CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2010	Mar. 31, 2009
Operating revenues
Contract drilling revenues	$ 2,441	$ 2,834
Contract drilling intangible revenues	33	104
Other revenues	128	180
Operating revenues	2,602	3,118
Costs and expenses
Operating and maintenance	1,196	1,171
Depreciation, depletion and amortization	401	355
General and administrative	63	56
Costs and expenses	1,660	1,582
Loss on impairment	(2)	(221)
Gain (loss) on disposal of assets, net	(14)	4
Operating income	926	1,319
Other income (expense), net
Interest income	5	1
Interest expense, net of amounts capitalized	(132)	(136)
Other, net	15	6
Total other income (expense), net	(112)	(129)
Income before income tax expense	814	1,190
Income tax expense	129	251
Net income	685	939
Net income (loss) attributable to noncontrolling interest	8	(3)
Net income attributable to controlling interest	$ 677	$ 942
Earnings per share
Basic	$ 2.10	$ 2.94
Diluted	$ 2.09	$ 2.93
Weighted average shares outstanding
Basic	321	319
Diluted	322	320

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2010	Mar. 31, 2009
Statement of Income and Comprehensive Income [Abstract]
Net income	$ 685	$ 939
Other comprehensive loss before income taxes
Unrecognized components of net periodic benefit cost	(10)	(39)
Recognized components of net periodic benefit cost	6	4
Unrealized loss on derivative instruments	(6)	(1)
Other comprehensive loss before income taxes	(10)	(36)
Income taxes related to other comprehensive loss	0	8
Other comprehensive loss, net of income taxes	(10)	(28)
Total comprehensive income	675	911
Total comprehensive income (loss) attributable to noncontrolling interest	1	(3)
Total comprehensive income attributable to controlling interest	$ 674	$ 914

CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2010	Dec. 31, 2009
Assets
Cash and cash equivalents	$ 1,586	$ 1,130
Accounts receivable, net of allowance for doubtful accounts of $41 and $65 at March 31, 2010 and December 31, 2009, respectively	2,285	2,385
Materials and supplies, net of allowance for obsolescence of $64 and $66 at March 31, 2010 and December 31, 2009, respectively	464	462
Deferred income taxes, net	113	104
Assets held for sale	0	186
Other current assets	263	209
Total current assets	4,711	4,476
Property and equipment	27,604	27,383
Property and equipment of consolidated variable interest entities	2,149	1,968
Less accumulated depreciation	6,728	6,333
Property and equipment, net	23,025	23,018
Goodwill	8,132	8,134
Other assets	970	808
Total assets	36,838	36,436
Liabilities and equity
Accounts payable	746	780
Accrued income taxes	240	240
Debt due within one year	1,447	1,568
Debt of consolidated variable interest entities due within one year	82	300
Other current liabilities	787	730
Total current liabilities	3,302	3,618
Long-term debt	8,990	8,966
Long-term debt of consolidated variable interest entities	920	883
Deferred income taxes, net	713	726
Other long-term liabilities	1,707	1,684
Total long-term liabilities	12,330	12,259
Commitments and contingencies
Shares, CHF 15.00 par value, 502,852,947 authorized, 167,617,649 conditionally authorized, 335,235,298 issued at March 31, 2010 and December 31, 2009; 320,950,624 and 321,223,882 outstanding at March 31, 2010 and December 31, 2009, respectively	4,478	4,472
Additional paid-in capital	7,433	7,407
Retained earnings	9,685	9,008
Accumulated other comprehensive loss	(338)	(335)
Treasury shares, at cost, 717,000 and none held at March 31, 2010 and December 31, 2009, respectively	(60)	0
Total controlling interest shareholders' equity	21,198	20,552
Noncontrolling interest	8	7
Total equity	21,206	20,559
Total liabilities and equity	$ 36,838	$ 36,436

PARENTHETICAL DATA TO THE CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Millions, except Share data, unless otherwise specified	Mar. 31, 2010	Dec. 31, 2009
Assets
Accounts receivable, allowance for doubtful accounts	$ 41	$ 65
Materials and supplies, allowance for obsolescence	$ 64	$ 66
Liabilities and equity
Shares, par value CHF per share	$ 15	$ 15
Shares, authorized	502,852,947	502,852,947
Shares, conditionally authorized	167,617,649	167,617,649
Shares, issued	335,235,298	335,235,298
Shares, outstanding	320,950,624	321,223,882
Treasury shares, at cost	717,000	0

CONDENSED CONSOLIDATED STATEMENTS OF EQUITY (Unaudited) (USD $) In Millions	Total	Total controlling interest shareholders' equity [Member]	Shares	Additional paid-in capital	Retained earnings	Accumulated other comprehensive loss	Treasury shares, at cost	Total noncontrolling interest
Balance, beginning of period at Dec. 31, 2008	$ 17,167	$ 17,164	$ 4,444	$ 7,313	$ 5,827	$ (420)	$ 0	$ 3
Balance, beginning of period (in shares) at Dec. 31, 2008			319
Other comprehensive loss attributable to controlling interest	(28)					(28)
Net income attributable to controlling interest	939				942
Total comprehensive income attributable to controlling interest	911	914						(3)
Share-based compensation expense	19	19		19
Issuance of shares under share-based compensation plans	17	17	11	6
Issuance of shares under share-based compensation plans (in shares)			1
Purchases of treasury shares	0	0					0
Purchases of treasury shares (in shares)			0
Repurchase of convertible notes	6	6		6
Other, net	0	0		0
Balance, end of period at Mar. 31, 2009	18,120	18,120	4,455	7,344	6,769	(448)	0	0
Balance Balance, end of period (in shares) at Mar. 31, 2009			320
Balance, beginning of period at Dec. 31, 2009	20,559	20,552	4,472	7,407	9,008	(335)	0	7
Balance, beginning of period (in shares) at Dec. 31, 2009			321
Other comprehensive loss attributable to controlling interest	(10)					(3)
Net income attributable to controlling interest	685				677
Total comprehensive income attributable to controlling interest	675	674						1
Share-based compensation expense	35	35		35
Issuance of shares under share-based compensation plans	(4)	(4)	6	(10)
Issuance of shares under share-based compensation plans (in shares)			1
Purchases of treasury shares	(60)	(60)					(60)
Purchases of treasury shares (in shares)			(1)
Repurchase of convertible notes	0	0		0
Other, net	1	1		1
Balance, end of period at Mar. 31, 2010	$ 21,206	$ 21,198	$ 4,478	$ 7,433	$ 9,685	$ (338)	$ (60)	$ 8
Balance Balance, end of period (in shares) at Mar. 31, 2010			321

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2010	Mar. 31, 2009
Cash flows from operating activities
Net income	$ 685	$ 939
Adjustments to reconcile net income to net cash provided by operating activities:
Amortization of drilling contract intangibles	(33)	(104)
Depreciation, depletion and amortization	401	355
Share-based compensation expense	35	19
(Gain) loss on disposal of assets, net	14	(4)
Loss on impairment	2	221
Amortization of debt issue costs, discounts and premiums, net	49	52
Deferred income taxes	(22)	6
Other, net	3	11
Deferred revenue, net	151	(6)
Deferred expenses, net	(14)	2
Changes in operating assets and liabilities	(99)	(50)
Net cash provided by operating activities	1,172	1,441
Cash flows from investing activities
Capital expenditures	(379)	(708)
Proceeds from disposal of assets, net	41	8
Proceeds from distributions from short-term investments	5	221
Joint ventures and other investments, net	10	0
Net cash used in investing activities	(323)	(479)
Cash flows from financing activities
Change in short-term borrowings, net	(131)	(24)
Proceeds from debt	54	88
Repayments of debt	(253)	(600)
Repurchases of convertible senior notes	0	(102)
Purchases of treasury shares	(60)	0
Proceeds from (taxes paid for) share-based compensation plans, net	(4)	17
Other, net	1	(2)
Net cash used in financing activities	(393)	(623)
Net increase in cash and cash equivalents	456	339
Cash and cash equivalents at beginning of period	1,130	963
Cash and cash equivalents at end of period	$ 1,586	$ 1,302

Significant Accounting Policies	3 Months Ended
Significant Accounting Policies	Mar. 31, 2010
Notes To Financial Statements [Abstract]
Significant Accounting Policies	Note 2—Significant Accounting Policies Basis of presentation—Our accompanying condensed consolidated financial statements have been prepared without audit 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 identified. Operating results for the three months ended March 31, 2010 are not necessarily indicative of the results that may be expected for the year ending December 31, 2010 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 included in our annual report on Form 10-K for the year ended December 31, 2009. Accounting estimates—The preparation of financial statements in accordance with accounting principles generally accepted in the U.S. requires us to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues and expenses and the disclosures of contingent assets and liabilities. On an ongoing basis, we evaluate our estimates and assumptions, including those related to our allowance for doubtful accounts, materials and supplies obsolescence, property and equipment, investments, notes receivable, goodwill and other intangible assets, income taxes, share-based compensation, defined benefit pension plans and other postretirement benefits and contingencies. We base our estimates and assumptions on historical experience and on various other factors we believe are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying amounts of assets and liabilities that are not readily apparent from other sources. Actual results could differ from such estimates. Fair value measurements—We estimate fair value at a price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants in the principal market for the asset or liability. Our valuation techniques require inputs that we categorize using a three-level hierarchy 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 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 those investments that meet the criteria of a variable interest entity where we are deemed to be the primary beneficiary for accounting purposes and for entities in which we have a majority voting interest. Intercompany transactions and accounts are eliminated in consolidation. For investments in joint ventures and other entities that do not meet the criteria of a variable interest entity or where we are not deemed to be the primary beneficiary for accounting purposes of those entities that meet the variable interest entity criteria, we use the equity method of accounting if we have the ability to exercise significant influence over the unconsolidated affiliate. We use the cost method of accounting for investments in joint ventures and other entities if we do not have the ability to exercise significant influence over the unconsolidated affiliate. See Note 4—Variable Interest Entities. Share-based compensation—Share-based compensation expense was $35 million ($33 million, or $0.10 per diluted share, net of tax) and $19 million ($17 million, or $0.05 per diluted share, net of tax) for the three months ended March 31, 2010 and March 31, 2009, respectively. Pension and other postretirement benefits—Pension and other postretirement benefit plan obligations represented a total liability of $525 million and $514 million at March 31, 2010 and December 31, 2009, respectively. Net periodic benefit costs were $21 million and $22 million for the three months ended March 31, 2010 and March 31, 2009, respectively. See Note 11—Postemployment Benefit Plans. Capitalized interest—We capitalize interest costs for qualifying construction and upgrade projects. We capitalized interest costs on construction work in progress of $28 million and $46 million for the three months ended March 31, 2010 and March 31, 2009, respectively. Reclassifications—We have made certain reclassifications to prior period amounts to conform with the current period’s presentation. These 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.

New Accounting Pronouncements	3 Months Ended
New Accounting Pronouncements	Mar. 31, 2010
Notes To Financial Statements [Abstract]
New Accounting Pronouncements	Note 3—New Accounting Pronouncements Recently Adopted Accounting Standards Consolidation—Effective January 1, 2010, we adopted the accounting standards update that requires enhanced transparency of our involvement with variable interest entities, which (a) amends certain guidance for determining whether an enterprise is a variable interest entity, (b) requires a qualitative rather than a quantitative analysis to determine the primary beneficiary, and (c) requires continuous assessments of whether an enterprise is the primary beneficiary of a variable interest entity. We evaluated these requirements, particularly with regard to our interests in Transocean Pacific Drilling Inc. (“TPDI”) and Angola Deepwater Drilling Company Limited (“ADDCL”) and our adoption did not have a material effect on our condensed consolidated statement of financial position, results of operations or cash flows. See Note 4—Variable Interest Entities. Fair value measurements and disclosures—Effective January 1, 2010, we adopted the effective provisions of the accounting standards update that clarifies existing disclosure requirements and introduces additional disclosure requirements for fair value measurements. The update requires entities to disclose the amounts of and reasons for significant transfers between Level 1 and Level 2, the reasons for any transfers into or out of Level 3, and information about recurring Level 3 measurements of purchases, sales, issuances and settlements on a gross basis. The update also clarifies that entities must provide (a) fair value measurement disclosures for each class of assets and liabilities and (b) information about both the valuation techniques and inputs used in estimating Level 2 and Level 3 fair value measurements. We have applied the effective provisions of this accounting standards update in preparing the disclosures in our notes to condensed consolidated financial statements and our adoption did not have a material effect on such disclosures. See Note 2—Significant Accounting Policies. Subsequent events—Effective for financial statements issued after February 2010, we adopted the accounting standards update regarding subsequent events, which clarifies that SEC filers are not required to disclose the date through which management evaluated subsequent events in the financial statements. Our adoption did not have a material effect on the disclosures contained within our notes to condensed consolidated financial statements. See Note 2—Significant Accounting Policies. Recently Issued Accounting Standards Fair value measurements and disclosures—Effective January 1, 2011, we will adopt the remaining provisions of the accounting standards update that clarifies existing disclosure requirements and introduces additional disclosure requirements for fair value measurements. The update requires entities to separately disclose information about purchases, sales, issuances, and settlements in the reconciliation of recurring Level 3 measurements on a gross basis. The update is effective for interim and annual periods beginning after December 15, 2010. We do not expect that our adoption will have a material effect on the disclosures contained in our notes to consolidated financial statements.

Income Taxes

3 Months Ended

Mar. 31, 2010

Notes To Financial Statements [Abstract]

Income Taxes

Note 6—Income Taxes

Overview—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.

Tax provision—We conduct operations through our various subsidiaries in a number of countries throughout the world, all of which have taxation regimes with varying nominal rates, deductions, credits and other tax attributes. Our provision for income taxes is based on the tax laws and rates applicable in the jurisdictions in which we operate and earn income. Consequently, there is little to no expected relationship between the provision for or benefit from income taxes and income or loss before income taxes.

Our estimated annual effective tax rates for the three months ended March 31, 2010 and March 31, 2009 were 15.0 percent and 15.2 percent, respectively. These rates were based on estimated annual income before income taxes for each period after adjusting for certain items, such as impairment losses and various other discrete items.

We record a valuation allowance for deferred tax assets, including those resulting from net operating losses, when it is more likely than not that we will not realize some or all of the benefit from the deferred tax assets. At March 31, 2010 and December 31, 2009, the valuation allowance for non-current deferred tax assets was $69 million.

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 1999. For the three months ended March 31, 2010 and March 31, 2009, the amount of current tax benefit recognized from the settlement of disputes with tax authorities and from the expiration of statutes of limitations was insignificant.

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, 2010		December 31, 2009
Unrecognized tax benefits, excluding interest and penalties	$	460	$	460
Interest and penalties		202		200
Unrecognized tax benefits, including interest and penalties	$	662	$	660

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 three major jurisdictions for up to 15 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.

Tax positions—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, reducing the total proposed adjustment to 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 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 and we expect the matter to proceed to litigation.

With respect to the 2006 and 2007 U.S. federal income tax returns, we have been notified by the U.S. tax authorities of proposed adjustments related to a series of restructuring transactions that occurred between 2001 and 2004. These restructuring transactions ultimately resulted in the disposition of our interests in our former subsidiary TODCO in 2004 and 2005. The authorities are disputing the amount of capital losses resulting 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 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 proposed net adjustments to our 2006 and 2007 U.S. federal income tax returns total approximately $188 million. We believe an unfavorable outcome on these proposed adjustments could result in a material adverse effect on our consolidated financial position, results of operations or cash flows. We believe that our tax returns are materially correct as filed, and we will vigorously defend against any potential claims.

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 approximately $263 million, plus interest, related to certain restructuring transactions, approximately $115 million, plus interest, related to the migration of a subsidiary that was previously subject to tax in Norway, approximately $69 million, plus interest, related to a 2001 dividend payment, and approximately $8 million, plus interest, related to certain foreign exchange deductions and dividend withholding tax. We have filed or expect to file appeals to all these tax assessments. We may be required to provide some form of financial security, in an amount up to $973 million, 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 all matters. We believe an unfavorable outcome on these matters could result in a material adverse effect on our consolidated financial position, results of operations or cash flows. 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 plan to vigorously contest any assertions by the Norwegian authorities in connection with the various transactions being investigated.

During the three months ended March 31, 2010, our long-term liability for unrecognized tax benefits related to these Norwegian tax issues remained at $181 million due to the accrual of interest being offset by favorable exchange rate fluctuations. 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 financial position or results of operations, although it may have a material adverse effect on our consolidated cash flows.

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 $110 million, plus a 75 percent penalty of $83 million and $99 million of interest through March 31, 2010. We believe an unfavorable outcome on these proposed assessments could result in a material adverse effect on our consolidated financial position, results of operations or cash flows. We believe our returns are materially correct as filed, and we are vigorously contesting these assessments. We filed a protest letter with the Brazilian tax authorities on January 25, 2008, and we are currently engaged in the appeals process.

Drilling Fleet Expansion and Dispositions

3 Months Ended

Mar. 31, 2010

Notes To Financial Statements [Abstract]

Drilling Fleet Expansion and Dispositions

Note 8—Drilling Fleet Expansion and Dispositions

Drilling fleet expansion— Construction work in progress, recorded in property and equipment, was $2.6 billion and $3.7 billion at March 31, 2010 and December 31, 2009, respectively. The following table presents actual capital expenditures and other capital additions, including capitalized interest, for our remaining major construction projects (in millions):

	Three months ended March 31, 2010		Through December 31, 2009		Total costs

Discoverer Luanda (a)	$	145	$	535	$	680
Discoverer India		32		541		573
Deepwater Champion(b)		31		527		558
Dhirubhai Deepwater KG2 (c) (d)		24		641		665
Discoverer Inspiration (c)		9		667		676
Capitalized interest		28		183		211
Mobilization costs		12		19		31
Total	$	281	$	3,113	$	3,394

______________________________

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

(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)	The accumulated construction costs of these rigs are no longer included in construction work in progress, as their construction or conversion projects had been completed as of March 31, 2010.

(d)

The costs for Dhirubhai Deepwater KG2 represent 100 percent of expenditures incurred prior to our investment in the joint venture ($178 million) and 100 percent of expenditures incurred since our investment in the joint venture. TPDI is responsible for these costs. We hold a 50 percent interest in TPDI, and Pacific Drilling Limited holds the remaining 50 percent interest.

During the three months ended March 31, 2010, we acquired GSF Explorer, an asset formerly held under capital lease, in exchange for a cash payment terminating the capital lease obligation in the amount of $15 million. See Note 9—Debt.

Dispositions—During the three months ended March 31, 2010, we completed the sale of two Midwater Floaters, GSF Arctic II and GSF Arctic IV. In connection with the sale, we received net cash proceeds of $38 million and non-cash proceeds in the form of two notes receivable in the aggregate amount of $165 million. The notes receivable, which are secured by the drilling units, have stated interest rates of 9 percent and are payable in scheduled quarterly installments of principal and interest through maturity in January 2015. We estimated the fair values of the notes receivable based on unobservable inputs that require significant judgment, for which there is little or no market data. We continue to operate GSF Arctic IV under a short-term bareboat charter with the new owner of the vessel through October 2010. As a result of the sale, we recognized a loss on disposal of assets for the three months ended March 31, 2010 in the amount of $15 million.

For the three months ended March 31, 2010 and March 31, 2009, gains on disposal of other assets were $1 million and $4 million, respectively. See Note 15—Subsequent Events.

Debt

3 Months Ended

Mar. 31, 2010

Notes To Financial Statements [Abstract]

Debt

Note 9—Debt

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

	March 31, 2010		December 31, 2009

ODL Loan Facility	$	10	$	10
Commercial paper program (a)		150		281
6.625% Notes due April 2011 (a)		169		170
5% Notes due February 2013		250		247
5.25% Senior Notes due March 2013 (a)		502		496
6.00% Senior Notes due March 2018 (a)		997		997
7.375% Senior Notes due April 2018 (a)		247		247
Capital lease obligation due July 2026		—		15
8% Debentures due April 2027 (a)		57		57
7.45% Notes due April 2027 (a)		96		96
7% Senior Notes due June 2028		312		313
Capital lease contract due August 2029		707		711
7.5% Notes due April 2031 (a)		598		598
1.625% Series A Convertible Senior Notes due December 2037 (a)		1,271		1,261
1.50% Series B Convertible Senior Notes due December 2037 (a)		2,075		2,057
1.50% Series C Convertible Senior Notes due December 2037 (a)		1,997		1,979
6.80% Senior Notes due March 2038 (a)		999		999
Total debt		10,437		10,534
Less debt due within one year
ODL Loan Facility		10		10
Commercial paper program (a)		150		281
Capital lease contract due August 2029		16		16
1.625% Series A Convertible Senior Notes due December 2037 (a)		1,271		1,261
Total debt due within one year		1,447		1,568
Total long-term debt	$	8,990	$	8,966

______________________________

(a)

Transocean Inc., a wholly 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 subsidiaries not owned indirectly through Transocean Inc. are minor. Transocean Ltd. is not subject to any significant restrictions on its ability to obtain funds from its consolidated subsidiaries or entities accounted for under the equity method by dividends, loans or return of capital distributions.

The debt of consolidated variable interest entities after the elimination of intercompany balances was comprised of the following (in millions):

	March 31, 2010		December 31, 2009

TPDI Credit Facilities due March 2015	$	613	$	581
ADDCL Credit Facilities due June 2017		241		454
TPDI Notes due October 2019		148		148
Total debt of consolidated variable interest entities		1,002		1,183
Less debt of consolidated variable interest entities due within one year
TPDI Credit Facilities due March 2015		70		52
ADDCL Credit Facilities due June 2017		12		248
Total debt of consolidated variable interest entities due within one year		82		300
Total long-term debt of consolidated variable interest entities	$	920	$	883

Scheduled maturities—In preparing the scheduled maturities of our debt, we assume the bondholders will exercise their options to require us to repurchase the 1.625% Series A, 1.50% Series B and 1.50% Series C Convertible Senior Notes (collectively, the “Convertible Senior Notes”) in December 2010, 2011 and 2012, respectively. At March 31, 2010, the scheduled maturities of our debt were as follows (in millions):

	Transocean Ltd.			Consolidated variable interest entities		Consolidated total
Twelve months ending March 31,
2011	$	1,475		$	82	$	1,557
2012		2,383			96		2,479
2013		2,969			98		3,067
2014		20			99		119
2015		22			364		386
Thereafter		3,915			263		4,178
Total debt, excluding unamortized discounts, premiums and fair value adjustments		10,784			1,002		11,786
Total unamortized discounts, premiums and fair value adjustments		(347	)		—		(347	)
Total debt	$	10,437		$	1,002	$	11,439

Commercial paper program—We maintain a commercial paper 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. At March 31, 2010, $150 million in commercial paper was outstanding at a weighted-average interest rate of 0.3 percent.

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 and was 0.15 percent at March 31, 2010. At March 31, 2010, we had $81 million in letters of credit issued and outstanding and 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 secured term loan with an aggregate commitment of $595 million. At March 31, 2010, $1.2 billion was outstanding under the TPDI Credit Facilities, of which $595 million was due to one of our subsidiaries and was eliminated in consolidation. The weighted-average interest rate on March 31, 2010 was 3.9 percent. See Note 10—Derivatives and Hedging.

TPDI Notes—TPDI has issued the TPDI Notes which have maturities through October 2019. At March 31, 2010, the aggregate outstanding principal amount was $296 million, $148 million of which was due to one of our subsidiaries and has been eliminated in consolidation. The weighted-average interest rate on March 31, 2010 was 2.4 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, Tranche B and Tranche C for $215 million, $270 million and $399 million, respectively, which was established to finance the construction of and is secured by Discoverer Luanda. Tranche A and Tranche B are provided by external lenders. One of our subsidiaries has agreed to provide financing for Tranche C, and another subsidiary has agreed to provide financial security for the borrowings under Tranche A and Tranche B until the first well commencement date. During the three months ended March 31, 2010, ADDCL repaid borrowings under Tranche B using borrowings under Tranche C, which was eliminated in consolidation. At March 31, 2010, $215 million was outstanding under Tranche A at a weighted-average interest rate of 0.7 percent.

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, 2010, $75 million was outstanding under the ADDCL Secondary Loan Facility, of which $49 million was provided by one of our subsidiaries and has been eliminated in consolidation. The weighted-average interest rate on March 31, 2010 was 3.4 percent.

Capital lease obligation—During the three months ended March 31, 2010, we acquired GSF Explorer, an asset formerly held under a capital lease, in exchange for a cash payment of $15 million, thereby terminating the capital lease obligation. In connection with the termination of the capital lease obligation, we recognized a gain on debt retirement of $2 million. See Note 8—Drilling Fleet Expansion and Dispositions.

1.625% Series A, 1.50% Series B and 1.50% Series C Convertible Senior Notes—Holders may convert the Convertible Senior Notes under certain circumstances at a rate of 5.9310 shares per $1,000 note, subject to adjustment upon the occurrence of certain events and increase upon the occurrence of certain fundamental changes.

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

	March 31, 2010							December 31, 2009
	Principal amount		Unamortized discount			Carrying amount		Principal amount		Unamortized discount			Carrying amount
Carrying amount of liability component
Series A Convertible Senior Notes due 2037	$	1,299	$	(28	)	$	1,271	$	1,299	$	(38	)	$	1,261
Series B Convertible Senior Notes due 2037		2,200		(125	)		2,075		2,200		(143	)		2,057
Series C Convertible Senior Notes due 2037		2,200		(203	)		1,997		2,200		(221	)		1,979

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

	March 31, 2010		December 31, 2009
Carrying amount of equity component
Series A Convertible Senior Notes due 2037	$	215	$	215
Series B Convertible Senior Notes due 2037		275		275
Series C Convertible Senior Notes due 2037		352		352

Including the amortization of the unamortized discount, the effective interest rates were 4.88 percent for the Series A Notes, 5.08 percent for the Series B Notes, and 5.28 percent for the Series C Notes. At March 31, 2010, the remaining period over which the discount will be amortized was less than a year for the Series A Notes, 1.7 years for the Series B Notes and 2.7 years for the Series C Notes. Interest expense, excluding amortization of debt issue costs, was as follows (in millions):

	Three months ended March 31,
	2010		2009
Interest expense
Series A Convertible Senior Notes due 2037	$	15	$	25
Series B Convertible Senior Notes due 2037		26		25
Series C Convertible Senior Notes due 2037		26		25

During the three months ended March 31, 2010, we did not repurchase any of the Convertible Senior Notes. During the three months ended March 31, 2009, we repurchased an aggregate principal amount of $111 million of the 1.625% Series A Notes for an aggregate cash payment of $102 million. We recognized a loss on retirement of $2 million associated with the debt component of the 1.625% Series A Notes and recorded additional paid-in capital of $6 million associated with the equity component of the 1.625% Series A Notes.

Derivatives and Hedging	3 Months Ended
Derivatives and Hedging	Mar. 31, 2010
Notes To Financial Statements [Abstract]
Derivatives and Hedging	Note 10—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 notional value increased proportionately with the projected borrowings under the TPDI Credit Facilities to a maximum amount of $1.190 billion, of which $595 million is attributable to one of our subsidiaries. As of March 31, 2010, the aggregate notional value had increased to the maximum amount and the intercompany balances attributable to our subsidiary have been eliminated in consolidation. Under the interest rate swaps, TPDI receives interest at three-month London Interbank Offered Rate and pays interest at a weighted-average fixed rate of 2.3 percent during the expected term of the TPDI Credit Facilities. At March 31, 2010, the interest rate swaps represented a liability measured at fair value of $2 million, recorded in other long-term liabilities, with a corresponding increase to accumulated other comprehensive loss. The weighted-average variable interest rate on March 31, 2010 was 3.9 percent. At December 31, 2009, the interest rate swaps represented an asset measured at a fair value of $5 million, recorded in other assets, and a liability measured at fair value of less than $1 million, recorded in other long-term liabilities, with a corresponding decrease to accumulated other comprehensive loss on our consolidated balance sheet. 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. There was no ineffectiveness for the three months ended March 31, 2009. 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 values 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, 2010, the interest rate swaps represented an asset measured at fair value of $5 million, recorded in other assets, with a corresponding increase to the carrying amount of the underlying debt instrument. The weighted-average variable interest rate on March 31, 2010 was 3.4 percent. At December 31, 2009, the interest rate swaps represented a liability measured at a fair value of $4 million, recorded in other long-term liabilities, with a corresponding decrease to the carrying amount of the underlying debt instrument.

Postemployment Benefit Plans

3 Months Ended

Mar. 31, 2010

Notes To Financial Statements [Abstract]

Postemployment Benefit Plans

Note 11—Postemployment Benefit Plans

Defined benefit pension plans and other postretirement benefit plans

Overview—We have several defined benefit pension plans, both funded and unfunded, covering substantially all of our U.S. employees. We also have various defined benefit plans in the U.K., Norway, Nigeria, Egypt and Indonesia that cover our employees in those areas, and we have certain frozen plans assumed in connection with our mergers that cover certain of our current employees and former employees and directors of our predecessors.

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

	Three months ended March 31, 2010												Three months ended March 31, 2009
	U.S. Plans			Non-U.S. Plans			OPEB Plans			Total			U.S. Plans			Non-U.S. Plans			OPEB Plans		Total
Service cost	$	10		$	6		$	—		$	16		$	11		$	4		$	—	$	15
Interest cost		14			5			1			20			12			4			1		17
Expected return on plan assets		(14	)		(5	)		—			(19	)		(13	)		(3	)		—		(16	)
Settlements and curtailments		—			1			—			1			2			—			—		2
Actuarial losses, net		3			1			—			4			4			—			—		4
Prior service cost, net		—			—			(1	)		(1	)		—			—			—		—
Net periodic benefit costs	$	13		$	8		$	—		$	21		$	16		$	5		$	1	$	22

Funding contributions—During the three months ended March 31, 2010, we contributed an aggregate amount of $8 million to the U.S. Plans, the non-U.S. Plans and the other postretirement employee benefits plans, which was funded from our cash flows from operations.

Severance plan

Following our merger with GlobalSantaFe in 2007, we established a plan to consolidate operations and administrative functions. As of March 31, 2010, we had identified 377 employees who had been involuntarily terminated pursuant to this plan. We recognized $5 million and $6 million of severance expense in the three months ended March 31, 2010 and March 31, 2009, respectively, in either operating and maintenance expense or general and administrative expense. The liability associated with the severance plan, recorded in other current liabilities, was $14 million and $17 million at March 31, 2010 and December 31, 2009, respectively. Since the severance plan’s inception in 2007, we have paid $61 million in termination benefits under the plan, including $8 million and $4 million paid during the three months ended March 31, 2010 and March 31, 2009, respectively. No additional amounts will be recognized under the severance plan, which expired during the three months ended March 31, 2010.

- 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, 2010

Notes To Financial Statements [Abstract]

Contingencies

Note 12—Contingencies

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 17 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. None of the cases in which one of our subsidiaries is a named defendant has been scheduled for trial in 2010, and 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, and 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 been reviewed on appeal. The second case resulted in a verdict completely in favor of the defendants. There have been no other trials involving any of the parties to the original 21 complaints. 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, fundings from settlements with the primary insurers and funds received from the cancellation of certain insurance policies. The subsidiary has been named as a defendant, along with numerous other companies, in lawsuits alleging personal injury as a result of exposure to asbestos. As of March 31, 2010, the subsidiary was a defendant in approximately 1,054 lawsuits. Some of these lawsuits include multiple plaintiffs and we estimate that there are approximately 2,612 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, 2010, the amounts expended to resolve claims (including both attorneys’ fees and expenses, and settlement costs) have not been material, and all deductibles with respect to the primary insurance have been satisfied. 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 insurance and funds from the settlements of litigation with insurance carriers available 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 $164 million from the state tax authorities of Rio de Janeiro in Brazil against one of our Brazilian subsidiaries for taxes on equipment imported into the state in connection with our operations. The assessments resulted from a preliminary finding by these authorities that our subsidiary’s record keeping practices were deficient. We currently believe that the substantial majority of these assessments are without merit. We filed an initial response with the Rio de Janeiro tax authorities on September 9, 2006 refuting these additional tax assessments. In September 2007, we received confirmation from the state tax authorities that they believe the additional tax assessments are valid, and as a result, we filed an appeal on September 27, 2007 to the state Taxpayer’s Council contesting these assessments. While we cannot predict or provide assurance as to the final outcome of these proceedings, we do not expect it to have a material adverse effect on our consolidated statement of financial position, results of operations or cash flows.

Patent Litigation—Several of our subsidiaries have been sued by Heerema Engineering Services (“Heerema”) in the U.S. 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. They seek unspecified damages and injunctive relief. The court has held a hearing on construction of their patent but has not yet issued a decision. We deny liability for patent infringement, believe that their 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. In addition, as of March 31, 2010, 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. See Note 15—Subsequent Events.

Environmental matters

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 U.S. Department of Justice (“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 and/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 numbers 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 nineteen 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 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 codefendant filed a Notice of Appeal of the rulings of the Bankruptcy Court. GlobalSantaFe and its two subsidiaries also filed Notices of Appeal to the U.S. District Court for the District of Delaware. On January 27, 2009, the codefendant’s appeal was granted by the District Court and the bankruptcy case was remanded to the Bankruptcy Court with instructions to have the case dismissed. On February 10, 2009, the Bankruptcy Court entered an order dismissing the bankruptcy case. The debtors, GlobalSantaFe and the two subsidiaries have filed Notices of Appeal of the District Court’s ruling with the U.S. Court of Appeals for the Third Circuit. On February 18, 2009, the District Court stayed its ruling which instructed the Bankruptcy Court to dismiss the case. The appeal was heard on September 14, 2009. On December 22, 2009, the Court of Appeals affirmed the ruling of the District Court. On January 5, 2010, we petitioned the Third Circuit for a rehearing of that ruling. On January 27, 2010, the Third Circuit declined the petitions for rehearing and on February 4, 2010, the Third Circuit issued its mandate and the District Court responded by closing the appeal pending in the District Court the same day. The matter was then referred to the Bankruptcy Court for dismissal.

On February 1, 2010, the codefendant filed a motion for sanctions against the debtors, GlobalSantaFe and the two subsidiaries and counsel for all the companies based on the dismissal of the bankruptcy cases. Thereafter on February 12, 2010, the codefendant filed a motion to vacate the automatic stay. On March 10, 2010, a hearing was conducted in the Bankruptcy Court on the above motions. The motion for sanctions was taken under advisement by the Bankruptcy Court and, on the same day, the Bankruptcy Court entered an order vacating the automatic stay in the Bankruptcy Case in its entirety. The Bankruptcy Case remains open subject to the mandate and the pending motion for sanctions.

After entry of the order vacating the automatic stay, 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. 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.

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

Retained risk

Our insurance program consisted of commercial market and captive insurance policies primarily with 12 month policy periods beginning on May 1, 2009. Under the program, we generally maintain a $125 million per occurrence deductible, limited to a maximum of $250 million per year, on our hull and machinery. However, in the event of a total loss or a constructive total loss of a drilling unit, such loss would be subject to a deductible ranging from $0.5 million to $1.5 million. 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 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. 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 separate (1) $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 and/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. Generally, ADTI’s customers assume, and indemnify ADTI for, liability associated with blowouts in excess of $50 million.

As of March 31, 2010, the insured value of our drilling rig fleet was approximately $39 billion in the aggregate. See Note 15—Subsequent Events.

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 $500 million and $567 million at March 31, 2010 and December 31, 2009, respectively. These letters of credit guarantee various contract bidding and performance activities under various committed and uncommitted credit lines provided by several banks.

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 $31 million at March 31, 2010 and December 31, 2009.

Equity	3 Months Ended
Equity	Mar. 31, 2010
Notes To Financial Statements [Abstract]
Equity	Note 13—Equity Share repurchase program—In May 2009, at our annual general meeting, our shareholders approved and authorized our board of directors, at its discretion, to repurchase an amount of our shares for cancellation with an aggregate purchase price of up to CHF 3.5 billion, which is equivalent to approximately U.S. $3.3 billion, using an exchange rate of U.S. $1.00 to CHF 1.05 as of the close of trading on March 31, 2010. On February 12, 2010, our board of directors authorized our management to implement the share repurchase program. During the three months ended March 31, 2010, following the authorization by our board of directors, we repurchased 717,000 of our shares under our share repurchase program in exchange for CHF 64 million, equivalent to $60 million. At March 31, 2010, we held 717,000 treasury shares purchased under our share repurchase program, recorded at cost. See Note 15—Subsequent Events. 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 March 31, 2010 and December 31, 2009, our subsidiary had 13,567,674 shares and 14,011,416 shares, respectively, available for this purpose.

- 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.

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Fair Value of Financial Instruments

3 Months Ended

Mar. 31, 2010

Notes To Financial Statements [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 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.

Short-term investments—The carrying amount represents the estimated fair value, measured using pricing data that are representative of quoted prices for similar instruments in active markets or identical instruments in less active markets. Our short-term investments include investments in The Reserve International Liquidity Fund Ltd. and The Reserve Primary Fund. At March 31, 2010 and December 31, 2009, the carrying amount of our short-term investments was $32 million and $38 million, respectively, recorded in other assets on our condensed consolidated balance sheets.

Notes 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. At March 31, 2010, the aggregate carrying amount of our notes receivable was $130 million, including $19 million and $111 million recorded in other current assets and other assets, respectively. We did not hold notes receivable as of December 31, 2009.

Debt—The fair value of our fixed-rate debt is measured using quoted prices for identical instruments in 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 Loan Facility are included in the fair values stated below at their aggregate carrying amount of $158 million at March 31, 2010 and December 31, 2009, 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, 2010				December 31, 2009
	Carrying amount		Fair value		Carrying amount		Fair value

Long-term debt, including current maturities	$	10,437	$	11,047	$	10,534	$	11,218
Long-term debt of consolidated variable interest entities, including current maturities		1,002		1,004		1,183		1,178

Derivative instruments—The carrying amount of our derivative instruments represents the estimated fair value, measured using pricing data, including quoted prices and other observable market data, for the instruments. The carrying amount of our derivative instruments were $5 million and $2 million at March 31, 2010 and $5 million and $5 million at December 31, 2009, recorded in other assets and other long-term liabilities, respectively, on our condensed 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.

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Entity Information (USD $)	3 Months Ended
Entity Information (USD $)	Mar. 31, 2010	Apr. 27, 2010	Jun. 30, 2009
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			$ 23,800,000,000
Entity Common Stock, Shares Outstanding		319,933,046
Document Fiscal Year Focus	2010
Document Fiscal Period Focus	Q1

Nature of Business	3 Months Ended
Nature of Business	Mar. 31, 2010
Notes To Financial Statements [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, 2010, we owned, had partial ownership interests in or operated 140 mobile offshore drilling units. As of this date, our fleet consisted of 46 High-Specification Floaters (Ultra-Deepwater, Deepwater and Harsh Environment semisubmersibles and drillships), 26 Midwater Floaters, 10 High-Specification Jackups, 55 Standard Jackups and three Other Rigs (see Note 15—Subsequent Events). We also have three Ultra-Deepwater Floaters under construction (see Note 8—Drilling Fleet Expansion and Dispositions). We also provide oil and gas drilling management services, drilling engineering and drilling project management services, and we participate in oil and gas exploration and production activities. Drilling management services are provided 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. Oil and gas properties consist of exploration, development and production activities performed by Challenger Minerals Inc. and Challenger Minerals (North Sea) Limited (together, “CMI”), our oil and gas subsidiaries.

Impairments	3 Months Ended
Impairments	Mar. 31, 2010
Notes To Financial Statements [Abstract]
Impairments	Note 5—Impairments During the three months ended March 31, 2010, we recognized a $2 million loss on impairment of goodwill associated with our oil and gas properties. During the three months ended March 31, 2009, we determined that GSF Arctic II and GSF Arctic IV, both previously classified as assets held for sale, were impaired due to the global economic downturn and pressure on commodity prices, both of which have had an adverse effect on our industry. We estimated the fair values of these rigs as of the measurement date based on an exchange price that would be received for the assets in the principal or most advantageous market for the assets in an orderly transaction between market participants and considering our undertakings to the Office of Fair Trading in the U.K. (“OFT”) that required the sale of the rigs with certain limitations and in a limited amount of time. We based our estimates on unobservable inputs that require significant judgment, for which there is little or no market data, including non-binding price quotes from unaffiliated parties with consideration of the then-current market conditions and restrictions imposed by the OFT. As a result of our evaluation, we recognized a loss on impairment of $221 million ($0.69 per diluted share), which had no tax effect, for the three months ended March 31, 2009. See Note 8—Drilling Fleet Expansion and Dispositions.

Document Information	3 Months Ended
Document Information	Mar. 31, 2010
Document Type	10-Q
Document Period End Date	Mar. 31, 2010
Amendment Flag	false

Subsequent Events	3 Months Ended
Subsequent Events	Mar. 31, 2010
Notes To Financial Statements [Abstract]
Subsequent Events	Note 15—Subsequent Events Share repurchase program—Subsequent to March 31, 2010, we repurchased 1,732,900 of our shares under our share repurchase program in exchange for an aggregate amount of CHF 160 million, equivalent to $150 million. At May 5, 2010, we held 2,449,900 treasury shares, at cost. Deepwater Horizon incident—Subsequent to March 31, 2010, our Ultra-Deepwater Floater Deepwater Horizon, which had been drilling a well for its operator in the U.S. Gulf of Mexico, sank on April 22, 2010 after an explosion and fire onboard the rig that began on April 20, 2010. Eleven persons are missing and presumed dead and others were injured as a result of the incident. Our underwriters declared the vessel a total loss and, as of May 5, 2010, we received $401 million as partial payment of the expected insurance recoveries. The combined response team was unable to stem the flow of hydrocarbons from the well prior to the sinking of the rig and efforts to contain the flow of hydrocarbons are still underway. The Departments of Homeland Security and Interior have begun a joint investigation into the cause of the incident. The U.S. Coast Guard and the Minerals Management Service share jurisdiction over the investigation into the incident. In addition, various committees and subcommittees of the House of Representatives and the Senate of the United States have requested our participation in hearings related to the incident. We have also received a request to preserve information from the DOJ. There have also been numerous lawsuits filed related to the incident, and we expect additional lawsuits to be filed. We expect to incur significant legal fees and costs in responding to these matters.