the Standard Jackup Transocean Mercury. The sale of Trident 20 reflected our decision to discontinue operations in the Caspian Sea (see Note 5-Discontinued Operations). In connection with the sale of Transocean Mercury, we received net cash proceeds of $10 million and recognized a gain on disposal of the drilling unit of $9 million ($0.03 per diluted share from continuing operations), which had no tax effect. For the three months ended March 31, 2011, we recognized a net loss on disposal of unrelated assets in the amount of $1 million.

During the three months ended March 31, 2010, we sold two Midwater Floaters, GSF Arctic II and GSF Arctic IV. In connection with the sales, 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 3-Variable Interest Entities). We operated GSF Arctic IV under a short-term bareboat charter with the new owner of the vessel until November 2010. As a result of the sales, we recognized a loss on disposal of assets in the amount of $15 million ($0.05 per diluted share from continuing operations), which had no tax effect for the three months ended March 31, 2010. For the three months ended March 31, 2010, we recognized a gain on disposal of unrelated assets in the amount of $1 million.

Assets held for sale-In March 2011, in addition to our plan to sell the assets associated with our oil and gas properties reporting unit (see Note 5-Discontinued Operations), we also committed to a plan to sell our Standard Jackup GSF Britannia and related equipment. At March 31, 2011, GSF Britannia was classified as held for sale with a net carrying amount of $8 million. At December 31, 2010, Transocean Mercury was classified as held for sale with a net carrying amount of less than $1 million.

Debt

3 Months Ended

Mar. 31, 2011

Debt [Abstract]

Debt [Text Block]

Note 8-Debt

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

	March 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	$	5	$	-	$	5	$	10	$	-	$	10
Commercial paper program (a)		139		-		139		88		-		88
6.625% Notes due April 2011 (a)		166		-		166		167		-		167
5% Notes due February 2013		254		-		254		255		-		255
5.25% Senior Notes due March 2013 (a)		510		-		510		511		-		511
TPDI Credit Facilities due March 2015		-		525		525		-		560		560
4.95% Senior Notes due November 2015 (a)		1,099		-		1,099		1,099		-		1,099
ADDCL Credit Facilities due December 2017		-		242		242		-		242		242
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
8% Debentures due April 2027 (a)		57		-		57		57		-		57
7.45% Notes due April 2027 (a)		96		-		96		96		-		96
7% Notes due June 2028		312		-		312		313		-		313
Capital lease contract due August 2029		689		-		689		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)		1,639		-		1,639		1,625		-		1,625
1.50% Series C Convertible Senior Notes due December 2037 (a)		1,619		-		1,619		1,605		-		1,605
6.80% Senior Notes due March 2038 (a)		999		-		999		999		-		999
Total debt		10,326		915		11,241		10,271		950		11,221
Less debt due within one year
ODL Loan Facility		5		-		5		10		-		10
Commercial paper program (a)		139		-		139		88		-		88
6.625% Notes due April 2011 (a)		166		-		166		167		-		167
TPDI Credit Facilities due March 2015		-		70		70		-		70		70
ADDCL Credit Facilities due December 2017		-		25		25		-		25		25
Capital lease contract due August 2029		16		-		16		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)		1,639		-		1,639		1,625		-		1,625
Total debt due within one year		1,965		95		2,060		1,917		95		2,012
Total long-term debt	$	8,361	$	820	$	9,181	$	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. has no independent assets or operations, its guarantee of debt securities of Transocean Inc. is full and unconditional and its only other subsidiary not owned indirectly through Transocean Inc. is minor. Transocean Inc.'s only operating assets are its investments in its operating subsidiaries. Transocean Inc.'s independent assets and operations, other than those related to investments in its subsidiaries and balances primarily pertaining to its cash and cash equivalents and debt are less than one percent of the total consolidated assets and operations of Transocean Ltd., and thus, substantially all of the assets and operations exist within these non-guarantor operating companies. Furthermore, Transocean Ltd. and Transocean Inc. are not subject to any significant restrictions on their ability to obtain funds from their consolidated subsidiaries or entities accounted for under the equity method by dividends, loans or return of capital distributions.

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 B Convertible Senior Notes and 1.50% Series C Convertible Senior Notes in December 2011 and 2012, respectively. At March 31, 2011, the scheduled maturities of our debt were as follows (in millions):

	Transocean Ltd. and subsidiaries			Consolidated variable interest entities		Consolidated total
Twelve months ending March 31,
2012	$	2,005		$	95	$	2,100
2013		2,491			97		2,588
2014		21			98		119
2015		22			345		367
2016		1,124			60		1,184
Thereafter		4,791			220		5,011
Total debt, excluding unamortized discounts, premiums and fair value adjustments		10,454			915		11,369
Total unamortized discounts, premiums and fair value adjustments		(128	)		-		(128	)
Total debt	$	10,326		$	915	$	11,241

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 March 31, 2011, $139 million in commercial paper was outstanding at a weighted-average interest rate of 0.9 percent, including commissions.

Five-Year Revolving Credit Facility-We have a $2.0 billion, five-year revolving credit facility under the Five-Year Revolving Credit Facility Agreement dated November 27, 2007, as amended (the “Five-Year Revolving Credit Facility”). 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 0.10 percent to 0.30 percent, based on our debt rating, and was 0.175 percent at March 31, 2011. At March 31, 2011, we had $71 million in letters of credit issued and outstanding, we had $1.9 billion available borrowing capacity and we had no borrowings outstanding under the Five-Year Revolving Credit Facility.

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 term loans with an aggregate commitment of $595 million. At March 31, 2011, $1.1 billion was outstanding under the TPDI Credit Facilities, of which $525 million was due to one of our subsidiaries and was eliminated in consolidation. The weighted-average interest rate on March 31, 2011 was 1.9 percent. See Note 9-Derivatives and Hedging and Note 11-Contingencies.

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 March 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 March 31, 2011 was 2.5 percent.

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 the borrowings under Tranche A. One of our subsidiaries provides the commitment for and the borrowings under Tranche C. At March 31, 2011, $215 million was outstanding under Tranche A at a weighted-average interest rate of 1.2 percent. At March 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”), for which one of our subsidiaries provides 65 percent of the total commitment. At March 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 March 31, 2011 was 3.4 percent.

1.625% Series A, 1.50% Series B and 1.50% Series C Convertible Senior Notes-The carrying amounts of the liability components of the Convertible Senior Notes were as follows (in millions):

	March 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		1,680		(41	)		1,639		1,680		(55	)		1,625
Series C Convertible Senior Notes due 2037		1,722		(103	)		1,619		1,722		(117	)		1,605

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

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

Including the amortization of the unamortized discount, the effective interest rates were 5.08 percent for the Series B Convertible Senior Notes and 5.28 percent for the Series C Convertible Senior Notes. At March 31, 2011, the remaining period over which the discount will be amortized was less than one year for the Series B Convertible Senior Notes and 1.6 years for the Series C Convertible Senior Notes. Interest expense, excluding amortization of debt issue costs, was as follows (in millions):

	Three months ended March 31,
	2011		2010
Interest expense
Series A Convertible Senior Notes due 2037	$	-	$	15
Series B Convertible Senior Notes due 2037		20		26
Series C Convertible Senior Notes due 2037		20		26

On January 31, 2011, we redeemed the remaining aggregate principal amount of $11 million of our Series A Convertible Senior Notes for an aggregate cash payment of $11 million, and none remained outstanding as of March 31, 2011.

Derivatives and Hedging	3 Months Ended
Derivatives and Hedging	Mar. 31, 2011
Derivatives and Hedging [Abstract]
Derivatives and Hedging [Text Block]	Note 9-Derivatives and Hedging Cash flow hedges-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 amount of the outstanding borrowings under the TPDI Credit Facilities. As of March 31, 2011, the aggregate notional amount was $1.1 billion, of which $525 million was attributable to the intercompany borrowings provided by one of our subsidiaries and the related balances have been eliminated in consolidation. At March 31, 2011, the weighted-average variable interest rate associated with the interest rate swaps was 0.3 percent, and the weighted-average fixed interest rate was 2.3 percent. At March 31, 2011, the interest rate swaps represented a liability measured at a fair value of $10 million, recorded in other long-term liabilities, with a corresponding increase to accumulated other comprehensive loss. At December 31, 2010, the interest rate swaps represented a liability measured at a fair value of $13 million, recorded in other long-term liabilities, with a corresponding increase to accumulated other comprehensive loss. The amount associated with the ineffective portion of the cash flow hedges was less than $1 million, recorded in interest expense for the three months ended March 31, 2011. The ineffective portion of the cash flow hedges was less than $1 million recorded in interest expense for the three months ended March 31, 2010. Fair value hedges-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 5.25% Senior Notes and the 5.00% Notes. The interest rate swaps have aggregate notional amounts of $500 million and $250 million, respectively, equal to the 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. At March 31, 2011, the weighted-average variable interest rate on the interest rate swaps was 3.5 percent, and the fixed interest rates matched those of the underlying debt instruments. At March 31, 2011, the interest rate swaps represented an asset measured at fair value of $15 million, recorded in other assets, with a corresponding increase to the carrying amounts of the underlying debt instruments. At December 31, 2010, the interest rate swaps represented an asset measured at fair value of $17 million, recorded in other assets, with a corresponding increase to the carrying amounts of the underlying debt instruments.

Postemployment Benefit Plans

3 Months Ended

Mar. 31, 2011

Postemployment Benefit Plans [Abstract]

Postemployment Benefit Plans [Text Block]

Note 10-Postemployment Benefit Plans

Defined benefit pension plans and other postretirement employee benefit plans-We have several defined benefit pension plans, both funded and unfunded, covering substantially all of our U.S. employees, including certain frozen plans, assumed in connection with our mergers, that cover certain current employees and certain former employees and directors of our predecessors (the “U.S. Plans”). We also have various defined benefit plans in the U.K., Norway, Nigeria, Egypt and Indonesia that cover our employees in those areas (the “Non-U.S. Plans”). Additionally, we offer several unfunded contributory and noncontributory other postretirement employee benefit plans covering substantially all of our U.S. employees (the “OPEB Plans”).

The components of net periodic benefit costs, before tax, and funding contributions for these plans were as follows (in millions):

	Three months ended March 30, 2011											Three months ended March 31, 2010
	U.S. Plans			Non-U.S. Plans			OPEB Plans		Total			U.S. Plans			Non-U.S. Plans			OPEB Plans			Total
Net periodic benefit costs
Service cost	$	11		$	5		$	-	$	16		$	10		$	6		$	-		$	16
Interest cost		14			5			1		20			14			5			1			20
Expected return on plan assets		(16	)		(5	)		-		(21	)		(14	)		(5	)		-			(19	)
Settlements and curtailments		-			-			-		-			-			1			-			1
Actuarial losses, net		6			-			-		6			3			1			-			4
Prior service cost, net		-			-			-		-			-			-			(1	)		(1	)
Net periodic benefit costs	$	15		$	5		$	1	$	21		$	13		$	8		$	-		$	21

Funding contributions	$	13		$	7		$	1	$	21		$	2		$	4		$	2		$	8

- 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

Contingencies

3 Months Ended

Mar. 31, 2011

Contingencies [Abstract]

Contingencies [Text Block]

Note 11-Contingencies

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.

As we continue to investigate the cause or causes of the incident, we are evaluating its consequences. Although we cannot predict the final outcome or estimate the reasonably possible range of loss with certainty, we have recognized a liability for estimated loss contingencies that we believe are probable and for which a reasonable estimate can be made. We have also recognized a receivable for the portion of this liability that we believe is recoverable from insurance. As of March 31, 2011, the amount of the estimated liability was approximately $170 million, recorded in other current liabilities, and the corresponding estimated recoverable amount was approximately $130 million, recorded in accounts receivable, net, on our consolidated balance sheet. New information or future developments could require us to adjust our disclosures and our estimated liabilities and insurance recoveries. See “-Contractual indemnity” and Note 15-Subsequent Events.

Litigation-Numerous actions or claims are pending against Transocean entities, 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. Third parties have also, based on contractual arrangements, 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 third parties. See “-Contractual indemnity.”

Wrongful death and personal injury-As of March 31, 2011, we and one or more of our subsidiaries have been named, along with other unaffiliated defendants, in 31 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. The complaints generally allege negligence and seek awards of unspecified economic damages and punitive damages. See “-Contractual indemnity.”

Environmental pollution and economic loss-As of March 31, 2011, we and one or more of our subsidiaries were named, along with other unaffiliated defendants, in 61 individual complaints as well as 179 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 Oil Pollution Act of 1990 (“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. Two 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 third 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.

Shareholder derivative claims-In June 2010, two shareholder derivative suits were filed by certain of 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 Transocean, restitution and disgorgement of all profits, benefits and other compensation from the defendants.

Government claims-On December 15, 2010, the Department of Justice (the “DOJ”) filed a civil lawsuit against us and other unaffiliated defendants. The complaint alleges violations under OPA and the Clean Water Act, and the DOJ reserved its rights to amend the complaint to add new claims and defendants. The complaint asserts that all defendants named are jointly and severally liable for all removal costs and damages resulting from the Macondo well incident. In addition to the civil complaint, the DOJ served us with civil investigative demands on December 8, 2010. These demands are part of an ongoing investigation by the DOJ to determine if we made false 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. See Note 15-Subsequent Events.

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, as well as the Mexican States of Veracruz, Quintana Roo and Tamaulipas. Generally, these governmental entities allege economic losses under OPA and other statutory environmental state claims and also assert various common law state claims.

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 lawsuit filed by the State of Alabama 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 are reviewing the results. 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 may seek 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. See Note 15-Subsequent Events.

Insurance coverage-In May 2010, we received notice from the operator under the drilling contract for Deepwater Horizon maintaining that it believes that it is entitled to additional insured status as provided for under the drilling contract. In response, many of our insurers filed declaratory judgment actions in May 2010, seeking a judgment declaring that they have limited additional-insured obligation to the operator. These actions have been transferred to the Multi-District Litigation Panel (“MDL”) with respect to the Macondo well incident for discovery purposes.

Other legal proceedings

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. A Special Master, appointed to administer these cases pre-trial, subsequently required that each individual plaintiff 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 products 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. 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. In 2009, two cases that were part of the original 2004 multi-plaintiff suits went to trial in Mississippi against unaffiliated defendant companies which allegedly manufactured drilling-related products containing asbestos. We were not a defendant in either of these cases. One of the cases resulted in a substantial jury verdict in favor of the plaintiff, but this verdict was subsequently vacated by the trial judge 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 has not yet been reviewed on appeal. The second case resulted in a verdict completely in favor of the defendants. Two cases went to trial in 2010, one resulting in a substantial verdict for the plaintiff and one resulting in a complete verdict for the defendants. We were not a defendant in either case and both of the matters are currently on appeal. 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 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 March 31, 2011, the subsidiary was a defendant in approximately 1,028 lawsuits. Some of these lawsuits include multiple plaintiffs and we estimate that there are approximately 2,438 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 March 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 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 $197 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 these assessments are without merit. We have challenged the assessments and the cases are still pending a final decision at the administrative level. 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 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.

Patent litigation-In 2007, several of our subsidiaries were sued by Heerema Engineering Services (“Heerema”) in the United States District Court for the Southern District of Texas for patent infringement, claiming that we infringe their U.S. patent entitled Method and Device for Drilling Oil and Gas. Heerema claims that our Enterprise class, advanced Enterprise class, Express class and Development Driller class of drilling rigs operating in the U.S. Gulf of Mexico infringe on this patent. Heerema seeks unspecified damages and injunctive relief. The court has held a hearing on construction of Heerema's patent but has not yet issued a decision. We deny liability for patent infringement, believe that Heerema's patent is invalid and intend to vigorously defend against the claim. We do not expect the liability, if any, resulting from this claim 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 March 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 financial position, or ongoing 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 of its 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 recently joined 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.

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 these theories 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 primarily with 12-month and 11-month policy periods beginning on May 1, 2010 and June 1, 2010, respectively. As of March 31, 2011, the insured value of our drilling rig fleet was approximately $38.5 billion in the aggregate, excluding 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, the shared deductible is $0 in the event of a total loss or a constructive total loss of a drilling unit.

We carry $950 million of commercial market excess liability coverage, exclusive of 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. These types of excess liability coverages are subject to an additional aggregate self-insured retention of $50 million that is applied to any occurrence in excess of the per occurrence deductible until the $50 million is exhausted. 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 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. Except with respect to Dhirubhai Deepwater KG1 and Dhirubhai Deepwater KG2, we generally do not carry insurance for loss of revenue unless contractually required.

Letters of credit and surety bonds

We had letters of credit outstanding totaling $641 million and $595 million at March 31, 2011 and December 31, 2010, respectively. These letters of credit guarantee various contract bidding and performance activities under various committed and uncommitted credit lines provided by several banks.

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, which is included in the total as of March 31, 2011. The letter of credit was issued under an uncommitted credit facility that has been established by one of our subsidiaries. See Note 8-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 $24 million and $27 million at March 31, 2011 and December 31, 2010, respectively.

Redeemable Noncontrolling Interest

3 Months Ended

Mar. 31, 2011

Redeemable Noncontrolling Interest [Abstract]

Redeemable Noncontrolling Interest

Note 12-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 condensed consolidated balance sheets. Changes in redeemable noncontrolling interest were as follows (in millions):

	Three months ended March 31,
	2011		2010 (a)
Redeemable noncontrolling interest
Balance, beginning of period	$	25	$	-
Net income attributable to noncontrolling interest		28		-
Other comprehensive income attributable to noncontrolling interest		4		-
Balance, end of period	$	57	$	-

______________________________

(a)	The noncontrolling interest associated with TPDI was not redeemable during the three months ended March 31, 2010.

Shareholders' Equity	3 Months Ended
Shareholders' Equity	Mar. 31, 2011
Shareholders' Equity [Abstract]
Shareholders' Equity	Note 13-Shareholders' Equity Distribution-In May 2010, at our annual general meeting, our shareholders approved a cash distribution in the form of a par value reduction in the aggregate amount of CHF 3.44 per issued share, equal to approximately $3.74, using an exchange rate of USD 1.00 to CHF 0.92 as of the close of trading on March 31, 2011. According to the May 2010 shareholder resolution and pursuant to applicable Swiss law, we were required to submit an application to the Commercial Register of the Canton of Zug in relation to each quarterly installment to register the relevant partial par value reduction, together with, among other things, a compliance deed issued by an independent notary public. On August 13, 2010, the Commercial Register of the Canton of Zug rejected our application to register the first of the four partial par value reductions. We appealed the Commercial Register's decision, and on December 9, 2010, the Administrative Court of the Canton of Zug rejected our appeal. The Administrative Court held that the statutory requirements for the registration of the par value reduction in the commercial register could not be met given the existence of lawsuits filed in the United States related to the Macondo well incident that were served in Switzerland and the reference to such lawsuits in the compliance deed. The Administrative Court's opinion also held that under these circumstances it was not possible to submit an amended compliance deed. Based on these considerations, we do not believe that a financial obligation existed for the distribution. On January 24, 2011, we filed an appeal on the decision of the Administrative Court of the Canton of Zug to the Swiss Federal Supreme Court. On February 11, 2011, our board of directors recommended that shareholders at the May 2011 annual general meeting approve a U.S. dollar-denominated dividend of approximately U.S. $1 billion out of additional paid-in capital and payable in four installments. The board's determination of the timing of these installments is expected to depend on, among other things, developments in the Swiss political and legal arenas. The proposed dividend will, among other things, be contingent on shareholders approving at the same meeting a rescission of the 2010 distribution. Due to, among other things, the uncertainty of the timing and outcome of the pending appeal with the Swiss Federal Supreme Court, our board of directors believes it is in our best interest to discontinue with the disputed 2010 distribution. We filed a request to stay the pending appeal with the Swiss Federal Supreme Court against the decision of the Administrative Court until shareholders have voted on the proposed rescission, and such stay was granted on March 7, 2011. 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 both March 31, 2011 and December 31, 2010, our subsidiary held approximately 13 million shares.

- 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

Fair Value of Financial Instruments

3 Months Ended

Mar. 31, 2011

Fair Value of Financial Instruments [Abstract]

Fair Value of Financial Instruments

Note 14-Fair Value of Financial Instruments

We estimate 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 estimated fair value, measured using unobservable inputs that require significant judgment, for which there is little or no market data, including the credit rating of the borrower. At March 31, 2011, the aggregate carrying amount of our notes receivable and working capital loan receivable was $116 million, including $6 million and $110 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.

Debt-The fair value of our fixed-rate debt is measured using direct or indirect observable inputs, including quoted prices or other market data, for similar assets or liabilities in active markets or identical assets or liabilities in less active markets. Our variable-rate debt is included in the fair values stated below at its carrying amount since the short-term interest rates cause the face value to approximate its fair value. The TPDI Notes and Overseas Drilling Limited (“ODL”) Loan Facility are included in the fair values stated below at their aggregate carrying amount of $153 million and $158 million at March 31, 2011 and December 31, 2010, respectively, since there is no available market price for such related-party debt. The carrying amounts and estimated fair values of our long-term debt, including debt due within one year, were as follows (in millions):

	March 31, 2011				December 31, 2010
	Carrying amount		Fair value		Carrying amount		Fair value

Long-term debt, including current maturities	$	10,326	$	10,771	$	10,271	$	10,562
Long-term debt of consolidated variable interest entities, including current maturities		915		925		950		964

Derivative instruments-The carrying amount of our derivative instruments represents the estimated fair value, measured using direct or indirect observable inputs, including quoted prices or other market data for similar assets or liabilities in active markets or identical assets or liabilities in less active markets. At March 31, 2011, the carrying amounts of our derivative instruments were $15 million and $10 million, recorded in other assets and other long-term liabilities, respectively, on our condensed consolidated balance sheets. At December 31, 2010, the carrying amounts of our derivative instruments were $17 million and $13 million, recorded in other assets and other long-term liabilities, respectively, on our consolidated balance sheets.

- 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

Subsequent Events	3 Months Ended
Subsequent Events	Mar. 31, 2011
Subsequent Events [Abstract]
Subsequent Events	Note 15-Subsequent Events Debt repayments-Subsequent to March 31, 2011, we repaid the remaining aggregate principal amount of $166 million of the 6.625% Notes due April 2011 on the stated maturity date of April 15, 2011. Macondo well incident-In April 2011, several defendants in the Macondo litigation before the MDL filed cross-claims or third-party claims against Transocean entities and other defendants. BP Exploration and Production or its affiliates (“BP”) filed a claim seeking contribution under OPA and maritime law, subrogation and claimed breach of contract, unseaworthiness, negligence and gross negligence. 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. In addition, the DOJ convened a grand jury in Louisiana to investigate potential criminal conduct in connection with the Macondo well incident, and on April 13, 2011, the grand jury issued us a subpoena requesting documents from us.

Significant Accounting Policies (Policies)	3 Months Ended
Significant Accounting Policies (Policies)	Mar. 31, 2011
Significant Accounting Policies [Abstract]
Basis of presentation	Basis of presentation-We have prepared our accompanying unaudited condensed consolidated financial statements in accordance with accounting principles generally accepted in the United States (“U.S.”) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X of the U.S. Securities and Exchange Commission (“SEC”). Pursuant to such rules and regulations, these financial statements do not include all disclosures required by accounting principles generally accepted in the U.S. for complete financial statements. The condensed consolidated financial statements reflect all adjustments, which are, in the opinion of management, necessary for a fair presentation of financial position, results of operations and cash flows for the interim periods. Such adjustments are considered to be of a normal recurring nature unless otherwise noted. Operating results for the three months ended March 31, 2011 are not necessarily indicative of the results that may be expected for the year ending December 31, 2011 or for any future period. The accompanying condensed consolidated financial statements and notes thereto should be read in conjunction with the audited consolidated financial statements and notes thereto as of December 31, 2010 and 2009 and for each of the three years ended December 31, 2010 included in our annual report on Form 10-K filed on February 28, 2011.
Accounting estimates	Accounting estimates-To prepare financial statements in accordance with accounting principles generally accepted in the U.S., we are required to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosures of contingent assets and liabilities. On an ongoing basis, we evaluate our estimates and assumptions, including those related to our allowance for doubtful accounts, materials and supplies obsolescence, property and equipment, investments, notes receivable, goodwill and other intangible assets, income taxes, defined benefit pension plans and other postretirement benefits, contingencies and share-based compensation. We base our estimates and assumptions on historical experience and on various other factors we believe are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying amounts of assets and liabilities that are not readily apparent from other sources. Actual results could differ from such estimates.
Fair value measurements	Fair value measurements-We estimate fair value at a price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants in the principal market for the asset or liability. Our valuation techniques require inputs that we categorize using a three-level hierarchy, from highest to lowest level of observable inputs, as follows: (1) unadjusted quoted prices for identical assets or liabilities in active markets (“Level 1”), (2) direct or indirect observable inputs, including quoted prices or other market data, for similar assets or liabilities in active markets or identical assets or liabilities in less active markets (“Level 2”) and (3) unobservable inputs 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.
Principles of consolidation	Principles of 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 3-Variable Interest Entities.
Share-based compensation	Share-based compensation-Share-based compensation expense was $27 million and $35 million for the three months ended March 31, 2011 and March 31, 2010, respectively.
Capitalized interest	Capitalized interest-We capitalize interest costs for qualifying construction and upgrade projects. We capitalized interest costs on construction work in progress of $15 million and $28 million for the three months ended March 31, 2011 and March 31, 2010, respectively.
Reclassifications	Reclassifications-We have made certain reclassifications to prior period amounts to conform with the current period's presentation. We have made certain reclassifications to our condensed consolidated statement of financial position, results of operations and cash flows to present our oil and gas properties reporting unit and our Caspian Sea operations as discontinued operations (see Note 5-Discontinued Operations). Other reclassifications did not have a material effect on our condensed consolidated statement of financial position, results of operations or cash flows.
Subsequent events	Subsequent events-We evaluate subsequent events through the time of our filing on the date we issue our financial statements. See Note 15-Subsequent Events.

Income Taxes (Tables)

3 Months Ended

Mar. 31, 2011

Income Taxes [Abstract]

Valuation allowance for non-current deferred tax assets

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

		March 31, 2011				December 31, 2010
Valuation allowance for non-current deferred tax assets		$	94			$	94

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):

	March 31, 2011		December 31, 2010
Unrecognized tax benefits, excluding interest and penalties	$	501	$	485
Interest and penalties		244		235
Unrecognized tax benefits, including interest and penalties	$	745	$	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.

+ References+ Details

Discontinued Operations (Tables)

3 Months Ended

Mar. 31, 2011

Discontinued Operations [Abstract]

Discontinued Operations

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

	Three months ended March 31,
	2011		2010
Operating revenues	$	26	$	23
Costs and expenses		23		39
Income (loss) from discontinued operations before income tax expense		3		(16	)
Income tax benefit		-		18
Gain on disposal of discontinued operations		173		-

Income from discontinued operations, net of tax	$	176	$	2

	March 31, 2011		December 31, 2010
Assets
Oil and gas properties, net	$	56	$	-
Other related assets		13		-
Assets held for sale	$	69	$	-

Accounts receivable	$	17	$	22
Other assets		13		17
Other current assets	$	30	$	39

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

Liabilities
Accounts payable	$	19	$	15
Other liabilities		28		13
Other current liabilities	$	47	$	28

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

Drilling Fleet (Tables)

3 Months Ended

Mar. 31, 2011

Drilling Fleet [Abstract]

Actual capital expenditures and other capital additions, including capitalized interest

Capital expenditures and other capital additions, including capitalized interest, for our major construction projects that were ongoing during the three months ended March 31, 2011 or during the year ended December 31, 2010 were as follows (in millions):

	Three months ended March 31, 2011		Through December 31, 2010		Total costs
Transocean Honor (a)	$	47	$	97	$	144
Deepwater Champion (b)		23		733		756
High-Specification Jackup TBN1 (c)		10		9		19
High-Specification Jackup TBN2 (c)		10		9		19
Discoverer Luanda (d)(e)		8		709		717
Discoverer India (d)		-		744		744
Discoverer Inspiration (d)		-		679		679
Dhirubhai Deepwater KG2 (d)(f)		-		677		677
Capitalized interest		15		273		288
Mobilization costs		13		100		113
Total	$	126	$	4,030	$	4,156

__________________________

(a)

(b)	These costs include our initial investment in Deepwater Champion of $109 million, representing the estimated fair value of the rig at the time of our merger with GlobalSantaFe Corporation (“GlobalSantaFe”) in November 2007.

(c)

(d)	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 March 31, 2011.

(e)	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 ADDCL, and Angco Cayman Limited holds the remaining 35 percent interest.

(f)

Debt (Tables)

3 Months Ended

Mar. 31, 2011

Debt [Abstract]

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

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

	March 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	$	5	$	-	$	5	$	10	$	-	$	10
Commercial paper program (a)		139		-		139		88		-		88
6.625% Notes due April 2011 (a)		166		-		166		167		-		167
5% Notes due February 2013		254		-		254		255		-		255
5.25% Senior Notes due March 2013 (a)		510		-		510		511		-		511
TPDI Credit Facilities due March 2015		-		525		525		-		560		560
4.95% Senior Notes due November 2015 (a)		1,099		-		1,099		1,099		-		1,099
ADDCL Credit Facilities due December 2017		-		242		242		-		242		242
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
8% Debentures due April 2027 (a)		57		-		57		57		-		57
7.45% Notes due April 2027 (a)		96		-		96		96		-		96
7% Notes due June 2028		312		-		312		313		-		313
Capital lease contract due August 2029		689		-		689		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)		1,639		-		1,639		1,625		-		1,625
1.50% Series C Convertible Senior Notes due December 2037 (a)		1,619		-		1,619		1,605		-		1,605
6.80% Senior Notes due March 2038 (a)		999		-		999		999		-		999
Total debt		10,326		915		11,241		10,271		950		11,221
Less debt due within one year
ODL Loan Facility		5		-		5		10		-		10
Commercial paper program (a)		139		-		139		88		-		88
6.625% Notes due April 2011 (a)		166		-		166		167		-		167
TPDI Credit Facilities due March 2015		-		70		70		-		70		70
ADDCL Credit Facilities due December 2017		-		25		25		-		25		25
Capital lease contract due August 2029		16		-		16		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)		1,639		-		1,639		1,625		-		1,625
Total debt due within one year		1,965		95		2,060		1,917		95		2,012
Total long-term debt	$	8,361	$	820	$	9,181	$	8,354	$	855	$	9,209

__________________________

(a)

Scheduled maturities of debt

	Transocean Ltd. and subsidiaries			Consolidated variable interest entities		Consolidated total
Twelve months ending March 31,
2012	$	2,005		$	95	$	2,100
2013		2,491			97		2,588
2014		21			98		119
2015		22			345		367
2016		1,124			60		1,184
Thereafter		4,791			220		5,011
Total debt, excluding unamortized discounts, premiums and fair value adjustments		10,454			915		11,369
Total unamortized discounts, premiums and fair value adjustments		(128	)		-		(128	)
Total debt	$	10,326		$	915	$	11,241

Carrying amounts of liability components of convertible senior notes

1.625% Series A, 1.50% Series B and 1.50% Series C Convertible Senior Notes-The carrying amounts of the liability components of the Convertible Senior Notes were as follows (in millions):

	March 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		1,680		(41	)		1,639		1,680		(55	)		1,625
Series C Convertible Senior Notes due 2037		1,722		(103	)		1,619		1,722		(117	)		1,605

Carrying amounts of equity components of convertible senior notes

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

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

Interest expense, excluding amortization of debt issue costs

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

	Three months ended March 31,
	2011		2010
Interest expense
Series A Convertible Senior Notes due 2037	$	-	$	15
Series B Convertible Senior Notes due 2037		20		26
Series C Convertible Senior Notes due 2037		20		26

Fair Value of Financial Instruments (Tables)

3 Months Ended

Mar. 31, 2011

Fair Value of Financial Instruments [Abstract]

Carrying amounts and estimated fair values of long-term debt, including debt due within one year

The carrying amounts and estimated fair values of our long-term debt, including debt due within one year, were as follows (in millions):

	March 31, 2011				December 31, 2010
	Carrying amount		Fair value		Carrying amount		Fair value

Long-term debt, including current maturities	$	10,326	$	10,771	$	10,271	$	10,562
Long-term debt of consolidated variable interest entities, including current maturities		915		925		950		964

- 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

Nature of Business (Details)	Mar. 31, 2011
Nature of Business [Abstract]
Number of mobile offshore drilling units	137
Number of High-Specification Floaters	47
Number of Midwater Floaters	25
Number of High-Specification Jackups	9
Number of Standard Jackups	53
Number of Other Rigs	3
Number of Ultra-Deepwater Floaters under construction	1
Number of High-Specification Jackups under construction	3

Significant Accounting Policies (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2011	Mar. 31, 2010
Share-based compensation [Abstract]
Share-based compensation expense	$ 27	$ 35
Capitalized interest [Abstract]
Capitalized interest costs on construction work in progress	$ 15	$ 28

Variable Interest Entities (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2011	Dec. 31, 2010
Consolidated variable interest entities [Abstract]
Variable interest entities for which we are the primary beneficiary	2
Variable Interest, Carrying Amount [Abstract]
Assets	$ 2,473	$ 2,462
Liabilities	1,080	1,108
Net carrying amount	1,393	1,354
Unconsolidated variable interest entities [Abstract]
Number of notes receivable from sale of Midwater Floaters	2
Number of Midwater Floaters sold	2
Stated interest rate on notes receivable received from sale of Midwater Floaters (in hundredths)	9.00%
Maturity date of notes receivable received from sale of Midwater Floaters	January 2015
Maximum borrowing amount of working capital loan in connection with sale of Midwater Floaters	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	6	6
ADDCL [Member]
Variable Interest, Carrying Amount [Abstract]
Assets	898	864
Liabilities	356	345
Net carrying amount	542	519
TPDI [Member]
Variable Interest, Carrying Amount [Abstract]
Assets	1,575	1,598
Liabilities	724	763
Net carrying amount	$ 851	$ 835

Income Taxes (Details) (USD $)	3 Months Ended
Income Taxes (Details) (USD $)	Mar. 31, 2011	Mar. 31, 2010	Dec. 31, 2010
Tax rate [Abstract]
Annual effective tax rate (in hundredths)	19.30%	15.20%
Deferred taxes [Abstract]
Valuation allowance for non-current deferred tax assets	$ 94,000,000		$ 94,000,000
Unrecognized tax benefits [Abstract]
Unrecognized tax benefits, excluding interest and penalties	501,000,000		485,000,000
Interest and penalties	244,000,000		235,000,000
Unrecognized tax benefits, including interest and penalties	745,000,000		720,000,000
Tax returns [Abstract]
Maximum number of years agreed to extensions beyond the statute of limitations (in years)	16 Y
Minimum range tax returns are subject to examination (in years)	3 Y
Maximum range tax returns are subject to examination (in years)	6 Y
Tax investigations [Abstract]
2004 and 2005 transfer pricing adjustment	79,000,000
2006 and 2007 income tax adjustments	278,000,000
2006 through 2009 restructuring transactions tax adjustments	295,000,000
2006 through 2009 withholding and other tax adjustments	166,000,000
Assessed penalties associated with the various adjustments	92,000,000
Norway tax assessment due to restructuring transactions	283,000,000
Norway tax assessment due to migration of subsidiary	124,000,000
Norway tax assessment due 2001 dividend payment	75,000,000
Norway tax assessment due foreign exchange deductions	8,000,000
Norway tax financial security	1,100,000,000
Percentage of penalties to be assessed by Norway tax authorities (in hundredths)	60.00%
Brazil tax assessment for income tax returns 2000 to 2004	119,000,000
Percentage of penalties to be assessed by Brazil tax authorities (in hundredths)	75.00%
Brazil tax assessment penalty	89,000,000
Brazil tax assessment interest	$ 144,000,000

Discontinued Operations (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended			3 Months Ended
	Mar. 31, 2011	Mar. 31, 2010	Mar. 31, 2011 Challenger Minerals [Member]	Mar. 31, 2011 Caspian Sea Operations [Member]	Dec. 31, 2010 Caspian Sea Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Period in which we expect the disposal of the assets to be completed			12M
Proceeds from sale of Trident 20	$ 259	$ 0		$ 259
Gain on disposal of the discontinued operations	173	0		173
Gain on disposal of the discontinued operations per diluted share				$ 0.54
Maximum period agreed to continue operating Trident20 under bareboat charter				12M
Assets [Abstract]
Oil and gas properties, net				56	0
Other related assets				13	0
Assets held for sale				69	0
Accounts receivable				17	22
Other assets				13	17
Other current assets				30	39
Rig and related equipment, net				0	86
Oil and gas properties, net				0	53
Other assets				0	139
Liabilities [Abstract]
Accounts payable				19	15
Other liabilities				28	13
Other current liabilities				47	28
Asset retirement obligation				0	9
Deferred taxes				0	19
Other long-term liabilities				0	28
Results of operations [Abstract]
Operating revenues	26	23
Costs and expenses	23	39
Income (loss) from discontinued operations before income tax expense	3	(16)
Income tax benefit	0	18
Gain on disposal of discontinued operations	173	0		173
Income (loss) from discontinued operations, net of tax	$ 176	$ 2

Earnings Per Share (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2011	Mar. 31, 2010
Numerator for earnings per share, basic [Abstract]
Income from continuing operations attributable to controlling interest	$ 134	$ 675
Undistributed earnings allocable to participating securities	(1)	(4)
Income from continuing operations available to shareholders	133	671
Denominator for earnings per share, basic [Abstract]
Weighted-average shares outstanding (in shares)	319	321
Weighted-average shares for per share calculation (in shares)	319	321
Per share earnings from continuing operations, basic (in dollars per share)	$ 0.42	$ 2.09
Numerator for earnings per share, diluted [Abstract]
Income from continuing operations attributable to controlling interest	134	675
Undistributed earnings allocable to participating securities	(1)	(4)
Income from continuing operations available to shareholders	$ 133	$ 671
Denominator for earnings per share, diluted [Abstract]
Weighted-average shares outstanding (in shares)	319	321
Effect of stock options and other share-based awards (in shares)	1	1
Weighted-average shares for per share calculation (in shares)	320	322
Per share earnings from continuing operations, diluted (in dollars per share)	$ 0.42	$ 2.08
Antidilutive securities excluded from computation of earnings per share [Abstract]
Antidilutive share-based awards excluded from the calculation of earnings per share (in shares)	1.2	1.1
1.625% Series A Convertible Senior Notes, stated interest rate (in hundredths)	1.625%
1.50% Series B Convertible Senior Notes, stated interest rate (in hundredths)	1.50%
1.50% Series C Convertible Senior Notes, stated interest rate (in hundredths)	1.50%

Drilling Fleet (Details) (USD $)

3 Months Ended

12 Months Ended

15 Months Ended

3 Months Ended

12 Months Ended

15 Months Ended

3 Months Ended

12 Months Ended

15 Months Ended

3 Months Ended

12 Months Ended

15 Months Ended

3 Months Ended

12 Months Ended

15 Months Ended

3 Months Ended

12 Months Ended

15 Months Ended

3 Months Ended

12 Months Ended

15 Months Ended

3 Months Ended

12 Months Ended

15 Months Ended

3 Months Ended

12 Months Ended

15 Months Ended

3 Months Ended

12 Months Ended

15 Months Ended

3 Months Ended

12 Months Ended

15 Months Ended

Mar. 31, 2011

Mar. 31, 2010

Dec. 31, 2010

Mar. 31, 2011

Sale of Trident 20 and Transocean Mercury [Member]

Mar. 31, 2010

Sale of Two Midwater Floaters [Member]

Mar. 31, 2011

Held for sale GSF Britannia [Member]

Dec. 31, 2010

Held for sale Transocean Mercury [Member]

Mar. 31, 2011

ADDCL [Member]

Mar. 31, 2011

TPDI [Member]

Mar. 31, 2011

Discoverer India [Member]

Dec. 31, 2010

Discoverer India [Member]

Mar. 31, 2011

Discoverer India [Member]

Mar. 31, 2011

Deepwater Champion [Member]

Dec. 31, 2010

Deepwater Champion [Member]

Mar. 31, 2011

Deepwater Champion [Member]

Nov. 30, 2007

Deepwater Champion [Member]

Mar. 31, 2011

Discoverer Luanda [Member]

Dec. 31, 2010

Discoverer Luanda [Member]

Mar. 31, 2011

Discoverer Luanda [Member]

Mar. 31, 2011

Discoverer Inspiration [Member]

Dec. 31, 2010

Discoverer Inspiration [Member]

Mar. 31, 2011

Discoverer Inspiration [Member]

Mar. 31, 2011

Dhirubhai Deepwater Kg 2 [Member]

Dec. 31, 2010

Dhirubhai Deepwater Kg 2 [Member]

Mar. 31, 2011

Dhirubhai Deepwater Kg 2 [Member]

Mar. 31, 2011

Transocean Honor [Member]

Dec. 31, 2010

Transocean Honor [Member]

Mar. 31, 2011

Transocean Honor [Member]

Nov. 30, 2010

Transocean Honor [Member]

Mar. 31, 2011

High-Specification Jackup TBN1 [Member]

Dec. 31, 2010

High-Specification Jackup TBN1 [Member]

Mar. 31, 2011

High-Specification Jackup TBN1 [Member]

Mar. 31, 2011

High-Specification Jackup TBN2 [Member] [Member]

Dec. 31, 2010

High-Specification Jackup TBN2 [Member] [Member]

Mar. 31, 2011

High-Specification Jackup TBN2 [Member] [Member]

Mar. 31, 2011

Capitalized Interest [Member]

Dec. 31, 2010

Capitalized Interest [Member]

Mar. 31, 2011

Capitalized Interest [Member]

Mar. 31, 2011

Mobilization Costs [Member]

Dec. 31, 2010

Mobilization Costs [Member]

Mar. 31, 2011

Mobilization Costs [Member]

Drilling Fleet [Abstract]

Construction work in progress, recorded in property and equipment

$ 1,500,000,000

Actual Capital Expenditures And Other Capital Additions Including Capitalized Interest [Line Items]

Capital expenditures and other capital additions, including capitalized interest costs

126,000,000

4,030,000,000

4,156,000,000

^[1]

744,000,000

^[1]

744,000,000

^[1]

23,000,000

^[2]

733,000,000

^[2]

756,000,000

^[2]

8,000,000

^[1],[3]

709,000,000

^[1],[3]

717,000,000

^[1],[3]

^[1]

679,000,000

^[1]

679,000,000

^[1]

^[1],[4]

677,000,000

^[1],[4]

677,000,000

^[1],[4]

47,000,000

^[5]

97,000,000

^[5]

144,000,000

^[5]

10,000,000

^[6]

9,000,000

^[6]

19,000,000

^[6]

10,000,000

^[6]

9,000,000

^[6]

19,000,000

^[6]

15,000,000

273,000,000

288,000,000

13,000,000

100,000,000

113,000,000

Initial installment payment

97,000,000

9,000,000

Initial investment in construction project

109,000,000

195,000,000

186,000,000

Number of high-specification jackups purchased and under construction

Costs as a percentage of total expenditures incurred since inception (in hundredths)

100.00%

Schedule of Variable Interest Entities [Line Items]

Ownership interest in affiliate (in hundredths)

65.00%

50.00%

Noncontrolling owner's ownership interest in affiliate (in hundredths)

50.00%

35.00%

50.00%

Dispositions [Abstract]

Net cash proceeds from sale of assets

13,000,000

41,000,000

10,000,000

38,000,000

Gain (loss) on the sale of assets

8,000,000

(14,000,000)

9,000,000

(15,000,000)

Gain (loss) on the sale of assets per diluted share (in dollars per share)

$ 0.03

$ (0.05)

Recognized gain (loss) on disposal of unrelated assets

(1,000,000)

1,000,000

Number of Midwater Floaters sold

Number of notes receivable provided as non-cash proceeds from sale of assets

Non-cash proceeds in the form of notes receivable from sale of assets

165,000,000

Assets held for sale [Abstract]

Assets held for sale

$ 77,000,000

$ 0

$ 77,000,000

$ 8,000,000

$ 1,000,000

[1]	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 March 31, 2011.
[2]	These costs include our initial investment in Deepwater Champion of $109 million, representing the estimated fair value of the rig at the time of our merger with GlobalSantaFe Corporation ("GlobalSantaFe") in November 2007.
[3]	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 ADDCL, and Angco Cayman Limited holds the remaining 35 percent interest.
[4]	The costs for 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 TPDI, and Quantum Pacific Management Limited, a Cypriot company and successor in interest to Pacific Drilling Limited ("Quantum") holds the remaining 50 percent interest.
[5]	In November 2010, we made an initial installment payment of $97 million to purchase a PPL Pacific Class 400 design jackup, to be named Transocean Honor, for $195 million. The High-Specification Jackup is under construction at PPL Shipyard Pte Ltd. in Singapore and is expected for delivery in the fourth quarter of 2011.
[6]	In December 2010, we made initial installment payments of $9 million each to purchase two Keppel FELS Super B class design jackups for $186 million each. The two High-Specification Jackups are under construction at Keppel FELS's yard in Singapore and are expected for delivery in the first quarter of 2013.

Debt (Details) (USD $)

3 Months Ended

12 Months Ended

Mar. 31, 2011

Mar. 31, 2010

Dec. 31, 2010

Derivatives and Hedging (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended						3 Months Ended
	Mar. 31, 2011 Interest Expense [Member]	Mar. 31, 2010 Interest Expense [Member]	Mar. 31, 2011 Other Assets [Member]	Dec. 31, 2010 Other Assets [Member]	Mar. 31, 2011 Other Long Term Liabilities [Member]	Dec. 31, 2010 Other Long Term Liabilities [Member]	Mar. 31, 2011 Interest Rate Swap 1 [Member]	Mar. 31, 2011 Interest Rate Swap 2 [Member]	Mar. 31, 2011 Interest Rate Swap 3 [Member]
Derivative [Line Items]
Derivative, underlying risk							interest rate	interest rate	interest rate
Derivative, hedge designation							cash flow	fair value	fair value
Derivative, description of hedged item							borrowings under the TPDI Credit Facilities	5.25% Senior Notes	5.00% Notes
Derivative, notional amount							$ 1,100	$ 500	$ 250
Notional value of interest rate swaps attributable to subsidiary							525
Derivative, average variable interest rate (in hundredths)							0.30%	3.50%	3.50%
Derivative, weighted-average fixed interest rate (in hundredths)							2.30%	5.25%	5.00%
Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Line Items]
Interest rate cash flow hedge derivative at fair value, net					10	13
Interest rate fair value hedge derivative at fair value, net			15	17
Derivative Instruments, Gain (Loss) by Hedging Relationship, by Income Statement Location, by Derivative Instrument Risk [Line Items]
Gain (loss) on interest rate cash flow hedge ineffectiveness	$ (1)	$ (1)

Postemployment Benefit Plans (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2011	Mar. 31, 2010
Net periodic benefit costs, before tax and funding contributions [Abstract]
Service cost	$ 16	$ 16
Interest cost	20	20
Expected return on plan assets	(21)	(19)
Settlements and curtailments	0	1
Actuarial losses, net	6	4
Prior service cost, net	0	(1)
Net periodic benefit costs	21	21
Funding contributions	21	8
U.S. Plans [Member]
Net periodic benefit costs, before tax and funding contributions [Abstract]
Service cost	11	10
Interest cost	14	14
Expected return on plan assets	(16)	(14)
Settlements and curtailments	0	0
Actuarial losses, net	6	3
Prior service cost, net	0	0
Net periodic benefit costs	15	13
Funding contributions	13	2
Non-U.S. Plans [Member]
Net periodic benefit costs, before tax and funding contributions [Abstract]
Service cost	5	6
Interest cost	5	5
Expected return on plan assets	(5)	(5)
Settlements and curtailments	0	1
Actuarial losses, net	0	1
Prior service cost, net	0	0
Net periodic benefit costs	5	8
Funding contributions	7	4
OPEB Plans [Member]
Net periodic benefit costs, before tax and funding contributions [Abstract]
Service cost	0	0
Interest cost	1	1
Expected return on plan assets	0	0
Settlements and curtailments	0	0
Actuarial losses, net	0	0
Prior service cost, net	0	(1)
Net periodic benefit costs	1	0
Funding contributions	$ 1	$ 2

Contingencies (Details) (USD $)	3 Months Ended
Contingencies (Details) (USD $)	Mar. 31, 2011	Jan. 27, 2011	Dec. 31, 2010	Jun. 30, 2010	May 05, 2010	Apr. 22, 2010	Mar. 31, 2010
Macondo well incident [Abstract]
Number of persons declared dead						11
Number of miles Deepwater Horizon was off coast of Louisiana						41
Liability recorded based on probable losses related to the rig explosion and fire incident	$ 170,000,000
Portion of liability related to the rig explosion and fire incident recoverable from insurance and recognized as a receivable	130,000,000
Number of subsidiaries entities named in numerous complaints that allege wrongful death and other personal injuries	we and one or more of our subsidiaries
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	31
Number of individual complaints filed alleging, among other things, economic losses as a result of environmental pollution arising out of the Macondo well incident	61
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	179
Number of federal securities law class actions filed	2
Number of federal securities law class actions filed which generally allege violations of Section 10(b) of the Securities Exchange Act of 1934	2
Number of shareholder derivative suits filed				2
Number of Gulf Coast states Attorneys General seeking recovery of clean up costs and damages					5
Number of Atlantic Coast states Attorneys General wanting assurances of financial responsibility for potential damages				11
Percentage of asset value covered by wreck removal insurance (in hundredths)	25.00%
Asset value covered by wreck removal insurance	140,000,000
Amount agreed to indemnify and defend operator of rig	15,000,000
Asbestos litigation [Abstract]
Number of complaints filed in 2004 in Mississippi regarding asbestos litigation	21
Number of plaintiffs covered by complaints filed in 2004 in Mississippi regarding asbestos litigation	769
Number of subsidiaries named as a direct defendant in amended asbestos complaints	1
Number of cases filed under amended complaint in Mississippi regarding asbestos litigation	7
Number of additional cases in which there may be an indirect interest regarding asbestos litigation	12
Number of cases from original asbestos claim in 2004 that went to trial in 2009 against unaffiliated defendant companies	2
Number of cases from original asbestos claim in 2004 that went to trial in 2009 that received verdict in favor of plaintiff	1
Number of cases from original asbestos claim in 2004 that went to trial in 2009 that received verdict in favor of defendant	second case
Additional trials in 2010	2
Substantial verdict for the plaintiff	1
Complete verdict for the defendants	1
Number of subsidiaries involved in lawsuits arising from design, construction and refurbishment of major industrial complexes	1
Number of lawsuits alleging personal injury from asbestos exposure for subsidiary involved in design, construction and refurbishment of major industrial complexes	1,028
Estimated number of plaintiffs in lawsuits alleging personal injury from asbestos exposure for subsidiary involved in design, construction and refurbishment of major industrial complexes	2,438
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
Rio de Janeiro Tax Assessment [Abstract]
Tax assessment from state tax authorities of Rio de Janeiro in Brazil	197,000,000
Number of subsidiaries involved in Rio de Janeiro federal tax assessment relating to import license	1
Brazilian import license assessment [Abstract]
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 [Abstract]
Percentage of liability for remediation and related costs from hazardous waste disposal site (in hundredths)	8.00%
Number of subsidiaries ordered by California Regional Water Quality Control Board to develop testing plan for Alhambra, California site	1
Number of subsidiaries likely to be named potentially responsible party by US Environmental Protection Agency for superfund site	one or more
Contamination litigation [Abstract]
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
Amount claimed by defendants' experts as required remediation costs for property contamination in Louisiana	2,500,000
Number of additional subsidiaries plaintiff attempted to add as defendant for lawsuit alleging property contamination in Louisiana	2
Amount of settlement by codefendant for property contamination in Louisiana	20,000,000
Retained risk [Abstract]
Aggregate value of drilling rig fleet	38,500,000,000
Per occurrence insurance deductible on hull and machinery	125,000,000
Maximum aggregate insurance deductible on hull and machinery per year	250,000,000
Percentage of asset value covered by damage mitigation insurance (in hundredths)	25.00%
Shared deductible in the event of a total loss or a constructive total loss of a drilling unit	0
Commercial market excess liability coverage	950,000,000
Per occurrence deductible on crew personal injury liability and collision liability claims	10,000,000
Per occurrence deductible on other third-party non-crew claims	5,000,000
Aggregate per occurrence deductible on other third party non-crew claims	50,000,000
Liability loss limit for commercial market excess liability coverage	1,000,000,000
Additional insurance that covers expenses that would otherwise be assumed by the well owner	100,000,000
Maximum liability amount for well control and redrilling liability related to blowouts	50,000,000
Letters of credit and surety bonds [Abstract]
Letters of credit outstanding	641,000,000		595,000,000
Amount of letter of credit issued on behalf of TPDI							60,000,000
Number of subsidiaries that established the letter of credit on behalf of TPDI							1
Surety bonds outstanding	$ 24,000,000		$ 27,000,000
Number of insurers which filed pleadings to move lawsuit to United States District Court		1
Term of maximum policy period for the commercial market and captive insurance policies	12M
Term of minimum policy period for the commercial market and captive insurance policies	11M

Shareholders' Equity (Details) Share data in Millions, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2008	Mar. 31, 2011 USD ($)	Mar. 31, 2011 CHF	Feb. 11, 2011 USD ($)	Dec. 31, 2010	Aug. 13, 2010	May 31, 2010 USD ($)	May 31, 2010 CHF
Distribution [Abstract]
Cash distribution approved in the form of a par value reduction (in CHF or dollars per share)							$ 3.74	3.44
Share repurchase USD exchange rate		$ 1.00
Share repurchase CHF exchange rate			0.92
Number of planned partial par value reductions previously approved by shareholders						4
Proposed U.S. dollar-denominated dividend				$ 1,000,000,000
Number of quarterly installments				4
Shares held by subsidiary [Abstract]
Number of issued shares held by subsidiary (in shares)	16
Number of shares held by subsidiary (in shares)		13	13		13

Fair Value of Financial Instruments (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2011	Dec. 31, 2010
Carrying amount [Member]
Derivative instruments [Abstract]
Derivative financial instruments, assets	$ 15	$ 17
Derivative financial instruments, liabilities	10	13
Financial Instruments, Financial Assets, Balance Sheet Groupings [Abstract]
Notes receivable	116	115
Notes receivable, current	6	4
Notes receivable, noncurrent	110	111
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
Long-term debt, including current maturities	10,326	10,271
Long-term debt of consolidated variable interest entities, including current maturities	915	950
Fair value [Member]
Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract]
TPDI Notes and Overseas Drilling Limited Loan Facility	153	158
Long-term debt, including current maturities	10,771	10,562
Long-term debt of consolidated variable interest entities, including current maturities	$ 925	$ 964

Subsequent Events (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2011
Debt repayments [Member]
Subsequent Event [Line Items]
Date of subsequent event	Mar. 31, 2011
Description of subsequent event	Aggregate cash payment made to redeem the remaining aggregate principal amount of the 6.625 % Notes due April 2011.
Debt instrument interest rated stated percentage (in hundredths)	6.625%
Debt instrument maturity date	April 15, 2011
Amount related to subsequent event	$ 166
Macondo Well [Member] \| Anadarko Petroleum Corporation [Member]
Subsequent Event [Line Items]
Date of subsequent event	Apr. 30, 2011
Description of subsequent event	In April 2011, several defendants in the Macondo litigation before the MDL filed cross-claims and/or third-party claims against Transocean entities and other defendants.
Macondo well incident
Non-operating interest in the Macondo well (in hundredths)	25.00%
Macondo Well [Member] \| MOEX Offshore 2007 LLC [Member]
Subsequent Event [Line Items]
Date of subsequent event	Apr. 30, 2011
Description of subsequent event	In April 2011, several defendants in the Macondo litigation before the MDL filed cross-claims and/or third-party claims against Transocean entities and other defendants.
Macondo well incident
Non-operating interest in the Macondo well (in hundredths)	10.00%