Transocean (RIG) 10-Q 30 Oct 18 2018 Q3 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	9 Months Ended
	Sep. 30, 2018	Oct. 22, 2018
Document and Entity Information
Entity Registrant Name	Transocean Ltd.
Entity Central Index Key	1,451,505
Document Type	10-Q
Document Period End Date	Sep. 30, 2018
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		461,906,035
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q3
Entity Small Business	false
Entity Emerging Growth Company	false

CONSOLIDATED STATEMENTS OF OPER

CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Operating revenues
Revenues	$ 816	$ 808	$ 2,270	$ 2,344
Costs and expenses
Operating and maintenance	447	325	1,302	1,003
Depreciation	201	197	614	648
General and administrative	35	39	134	113
Total costs and expenses	683	561	2,050	1,764
Loss on impairment	(432)	(1,385)	(1,446)	(1,498)
Loss on disposal of assets, net	(6)	(9)		(1,602)
Operating loss	(305)	(1,147)	(1,226)	(2,520)
Other income (expense), net
Interest income	11	21	36	34
Interest expense, net of amounts capitalized	(160)	(112)	(455)	(368)
Loss on retirement of debt	(1)	(1)	(3)	(49)
Other, net	16	8	6	11
Total other income (expense), net	(134)	(84)	(416)	(372)
Loss before income tax expense (benefit)	(439)	(1,231)	(1,642)	(2,892)
Income tax expense (benefit)	(30)	180	118	103
Net loss	(409)	(1,411)	(1,760)	(2,995)
Net income (loss) attributable to noncontrolling interest		6	(6)	21
Net loss attributable to controlling interest	$ (409)	$ (1,417)	$ (1,754)	$ (3,016)
Loss per share
Basic (in dollars per share)	$ (0.88)	$ (3.62)	$ (3.86)	$ (7.72)
Diluted (in dollars per share)	$ (0.88)	$ (3.62)	$ (3.86)	$ (7.72)
Weighted-average shares outstanding
Basic (in shares)	463	391	454	391
Diluted (in shares)	463	391	454	391
Contract drilling revenues
Operating revenues
Revenues	$ 816	$ 699	$ 2,270	$ 2,142
Other revenues
Operating revenues
Revenues		$ 109		$ 202

CONSOLIDATED STATEMENTS OF COMP

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)
Net loss	$ (409)	$ (1,411)	$ (1,760)	$ (2,995)
Net income (loss) attributable to noncontrolling interest		6	(6)	21
Net loss attributable to controlling interest	(409)	(1,417)	(1,754)	(3,016)
Components of net periodic benefit costs before reclassifications	(1)		(4)	(2)
Components of net periodic benefit costs reclassified to net income	2	4	4	12
Other comprehensive income (loss) before income taxes	1	4		10
Income taxes related to other comprehensive income (loss)		(2)		(25)
Other comprehensive income (loss)	1	2		(15)
Other comprehensive income (loss) attributable to controlling interest	1	2		(15)
Total comprehensive loss	(408)	(1,409)	(1,760)	(3,010)
Total comprehensive income (loss) attributable to noncontrolling interest		6	(6)	21
Total comprehensive loss attributable to controlling interest	$ (408)	$ (1,415)	$ (1,754)	$ (3,031)

CONSOLIDATED BALANCE SHEETS

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Assets
Cash and cash equivalents	$ 2,307	$ 2,519
Short-term investments		450
Accounts receivable, net of allowance for doubtful accounts of less than $1 at September 30, 2018 and December 31, 2017	627	596
Materials and supplies, net of allowance for obsolescence of $139 and $141 at September 30, 2018 and December 31, 2017, respectively	401	418
Restricted cash accounts and investments	561	466
Other current assets	169	157
Total current assets	4,065	4,606
Property and equipment	23,565	22,693
Less accumulated depreciation	(5,206)	(5,291)
Property and equipment, net	18,359	17,402
Contract intangible assets	554
Deferred income taxes, net	40	47
Other assets	444	355
Total assets	23,462	22,410
Liabilities and equity
Accounts payable	172	201
Accrued income taxes	26	79
Debt due within one year	372	250
Other current liabilities	752	839
Total current liabilities	1,322	1,369
Long-term debt	8,955	7,146
Deferred income taxes, net	75	44
Other long-term liabilities	1,149	1,082
Total long-term liabilities	10,179	8,272
Commitments and contingencies
Redeemable noncontrolling interest		58
Shares, CHF 0.10 par value, 490,584,698 authorized, 143,754,927 conditionally authorized, 462,880,809 issued and 461,903,386 outstanding at September 30, 2018, and 417,060,033 authorized, 143,783,041 conditionally authorized, 394,801,990 issued and 391,237,308 outstanding at December 31, 2017	44	37
Additional paid-in capital	12,033	11,031
Retained earnings	175	1,929
Accumulated other comprehensive loss	(290)	(290)
Total controlling interest shareholders' equity	11,962	12,707
Noncontrolling interest	(1)	4
Total equity	11,961	12,711
Total liabilities and equity	$ 23,462	$ 22,410

CONSOLIDATED BALANCE SHEETS (Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical) $ in Millions	Sep. 30, 2018SFr / shares	Sep. 30, 2018USD ($)shares	Dec. 31, 2017SFr / shares	Dec. 31, 2017USD ($)shares
Materials and supplies, allowance for obsolescence | $		$ 139		$ 141
Shares, CHF par value (in Swiss francs per share) | SFr / shares	SFr 0.10		SFr 0.10
Shares, authorized		490,584,698		417,060,033
Shares, conditionally authorized		143,754,927		143,783,041
Shares, issued		462,880,809		394,801,990
Shares, outstanding		461,903,386		391,237,308
Maximum
Allowance for doubtful accounts | $		$ 1		$ 1

CONDENSED CONSOLIDATED STATEMEN

CONDENSED CONSOLIDATED STATEMENTS OF EQUITY - USD ($) shares in Millions, $ in Millions	Total controlling interest shareholders' equity	Shares	Additional paid-in capital	Retained earnings	Accumulated other comprehensive loss	Noncontrolling interest	Total
Balance at Dec. 31, 2016	$ 15,802	$ 36	$ 10,993	$ 5,056	$ (283)	$ 3	$ 15,805
Balance (in shares) at Dec. 31, 2016		389
Increase (Decrease) in Shareholders' Equity
Issuance of shares under share-based compensation plans		$ 1	(1)
Issuance of shares under share-based compensation plans (in shares)		2
Share-based compensation	30		30				30
Net loss attributable to controlling interest				(3,016)			(3,016)
Other comprehensive loss attributable to controlling interest					(15)		(15)
Total comprehensive income (loss) attributable to noncontrolling interest						1
Total comprehensive loss attributable to controlling interest	(3,031)						(3,031)
Total comprehensive loss							(3,030)
Other, net	(2)		(2)				(2)
Balance at Sep. 30, 2017	12,799	$ 37	11,020	2,040	(298)	4	12,803
Balance (in shares) at Sep. 30, 2017		391
Balance at Dec. 31, 2017	12,707	$ 37	11,031	1,929	(290)	4	12,711
Balance (in shares) at Dec. 31, 2017		391
Increase (Decrease) in Shareholders' Equity
Issuance of shares under share-based compensation plans (in shares)		3
Issuance of shares in acquisition transactions	746	$ 7	739				746
Issuance of shares in acquisition transactions (in shares)		68
Share-based compensation	36		36				36
Equity component of convertible debt instruments	172		172				172
Acquisition of redeemable noncontrolling interest	53		53				53
Net loss attributable to controlling interest				(1,754)			(1,754)
Total comprehensive income (loss) attributable to noncontrolling interest						(2)
Total comprehensive loss attributable to controlling interest	(1,754)						(1,754)
Total comprehensive loss							(1,756)
Recognition of noncontrolling interest in business combination						33	33
Acquisition of noncontrolling interest						(31)	(31)
Allocated capital for transactions with holders of noncontrolling interest	5		5			(5)
Other, net	(3)		(3)				(3)
Balance at Sep. 30, 2018	$ 11,962	$ 44	$ 12,033	$ 175	$ (290)	$ (1)	$ 11,961
Balance (in shares) at Sep. 30, 2018		462

CONDENSED CONSOLIDATED STATEM_2

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017
Cash flows from operating activities
Net loss	$ (409)	$ (1,760)	$ (2,995)
Adjustments to reconcile to net cash provided by operating activities:
Contract intangible asset amortization	29	78
Depreciation	201	614	648
Share-based compensation expense		36	30
Loss on impairment	432	1,446	1,498
Loss on disposal of assets, net			1,602
Loss on retirement of debt	1	3	49
Deferred income tax expense (benefit)		50	32
Other, net		12	29
Changes in deferred revenues, net		(127)	(109)
Changes in deferred costs, net		23	42
Changes in other operating assets and liabilities, net		(55)	100
Net cash provided by operating activities		320	926
Cash flows from investing activities
Capital expenditures		(140)	(386)
Proceeds from disposal of assets, net		37	330
Unrestricted and restricted cash acquired in business combination		131
Investment in unconsolidated affiliates		(107)
Deposits into short-term investments		(50)
Proceeds from maturities of short-term investments		500
Other, net			10
Net cash provided by (used in) investing activities		371	(46)
Cash flows from financing activities
Proceeds from issuance of debt, net of discounts and issue costs		1,319	403
Repayments of debt		(2,015)	(1,629)
Proceeds from investments restricted for financing activities		26	102
Payments to terminate derivative instruments		(92)
Other, net		(29)	(3)
Net cash used in financing activities		(791)	(1,127)
Net decrease in unrestricted and restricted cash and cash equivalents		(100)	(247)
Unrestricted and restricted cash and cash equivalents at beginning of period		2,975	3,433
Unrestricted and restricted cash and cash equivalents at end of period	$ 2,875	$ 2,875	$ 3,186

Business

Business	9 Months Ended
	Sep. 30, 2018
Business
Business	Note 1—Business Overview —Transocean Ltd. (together with its subsidiaries and predecessors, unless the context requires otherwise, “Transocean,” “we,” “us” or “our”) is a leading international provider of offshore contract drilling services for oil and gas wells. We specialize in technically demanding sectors of the offshore drilling business with a particular focus on ultra‑deepwater and harsh environment drilling services. Our mobile offshore drilling fleet is considered one of the most versatile fleets in the world. We contract our drilling rigs, related equipment and work crews predominantly on a dayrate basis to drill oil and gas wells. As of September 30, 2018, we owned or had partial ownership interests in and operated 41 mobile offshore drilling units, including 23 ultra‑deepwater floaters, 12 harsh environment floaters, two deepwater floaters and four midwater floaters. As of September 30, 2018, we were constructing (i) two additional ultra‑deepwater drillships and (ii) one harsh environment semisubmersible, in which we hold a partial ownership interest. We also operated one high‑specification jackup that was under a drilling contract when the rig was sold, and we continue to operate the rig until completion or novation of the drilling contract. See Note 6—Drilling Fleet. Merger agreement —On September 4, 2018, we announced that we entered into a definitive merger agreement (the “Merger Agreement”) with Ocean Rig UDW Inc., a Cayman Islands exempted company with limited liability (“Ocean Rig”), under which we agreed to acquire Ocean Rig in a cash and stock transaction. The transaction consideration is comprised of 1.6128 newly issued shares of Transocean Ltd. plus $12.75 in cash for each common share of Ocean Rig. As of September 30, 2018, Ocean Rig owned and operated 11 mobile offshore drilling units, including nine ultra‑deepwater floaters and two harsh environment floaters. As of September 30, 2018, Ocean Rig was also constructing two ultra‑deepwater drillships. See Note 4—Business Combinations, Note 13—Equity and Note 15—Subsequent Event. Business combination —On January 30, 2018, we acquired an approximate 97.7 percent ownership interest in Songa Offshore SE, a European public company limited by shares, or societas Europaea, existing under the laws of Cyprus (“Songa”). On March 28, 2018, we acquired the remaining shares not owned by us through a compulsory acquisition under Cyprus law, and as a result, Songa became our wholly owned subsidiary. In connection with these transactions, we issued an aggregate of 68.0 million shares and $863 million aggregate principal amount of 0.50% exchangeable senior bonds due January 30, 2023 (the “Exchangeable Bonds”). As a result of the acquisition, we acquired seven mobile offshore drilling units, including five harsh environment floaters and two midwater floaters. See Note 4—Business Combinations. Investment in unconsolidated affiliates —In the nine months ended September 30, 2018, we made an aggregate cash investment of $107 million in unconsolidated affiliates, including an initial investment of $91 million, representing a 33.0 percent interest, in Orion Holdings (Cayman) Limited, a Cayman Islands company formed to construct and own the newbuild harsh environment semisubmersible Transocean Norge . We account for this investment, recorded in other assets, using the equity method of accounting . The total purchase price for the rig, under construction at the Jurong Shipyard Pte Ltd. in Singapore, is $500 million. We expect to make additional investments of $50 million and $33 million in January 2019 and January 2020, respectively. We expect to operate the rig, through one of our wholly owned subsidiaries, under a drilling contract that is expected to commence in July 2019. Additionally, we invested $16 million in other companies, recorded in other assets using the cost method of accounting, that are involved in researching and developing technology to improve automation in drilling and other activities.

Significant Accounting Policies

Significant Accounting Policies	9 Months Ended
	Sep. 30, 2018
Significant Accounting Policies
Significant Accounting Policies	Note 2—Significant Accounting Policies 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. 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 and nine months ended September 30, 2018, are not necessarily indicative of the results that may be expected for the year ending December 31, 2018, 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, 2017 and 2016, and for each of the three years in the period ended December 31, 2017, included in our annual report on Form 10‑K filed on February 21, 2018. 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, assets held for sale, goodwill, income taxes, contingencies, share‑based compensation and postemployment benefit plans. We base our estimates and assumptions on historical experience and on various other factors we believe are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying amounts of assets and liabilities that are not readily apparent from other sources. Actual results could differ from such estimates. Fair value measurements —We estimate fair value at a price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants in the principal market for the asset or liability. Our valuation techniques require inputs that we categorize using a three‑level hierarchy, from highest to lowest level of observable inputs, as follows: (1) significant observable inputs, including unadjusted quoted prices for identical assets or liabilities in active markets (“Level 1”), (2) significant other observable inputs, including direct or indirect market data for similar assets or liabilities in active markets or identical assets or liabilities in less active markets (“Level 2”) and (3) significant unobservable inputs, including those that require considerable judgment for which there is little or no market data (“Level 3”). When multiple input levels are required for a valuation, we categorize the entire fair value measurement according to the lowest level of input that is significant to the measurement even though we may have also utilized significant inputs that are more readily observable. Business combination —In connection with the Songa acquisition, we applied the acquisition method of accounting. Accordingly, we recorded the acquired assets and assumed liabilities at fair value and recognized goodwill to the extent the consideration transferred exceeded the fair value of the net assets acquired. We estimated the fair values of the acquired assets and assumed liabilities as of the date of the acquisition, and our estimates are subject to adjustment based on our final assessments of the fair values of property and equipment, intangible assets, other assets and liabilities and our evaluation of tax positions and contingencies, which are ongoing. We will complete our final assessments of the fair values of the acquired assets and assumed liabilities and our final evaluations of uncertain tax positions and contingencies within one year of the acquisition date. See Note 4—Business Combinations. Goodwill —We conduct impairment testing for our goodwill annually as of October 1 and more frequently, on an interim basis, when an event occurs or circumstances change that indicate that the fair value of our reporting unit may have declined below its carrying value. We test goodwill at the reporting unit level, which is defined as an operating segment or one level below an operating segment that constitutes a business for which financial information is available and is regularly reviewed by management. We determined that we have a single reporting unit for this purpose. Before testing goodwill, we consider whether or not to first assess qualitative factors to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If, as the result of our qualitative assessment, we determine that an impairment test is required, or, alternatively, if we elect to forgo the qualitative assessment, we record an impairment to goodwill to the extent the carrying amount of the reporting unit, including goodwill, exceeds the fair value of the reporting unit. In the nine months ended September 30, 2018, as a result of an interim goodwill test, we recognized an aggregate loss of $462 million, which had no tax effect, associated with the impairment of our goodwill. See Note 3—Accounting Standards Updates, Note 4—Business Combinations and Note 7—Goodwill. Contract intangible assets —In connection with the Songa acquisition, we recognized drilling contract intangible assets related to the acquired drilling contracts for future contract drilling services. The drilling contract intangible assets represent the amount by which the fixed dayrates of the acquired contracts were above the market dayrates that were available or expected to be available during the term of the contract for similar contracts, measured as of the acquisition date. We recognize the amortization on a straight‑line basis over the firm contract period as a reduction of contract drilling revenues. At September 30, 2018, the carrying amount of our drilling contract intangible assets was $554 million. See Note 4—Business Combinations. Derivative instruments —We record derivatives on our consolidated balance sheet, measured at fair value. We recognize the gains and losses associated with changes in the fair value of undesignated derivatives in current period earnings. See Note 9—Derivative Instruments. Capitalized interest —We capitalize interest costs for qualifying construction and upgrade projects and only capitalize interest costs during periods in which progress for the construction projects continues to be underway. In the three and nine months ended September 30, 2018, we capitalized interest costs of $8 million and $28 million, respectively, for our construction work in progress. In the three and nine months ended September 30, 2017, we capitalized interest costs of $31 million and $91 million, respectively, for our construction work in progress. Reclassifications —We have made certain reclassifications to prior period amounts to conform with the current period’s presentation. In our condensed consolidated balance sheet as of December 31, 2017, we reclassified certain balances receivable from non‑customers, totaling $45 million, from accounts receivable, net, to other current assets. Such reclassifications did not have a material effect on our condensed consolidated statement of financial position, results of operations or cash flows.

Accounting Standards Updates

Accounting Standards Updates	9 Months Ended
	Sep. 30, 2018
Accounting Standards Updates
Accounting Standards Updates	Note 3—Accounting Standards Updates Recently adopted accounting standards Revenue from contracts with customers —Effective January 1, 2018, we adopted the accounting standards update that requires an entity to recognize revenue in a manner that depicts the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In our evaluation of the requirements, we determined that reimbursement revenues and contract early cancellation and termination fees were part of our single performance obligation, and we determined that reimbursement revenues should be recorded on a gross basis as the service is performed. Our adoption, using the modified retrospective approach, for which we were not required to make any changes to the prior year presentation, did not have a material effect on our condensed consolidated statements of financial position, operations and cash flows. See Note 5—Revenues. Income taxes —Effective January 1, 2018, we adopted the accounting standards update that requires an entity to recognize the income tax consequences of an intra entity transfer of an asset other than inventory when the transaction occurs as opposed to deferring such recognition into future periods. Our adoption did not have a material effect on our condensed consolidated statements of financial position, operations or cash flows or on the disclosures contained in our notes to condensed consolidated financial statements. Statement of cash flows —Effective January 1, 2018, we adopted the accounting standards update that requires amounts generally described as restricted cash or restricted cash equivalents to be included with cash and cash equivalents when reconciling the beginning and end of period total amounts presented on the statement of cash flows. Aside from presenting the restricted cash and restricted cash equivalents as a component of the beginning and ending cash balances on our condensed consolidated statements of cash flows, we removed the effect of proceeds from and deposits to restricted accounts from our cash flows provided by or used in operating and financing activities, as applicable. For the nine months ended September 30, 2018 and 2017, such changes did not have a material effect on our condensed consolidated statements of financial position, operations or cash flows or on the disclosures contained in our notes to condensed consolidated financial statements. Retirement benefits —Effective January 1, 2018, we adopted the accounting standards update that requires an employer to disaggregate the service cost component from the other components of net benefit cost related to defined benefit retirement plans and other postemployment benefit plans. The update requires that the service cost component be presented in the same line item as other compensation costs for employees and the other components of net benefit cost in other income and expense on our condensed consolidated statements of operations. The update also allows only the service cost component of net benefit cost to be eligible for capitalization. Our adoption did not have a material effect on our condensed consolidated statements of financial position, operations or cash flows or on the disclosures contained in our notes to condensed consolidated financial statements. Goodwill —Effective January 1, 2018, we early adopted the accounting standards update that simplifies the method for measuring the implied value of goodwill when performing a goodwill impairment test by performing a one‑step test, comparing the fair value of the reporting unit with its carrying amount. The update eliminates the two‑step requirement to perform procedures to determine the fair value of assets and liabilities on the same basis as required in a business combination. The update, which permits early adoption, is effective for interim and annual periods beginning after December 15, 2019, including interim periods within those annual periods. Our adoption did not have an effect on our condensed consolidated statements of financial position, operations or cash flows or on the disclosures contained in our notes to condensed consolidated financial statements. Recently issued accounting standards Leases —Effective January 1, 2019, we will adopt the accounting standards update that (a) requires lessees to recognize a right to use asset and a lease liability for virtually all leases, and (b) updates previous accounting standards for lessors to align certain requirements with the updates to lessee accounting standards and the revenue recognition accounting standards. Under the updated definition of a lease, we have determined that our drilling contracts could contain a lease component. In a recent update, targeted improvements were made to the accounting standards that provide for (a) an optional new transition method for adoption that results in initial recognition of a cumulative effect adjustment to retained earnings in the year of adoption and (b) a practical expedient for lessors, under certain circumstances, to combine the lease and non‑lease components of revenues for presentation purposes. We expect to elect the new optional transition method of adoption. Our adoption, and the ultimate effect on our consolidated financial statements, will be based on an evaluation of the contract‑specific facts and circumstances. Based on the lease arrangements under which we are the lessee as of September 30, 2018, we expect to recognize an aggregate lease liability and a corresponding right-to-use asset of between $65 million and $75 million. Additionally, as of September 30, 2018, we have entered into a lease arrangement that is expected to commence prior to December 31, 2018, for which we expect to recognize an incremental lease liability of between $60 million and $65 million. We do not expect our adoption to have a material effect on our condensed consolidated statements of financial position, operations or cash flows. We continue to evaluate the requirements with regard to arrangements under which we are the lessor, the targeted updates and the effects such requirements may have on the disclosures contained in our notes to condensed consolidated financial statements. Other comprehensive income —Effective January 1, 2019, we will adopt the accounting standards update that allows for reclassification from accumulated other comprehensive income to retained earnings for stranded tax effects resulting from the Tax Cuts and Jobs Act of 2017 (the “2017 Tax Act”). We continue to evaluate the requirements and do not expect our adoption to have a material effect on our condensed consolidated statements of financial position, operations or cash flows or on the disclosures contained in our notes to condensed consolidated financial statements. Financial instruments – credit losses —Effective no later than January 1, 2020, we will adopt the accounting standards update that requires entities to estimate an expected lifetime credit loss on financial assets ranging from short-term trade accounts receivable to long-term financings. The update, which permits early adoption, is effective for annual reporting periods beginning after December 15, 2019, including interim periods within those fiscal years. We continue to evaluate the requirements and do not expect our adoption to have a material effect on our condensed consolidated statements of financial position, operations or cash flows or on the disclosures contained in our notes to condensed consolidated financial statements.

Business Combinations

Business Combinations	9 Months Ended
	Sep. 30, 2018
Business Combinations
Business Combinations	Note 4—Business Combinations Ocean Rig UDW Inc. On September 4, 2018, we announced that we entered into the Merger Agreement with Ocean Rig, under which we agreed to acquire Ocean Rig in a cash and stock transaction. The transaction consideration is comprised of 1.6128 newly issued shares of Transocean Ltd. plus $12.75 in cash for each common share of Ocean Rig. Based on the number of Ocean Rig shares outstanding, we expect to issue approximately 147.7 million shares and make an aggregate cash payment of approximately $1.17 billion pursuant to the Merger Agreement. We expect to fund the consideration through a combination of proceeds from the issuance of debt and unrestricted cash balances. As of September 30, 2018, Ocean Rig owned and operated 11 mobile offshore drilling units, including nine ultra‑deepwater floaters and two harsh environment floaters. As of September 30, 2018, Ocean Rig was also constructing two ultra‑deepwater drillships. The Merger Agreement is subject to the satisfaction of customary closing conditions for a transaction of this type. We expect to complete the transaction before December 31, 2018. If completed, we will account for the transaction using the acquisition method of accounting, pursuant to which we will record the consideration transferred, the assets acquired and the liabilities assumed at fair value, measured as of the acquisition date. See Note 13—Equity and Note 15—Subsequent Event. Songa Offshore SE Overview —On January 30, 2018, we acquired an approximate 97.7 percent ownership interest in Songa. We believe the Songa acquisition strengthens our position as a leader in harsh environment and ultra‑deepwater drilling services by adding high value assets, including four high‑specification harsh environment floaters, supported by significant contract backlog. Additionally, the acquisition strengthens our footprint in harsh environment operating areas. The goodwill resulting from the business combination was attributed to synergies and intangible assets that did not qualify for separate recognition. In the nine months ended September 30, 2018 and 2017, we incurred acquisition costs of $7 million and $3 million, respectively, recorded in general and administrative costs and expenses. Consideration —In connection with the acquisition, we issued 66.9 million shares with a market value of $10.99 per share, based on the market value of our shares on the acquisition date. We also issued $854 million aggregate principal amount of Exchangeable Bonds, including $562 million aggregate principal amount as partial consideration to Songa shareholders and $292 million aggregate principal amount as settlement for certain Songa indebtedness. The aggregate fair value of the consideration transferred in the business combination was as follows (in millions): Total Consideration transferred Aggregate fair value of shares issued as partial consideration for Songa shares $ 735 Aggregate fair value of Exchangeable Bonds issued as partial consideration for Songa shares 675 Consideration transferred to Songa shareholders 1,410 Aggregate fair value of Exchangeable Bonds issued for settlement of certain Songa indebtedness 351 Total consideration transferred in business combination $ 1,761 Assets and liabilities —We estimated the fair value of assets acquired, liabilities assumed and noncontrolling interest, measured as of January 30, 2018, as follows (in millions): Total Assets acquired Cash and cash equivalents $ 113 Accounts receivable 115 Other current assets 80 Property and equipment 2,414 Goodwill 462 Contract intangible assets 632 Liabilities assumed Accounts payable and other current liabilities 178 Debt 1,768 Other long-term liabilities 76 Net assets acquired 1,794 Noncontrolling interest in business combination 33 Controlling interest acquired in business combination $ 1,761 We estimated the fair value of the rigs and related equipment by applying a combination of income and market approaches, using projected discounted cash flows and estimates of the exchange price that would be received for the assets in the principal or most advantageous markets for the assets in an orderly transaction between participants as of the acquisition date. Additionally, we estimated the fair value of the drilling contracts by comparing the contractual dayrates over the remaining firm contract term and option periods relative to the projected market dayrates as of the acquisition date. Our estimates of fair value for these assets required us to use significant unobservable inputs, representative of a Level 3 fair value measurement, including assumptions related to the future performance of our contract drilling services reporting unit, such as future commodity prices, projected demand for our services, rig availability and dayrates. We estimated the fair value of the debt using significant other observable inputs, representative of a Level 2 fair value measurement, including the terms and credit spreads for the instruments. We have not completed our estimates of the fair values of assets acquired and liabilities assumed. We continue to review the estimated fair values of property and equipment, intangible assets, and other assets and liabilities, and to evaluate the assumed tax positions and contingencies. Estimating fair value for such assets and liabilities requires significant assumptions and judgment, which increases the likelihood that the estimates may require adjustment, and such adjustments could be material. Noncontrolling interest —On March 28, 2018, we acquired the remaining Songa shares not owned by us through a compulsory acquisition under Cyprus law, and as a result, Songa became our wholly owned subsidiary. As consideration for the remaining Songa shares, we issued 1.1 million shares and $9 million aggregate principal amount of Exchangeable Bonds and we made an aggregate cash payment of $8 million to Songa shareholders who elected to receive a cash payment or failed to make an election, for an aggregate fair value of $30 million. Contract intangible assets —In the three and nine months ended September 30, 2018, we recognized contract intangible amortization of $29 million and $78 million, respectively, recorded as a reduction of contract drilling revenues. At September 30, 2018, the aggregate carrying amount of contract intangible assets was $554 million, which we expect to amortize over the remaining contract periods, through March 2024. As of September 30, 2018, the estimated future amortization of contract intangible assets was as follows (in millions): Total Twelve months ending September 30, 2019 $ 117 2020 117 2021 117 2022 117 2023 74 Thereafter 12 Total carrying amount of contract intangible assets $ 554 Pro forma combined operating results —We have included the operating results of Songa in our condensed consolidated results of operations, commencing on the acquisition date, January 30, 2018. In the three and nine months ended September 30, 2018, our condensed consolidated statement of operations includes revenues of $137 million and $356 million, respectively, and net income of $16 million and $36 million, respectively, associated with the operations of Songa. Pro forma combined operating results, assuming the acquisition was completed as of January 1, 2017, were as follows (in millions, except per share data): Three months ended Nine months ended September 30, September 30, 2018 2017 2018 2017 Contract drilling revenues $ 816 $ 954 $ 2,319 $ 2,749 Net loss (409) (1,417) (1,753) (2,977) Per share loss - basic and diluted (0.88) (3.11) (3.79) (6.55) The pro forma financial information includes various adjustments, primarily related to additional depreciation resulting from the fair value adjustments to the acquired property and equipment and amortization resulting from the contract intangible assets. The pro forma information is not necessarily indicative of the results of operations had the Songa acquisition been completed on the assumed dates or the results of operations for any future periods.

Revenues

Revenues	9 Months Ended
	Sep. 30, 2018
Revenues
Revenues	Note 5—Revenues Overview —The services we perform represent a single performance obligation under our drilling contracts with customers that is satisfied over time. We earn revenues primarily by performing the following activities: (i) providing our drilling rig, work crews, related equipment and services necessary to operate the rig (ii) delivering the drilling rig by mobilizing to and demobilizing from the drill location, and (iii) performing certain pre‑operating activities, including rig preparation activities or equipment modifications required for the contract. We recognize revenues earned under our drilling contracts based on variable dayrates, which range from a full operating dayrate to lower rates or zero rates for periods when drilling operations are interrupted or restricted, based on the specific activities we perform during the contract on an hourly, or more frequent, basis. Such dayrate consideration is attributed to the distinct time period to which it relates within the contract term, and therefore, is recognized as we perform the services. We recognize reimbursement revenues and the corresponding costs as we provide the customer‑requested goods and services, when such reimbursable costs are incurred while performing drilling operations. Prior to performing drilling operations, we may receive pre‑operating revenues, on either a fixed lump‑sum or variable dayrate basis, for mobilization, contract preparation, customer‑requested goods and services or capital upgrades, which we recognize on a straight‑line basis over the estimated firm contract period. We recognize losses for loss contracts as such losses are incurred. We recognize revenues for demobilization or from contract terminations as we fulfill our obligations and all contingencies have been resolved. The duration of our performance obligation varies by contract. At September 30, 2018, the expected remaining duration of our drilling contracts extends through February 2028, excluding unexercised options. In the three and nine months ended September 30, 2018, we recognized revenues of $54 million and $147 million, respectively, for performance obligations satisfied in previous periods, primarily related to our customer’s termination of the contract for Discoverer Clear Leader , effective November 2017, and certain revenues recognized on a cash basis. We have taken the optional exemption that permits us to exclude disclosure of the estimated transaction price related to the variable portion of unsatisfied performance obligations at the end of the reporting period, as our transaction price is based on a single performance obligation consisting of a series of distinct hourly, or more frequent, periods, the variability of which will be resolved at the time of the future services. To obtain contracts with our customers, we incur costs to prepare a rig for contract and deliver or mobilize a rig to the drilling location. We defer pre‑operating costs, such as contract preparation and mobilization costs, and recognize such costs on a straight‑line basis, consistent with the general pace of activity, in operating and maintenance costs over the estimated firm period of drilling. In the three and nine months ended September 30, 2018, we recognized costs of $14 million and $36 million, respectively, associated with pre‑operating costs for contracts with customers. In the three and nine months ended September 30, 2017, we recognized costs of $11 million and $35 million, respectively, associated with pre‑operating costs for contracts with customers. At September 30, 2018 and December 31, 2017, the unrecognized pre‑operating costs to obtain contracts was $10 million and $18 million, respectively, recorded in other assets. Disaggregation —In the three and nine months ended September 30, 2018 and 2017, we recognized revenues as follows (in millions): Three months ended September 30, 2018 Three months ended September 30, 2017 U.S. U.K. Norway Brazil Other Total U.S. U.K. Norway Brazil Other Total Ultra-deepwater floaters $ 396 $ — $ — $ 1 $ 86 $ 483 $ 368 $ — $ — $ 39 $ 116 $ 523 Harsh environment floaters — 37 174 — 54 265 8 62 15 — 33 118 Deepwater floaters — — — 25 11 36 — — — 24 11 35 Midwater floaters — 10 — — 9 19 — 8 — — 96 104 High-specification jackups — — — — 13 13 — — — — 28 28 Total revenues $ 396 $ 47 $ 174 $ 26 $ 173 $ 816 $ 376 $ 70 $ 15 $ 63 $ 284 $ 808 Nine months ended September 30, 2018 Nine months ended September 30, 2017 U.S. U.K. Norway Brazil Other Total U.S. U.K. Norway Brazil Other Total Ultra-deepwater floaters $ 1,162 $ — $ — $ 1 $ 168 $ 1,331 $ 1,167 $ — $ — $ 198 $ 244 $ 1,609 Harsh environment floaters — 88 467 — 166 721 8 197 54 — 89 348 Deepwater floaters — — — 74 32 106 — — — 73 33 106 Midwater floaters — 30 — — 27 57 — 22 — — 114 136 High-specification jackups — — — — 55 55 — 33 — — 112 145 Total revenues $ 1,162 $ 118 $ 467 $ 75 $ 448 $ 2,270 $ 1,175 $ 252 $ 54 $ 271 $ 592 $ 2,344 Contract liabilities —We recognize contract liabilities, recorded in other current liabilities and other long-term liabilities, for mobilization, contract preparation and capital upgrades using the straight‑line method over the remaining contract term. Contract liabilities for our contracts with customers were as follows (in millions): September 30, January 1, 2018 2018 Deferred contract revenues, recorded in other current liabilities $ 90 $ 203 Deferred contract revenues, recorded in other long-term liabilities 408 422 Total contract liabilities $ 498 $ 625 Significant changes in contract liabilities were as follows (in millions): Nine months ended September 30, 2018 Total contract liabilities, beginning of period 625 Decrease due to recognition of revenues for goods and services (192) Increase due to goods and services transferred over time 65 Total contract liabilities, end of period $ 498

Drilling Fleet

Drilling Fleet	9 Months Ended
	Sep. 30, 2018
Drilling Fleet
Drilling Fleet	Note 6—Drilling Fleet Construction work in progress —For the nine months ended September 30, 2018 and 2017, the changes in our construction work in progress, including capital expenditures and other capital additions, were as follows (in millions): Nine months ended September 30, 2018 2017 Construction work in progress, beginning of period $ 1,392 $ 2,171 Capital expenditures Newbuild construction program 64 299 Other equipment and construction projects 76 87 Total capital expenditures 140 386 Changes in accrued capital additions (6) (22) Construction work in progress acquired in business combination 26 — Construction work in progress sold — (289) Property and equipment placed into service Newbuild construction program (903) — Other property and equipment (61) (66) Construction work in progress, end of period $ 588 $ 2,180 Impairments of assets held and used —During the three months ended June 30, 2017, we identified indicators that the asset groups in our contract drilling services reporting unit may not be recoverable. Such indicators included recent significant declines in commodity prices and the market value of our stock, a reduction of projected dayrates and a further extension of currently low utilization rates. As a result of our testing, we determined that the carrying amount of the midwater floater asset group was impaired. In the nine months ended September 30, 2017, we recognized a loss of $94 million ($95 million after taxes, or $0.25 per diluted share), associated with the impairment of the midwater floater asset group. We measured the fair value of this asset group by applying a combination of income and market approaches, using projected discounted cash flows and estimates of the exchange price that would be received for the assets in the principal or most advantageous markets for the assets in an orderly transaction between participants as of the measurement date. Our estimate of fair value required us to use significant unobservable inputs, representative of a Level 3 fair value measurement, including assumptions related to the future performance of our contract drilling services reporting unit, such as future commodity prices, projected demand for our services, rig availability and dayrates. Impairments of assets held for sale —During the nine months ended September 30, 2018, we announced our intent to retire in an environmentally responsible way, the ultra‑deepwater floaters Deepwater Discovery , Deepwater Frontier , Deepwater Millennium and GSF C.R. Luigs and the midwater floaters Songa Delta and Songa Trym, along with related assets. In the three and nine months ended September 30, 2018, we recognized an aggregate loss of $433 million ($0.93 per diluted share) and $981 million ($2.15 per diluted share), respectively, which had no tax effect, associated with the impairment of these assets, which we determined were impaired at the time we classified the assets as held for sale. During the nine months ended September 30, 2017, we announced our intent to retire in an environmentally responsible way, the ultra-deepwater floaters Cajun Express, Deepwater Pathfinder, GSF Jack Ryan , Sedco Energy and Sedco Express and the deepwater floater Transocean Marianas and the midwater floaters Transocean Prospect and Transocean Searcher , along with related assets. In the three months and nine months ended September 30, 2017, we recognized an aggregate loss of $1.4 billion ($3.54 per diluted share) and $1.4 billion ($3.60 per diluted share), respectively, which had no tax effect, associated with the impairment of these assets, which we determined were impaired at the time we classified the assets as held for sale. We measured the impairment of the drilling units and related equipment as the amount by which the carrying amount exceeded the estimated fair value less costs to sell. We estimated the fair value of the assets using significant other observable inputs, representative of a Level 2 fair value measurement, including indicative market values for the drilling units and related assets to be sold for scrap value. Dispositions —During the nine months ended September 30, 2018, in connection with our efforts to dispose of non‑strategic assets, we completed the sale of the ultra‑deepwater floaters Cajun Express , Deepwater Discovery , Deepwater Pathfinder , Sedco Energy and Sedco Express , the deepwater floater Transocean Marianas and the midwater floater Songa Trym , along with related assets. In the nine months ended September 30, 2018, we received aggregate net cash proceeds of $31 million and recognized an aggregate net gain of $6 million ($0.02 per diluted share), which had no tax effect, associated with the disposal of these assets. In the nine months ended September 30, 2018, we received aggregate net cash proceeds of $6 million and recognized an aggregate net loss of $6 million associated with the disposal of assets unrelated to rig sales. On May 31, 2017, we completed the sale of 10 high‑specification jackups, including GSF Constellation I, GSF Constellation II, GSF Galaxy I, GSF Galaxy II, GSF Galaxy III, GSF Monarch, Transocean Andaman, Transocean Ao Thai, Transocean Honor and Transocean Siam Driller , along with related assets, and novated the contracts relating to the construction of five high‑specification jackups, together with related assets. In the nine months ended September 30, 2017, we received aggregate net cash proceeds of $319 million and recognized an aggregate net loss of $1.6 billion ($4.08 per diluted share), which had no tax effect, associated with the disposal of these assets. Following the completion of the sale, we agreed to continue to operate three of these high‑specification jackups through completion or novation of the drilling contracts, one of which we continue to operate as of September 30, 2018. In the three and nine months ended September 30, 2018, our operating results included income of $10 million and $42 million, respectively, before taxes, associated with the high specification jackups that we continued to operate during the period. In the three and nine months ended September 30, 2017, excluding our loss on the disposal of these assets, our operating results included income of $19 million and $46 million, respectively, before taxes, associated with the high‑specification jackup asset group. During the nine months ended September 30, 2017, we also completed the sale of the midwater floater GSF Rig 140, along with related assets. In the nine months ended September 30, 2017, we received aggregate net cash proceeds of $3 million and recognized an aggregate net gain of $2 million associated with the disposal of this asset. In the three and nine months ended September 30, 2017, we received aggregate net cash proceeds of $1 million and $8 million, respectively, and recognized an aggregate net loss of $9 million and $8 million, respectively, associated with the disposal of assets unrelated to rig sales. Assets held for sale —At September 30, 2018, the aggregate carrying amount of our assets held for sale, including the ultra‑deepwater floaters Deepwater Frontier , Deepwater Millennium and GSF C.R. Luigs and the midwater floater Songa Delta , along with related assets, was $26 million, recorded in other current assets. At December 31, 2017, the aggregate carrying amount of our assets held for sale, including the ultra‑deepwater floaters Cajun Express, Deepwater Pathfinder, Sedco Energy and Sedco Express and the deepwater floater Transocean Marianas , along with related assets, was $22 million, recorded in other current assets.

Goodwill

Goodwill	9 Months Ended
	Sep. 30, 2018
Goodwill
Goodwill	Note 7—Goodwill Impairment —We conduct goodwill impairment testing annually and when events occur or circumstances change that would more likely than not reduce the fair value of our reporting unit below its carrying amount. During the three months ended June 30, 2018, we classified as held for sale and impaired three ultra‑deepwater floaters (see Note 6—Drilling Fleet). We identified the impairment of these assets included in our single contract drilling services reporting unit as a trigger to test the recoverability of goodwill. As a result, we performed an interim goodwill impairment test as of June 30, 2018, and we determined that the goodwill associated with our contract drilling services reporting unit was fully impaired. In the nine months ended September 30, 2018, we recognized a loss of $46 2 million ($1.02 per diluted share), which had no tax effect, associated with the impairment of the full balance of our goodwill. We estimated the fair value of the contract drilling services reporting unit using the income approach. Our estimate of fair value required us to use significant unobservable inputs, representative of a Level 3 fair value measurement, including assumptions related to the future performance of the reporting unit, such as future commodity prices, projected demand for our services, rig availability and dayrates.

Debt

Debt	9 Months Ended
	Sep. 30, 2018
Debt
Debt	Note 8—Debt Overview Outstanding debt —The aggregate principal amounts and aggregate carrying amounts, net of debt‑related balances, including unamortized discounts, premiums, issue costs and fair value adjustments of our debt, were as follows (in millions): Principal amount Carrying amount September 30, December 31, September 30, December 31, 2018 2017 2018 2017 Eksportfinans Loan due January 2018 $ — $ 26 $ — $ 26 6.50% Senior Notes due November 2020 286 286 288 288 6.375% Senior Notes due December 2021 328 328 327 327 5.52% Senior Secured Notes due May 2022 303 362 299 356 3.80% Senior Notes due October 2022 411 506 408 502 0.50% Exchangeable Bonds due January 2023 863 — 862 — 9.00% Senior Notes due July 2023 1,250 1,250 1,220 1,216 5.875% Senior Secured Notes due January 2024 750 — 734 — 7.75% Senior Secured Notes due October 2024 510 540 498 526 6.25% Senior Secured Notes due December 2024 531 562 520 549 6.125% Senior Secured Notes due August 2025 600 — 587 — 7.50% Senior Notes due January 2026 750 750 742 742 7.45% Notes due April 2027 88 88 86 86 8.00% Debentures due April 2027 57 57 57 57 7.00% Notes due June 2028 300 300 307 307 Capital lease contract due August 2029 519 541 519 541 7.50% Notes due April 2031 588 588 585 585 6.80% Senior Notes due March 2038 1,000 1,000 991 991 7.35% Senior Notes due December 2041 300 300 297 297 Total debt 9,434 7,484 9,327 7,396 Less debt due within one year Eksportfinans Loan due January 2018 — 26 — 26 5.52% Senior Secured Notes due May 2022 83 79 81 77 5.875% Senior Secured Notes due January 2024 83 — 79 — 7.75% Senior Secured Notes due October 2024 60 60 58 57 6.25% Senior Secured Notes due December 2024 62 62 60 60 6.125% Senior Secured Notes due August 2025 66 — 63 — Capital lease contract due August 2029 31 30 31 30 Total debt due within one year 385 257 372 250 Total long-term debt $ 9,049 $ 7,227 $ 8,955 $ 7,146 Scheduled maturities —At September 30, 2018, the scheduled maturities of our debt were as follows (in millions): Total Twelve months ending September 30, 2019 $ 385 2020 392 2021 685 2022 681 2023 2,838 Thereafter 4,453 Total principal amount of debt 9,434 Total debt-related balances, net (107) Total carrying amount of debt $ 9,327 Interest rate adjustments —The interest rates for certain of our notes are subject to adjustment from time to time upon a change to the credit rating of our non‑credit enhanced senior unsecured long‑term debt. As of September 30, 2018, the interest rate in effect for the 6.375% senior notes due December 2021, 3.80% senior notes due October 2022 and the 7.35% senior notes due December 2041 was 8.375 percent, 5.80 percent and 9.35 percent, respectively. Secured Credit Facility —In June 2018, we entered into a bank credit agreement, which established a $1.0 billion secured revolving credit facility (the “Secured Credit Facility”), which is scheduled to expire on the earlier of (i) June 22, 2023 and (ii) if greater than $300 million aggregate principal amount of our 9.00% Senior Notes due July 2023 remain outstanding in April 2023, such date. The Secured Credit Facility is guaranteed by Transocean Ltd. and certain subsidiaries. The Secured Credit Facility is initially secured by, among other things, a lien on the ultra‑deepwater floaters Deepwater Asgard, Deepwater Invictus and Discoverer Inspiration and the harsh environment floaters Transocean Barents and Transocean Spitsbergen . The Secured Credit Facility contains covenants that, among other things, include maintenance of certain guarantee and collateral coverage ratios, a maximum debt to capitalization ratio of 0.60 to 1.00 and minimum liquidity of $500 million. The Secured Credit Facility also restricts the ability of Transocean Ltd. and certain of our subsidiaries to, among other things, merge, consolidate or otherwise make changes to the corporate structure, incur liens, incur additional indebtedness, enter into transactions with affiliates and pay dividends and other distributions. We may borrow under the Secured Credit Facility at either (1) the reserve adjusted London interbank offered rate plus a margin (the “Secured Credit Facility Margin”), which ranges from 2.625 percent to 3.25 percent based on the credit rating of the Secured Credit Facility, or (2) the base rate specified in the credit agreement plus the Secured Credit Facility Margin, minus one percent per annum. Throughout the term of the Secured Credit Facility, we pay a facility fee on the amount of the underlying commitment which ranges from 0.375 percent to 1.00 percent based on the credit rating of the Secured Credit Facility. At September 30, 2018, based on the credit rating of the Secured Credit Facility on that date, the Secured Credit Facility Margin was 2.75 percent and the facility fee was 0.50 percent. At September 30, 2018, we had no borrowings outstanding, $24 million of letters of credit issued, and we had $1.0 billion of available borrowing capacity under the Secured Credit Facility. See Note 12—Commitments and Contingencies—Global Marine litigation. Former Credit Facility —In June 2014, we entered into an amended and restated bank credit agreement, which established a $3.0 billion unsecured five‑year revolving credit facility, which was scheduled to expire on June 28, 2019 (the “Former Credit Facility”). In June 2018, we terminated the Former Credit Facility and recognized a loss of $1 million associated with the termination. Debt issuances Senior secured notes —On July 13, 2018, we issued $750 million aggregate principal amount of 5.875% senior secured notes due January 2024 (the “5.875% Senior Secured Notes”) and received aggregate cash proceeds of $733 million, net of discount and issue costs. In connection with the issuance of such notes, we were required to deposit $63 million in restricted cash accounts to satisfy debt service and reserve requirements. We are required to pay semiannual installments of principal and interest on the 5.875% Senior Secured Notes, beginning January 15, 2019. The 5.875% Senior Secured Notes are secured by the assets and earnings associated with the harsh environment floaters Transocean Enabler and Transocean Encourage and the equity of the wholly owned subsidiaries that own or operate the collateral rigs. On July 20, 2018, we issued $600 million aggregate principal amount of 6.125% senior secured notes due August 2025 (the “6.125% Senior Secured Notes” and, together with the 5.875% Senior Secured Notes, the “2018 Senior Secured Notes”), and we received aggregate cash proceeds of $586 million, net of discount and issue costs. In connection with the issuance of such notes, we were required to deposit $51 million in restricted cash accounts to satisfy debt service and reserve requirements. We are required to pay semiannual installments of principal and interest on the 6.125% Senior Secured Notes, beginning February 1, 2019. The 6.125% Senior Secured Notes are secured by the assets and earnings associated with the ultra‑deepwater floater Deepwater Pontus and the equity of the wholly owned subsidiaries that own or operate the collateral rig. We may redeem all or a portion of the 2018 Senior Secured Notes at a price equal to 100 percent of the aggregate principal amount plus a make‑whole provision. We will be required to redeem the notes at a price equal to 100 percent of the aggregate principal amount without a make‑whole provision, upon the occurrence of certain events related to the collateral rigs and the related drilling contracts. The indentures that govern the 2018 Senior Secured Notes each contain covenants that, among other things, limit the ability of our subsidiaries that own or operate the collateral rigs to declare or pay dividends to their affiliates. The indentures also impose a maximum collateral rig leverage ratio (the “Maximum Collateral Ratio”), represented by the net earnings of the respective collateral rigs relative to the respective debt balance, that changes over the term of the notes. Through March 31, 2020, the Maximum Collateral Ratio under the indenture for the 6.125% Senior Secured Notes is 5.75 to 1.00. Through March 31, 2019, the Maximum Collateral Ratio under the indenture for the 5.875% Senior Secured Notes is 6.00 to 1.00. Exchangeable bonds —In connection with the Songa acquisition transactions, we issued $863 million aggregate principal amount of Exchangeable Bonds, as partial consideration for the Songa shares and as consideration for refinancing certain Songa indebtedness. Transocean Inc., our wholly owned direct subsidiary, is the issuer of the Exchangeable Bonds, for which Transocean Ltd. has provided a full and unconditional guarantee. We are required to pay interest on the Exchangeable Bonds semiannually, beginning on July 30, 2018. The Exchangeable Bonds may be converted at any time prior to the maturity date at an exchange rate of 97.29756 shares per $1,000 note, equivalent to a conversion price of $10.28 per share, subject to adjustment upon the occurrence of certain events. Holders of Exchangeable Bonds may require us to repurchase all or a portion of such holder’s Exchangeable Bonds upon the occurrence of certain events. The aggregate fair value of the Exchangeable Bonds, measured as of the issuance date, was $1.04 billion, which represented a substantial premium of $172 million above par, and we recorded such premium to additional paid‑in capital. We estimated the fair value using significant other observable inputs, representative of a Level 2 fair value measurement, including the terms and credit spreads for the instruments. 5.52% Senior Secured Notes —On May 5, 2017, we issued $410 million aggregate principal amount of 5.52% senior secured notes due May 2022, and in the nine months ended September 30, 2017, we received aggregate cash proceeds of $403 million, net of issue costs. See Note 15—Subsequent Event. Debt assumptions and repayments Senior Secured Term Loans —In connection with the Songa acquisition, we assumed the rights and obligations under credit agreements establishing two senior secured term loan facilities (the “Senior Secured Term Loans”). The credit agreements contained change of control clauses, for which we received waivers from the lenders that were scheduled to expire on August 31, 2018. In the three months ended September 30, 2018, we made an aggregate cash payment of $1.4 billion to repay the borrowings under the Senior Secured Term Loans and recognized an aggregate loss of $1 million associated with the termination of the underlying credit agreements of such loans. Junior Secured Bonds —In connection with the Songa acquisition, we assumed the rights and obligations under a subscription agreement establishing a junior secured bond facility (the “Junior Secured Bonds”). The subscription agreement contained a change of control clause, for which we received waivers from the lenders that were scheduled to expire on August 31, 2018. On February 12, 2018, we served notice of our intent to call the Junior Secured Bonds. On August 20, 2018, we made an aggregate cash payment of $171 million to repay the borrowings under the Junior Secured Bonds and terminated the underlying subscription agreement. Other debt —In connection with the Songa acquisition, we assumed the indebtedness related to two bond loans (together, the “Bond Loans”), previously publicly traded on the Oslo stock exchange. On the acquisition date, the Bond Loans had an aggregate principal amount of NOK 337 million, equivalent to $44 million. On March 14, 2018, we made a cash payment of NOK 345 million, equivalent to $44 million, to repay the Bond Loans. We also assumed the rights and obligations under a credit agreement, which was due to expire March 31, 2018, for a secured borrowing facility. On February 2, 2018, we made a cash payment of $23 million to repay the borrowings outstanding under the secured borrowing facility and terminated the underlying credit agreement. Debt retirements Repurchases and repayments —During the nine months ended September 30, 2018 and 2017, we repurchased in the open market debt securities with aggregate principal amounts as follows (in millions): Nine months ended September 30, 2018 2017 2.50% Senior Notes due October 2017 $ — $ 62 6.00% Senior Notes due March 2018 — 35 7.375% Senior Notes due April 2018 — 1 6.50% Senior Notes due November 2020 — 9 6.375% Senior Notes due December 2021 — 7 3.80% Senior Notes due October 2022 95 33 Aggregate principal amount retired $ 95 $ 147 Aggregate cash payment $ 95 $ 147 In the three and nine months ended September 30, 2018, we recognized an aggregate net loss of less than $1 million associated with the retirement of repurchased or repaid debt. In the nine months ended September 30, 2017, we recognized an aggregate net loss of $1 million associated with the retirement of such repurchased debt. Tender offers —In July 2017, we completed cash tender offers to purchase up to $1.5 billion aggregate principal amount of certain notes (the “2017 Tendered Notes”). We received valid tenders from holders of aggregate principal amounts of the 2017 Tendered Notes as follows (in million): Nine months ended September 30, 2017 2.50% Senior Notes due October 2017 $ 271 6.00% Senior Notes due March 2018 400 7.375% Senior Notes due April 2018 128 6.50% Senior Notes due November 2020 207 6.375% Senior Notes due December 2021 213 Aggregate principal amount retired $ 1,219 Aggregate cash payment $ 1,269 In the three and nine months ended September 30, 2017, we recognized an aggregate net loss of $1 million and $48 million, respectively, associated with the retirement of such validly tendered debt.

Derivative Instruments

Derivative Instruments	9 Months Ended
	Sep. 30, 2018
Derivative Instruments
Derivatives instruments	Note 9—Derivative Instruments Forward exchange contracts —At September 30, 2018, we held undesignated forward exchange contracts, extending through June 2019, with an aggregate notional payment amount of $113 million and an aggregate notional receive amount of NOK 900 million, representing a weighted average exchange rate of NOK 7.96 to $1. In the three and nine months ended September 30, 2018, we recognized a loss of $3 million, recorded in other, net, associated with the forward exchange contracts. At September 30, 2018, the undesignated forward exchange contracts represented a liability with a carrying amount of $2 million, recorded in other current liabilities. In connection with the Songa acquisition, we acquired certain undesignated forward exchange contracts that extended through May 2018 and represented an economic hedge to reduce the variability of cash expenditures denominated in Norwegian kroner. On the acquisition date, the aggregate fair value of the forward exchange contracts represented an asset of $4 million. During the nine months ended September 30, 2018, we settled the remaining forward exchange contracts upon expiration. In the nine months ended September 30, 2018, we recognized a loss of $1 million, recorded in other, net, associated with the forward exchange contracts. Interest rate swaps —In connection with the Songa acquisition, we acquired interest rate swaps, which were previously designated but no longer qualified as a cash flow hedge, to reduce the variability of cash interest payments associated with the variable rate borrowings under the Senior Secured Term Loans, which we repaid in the three months ended September 30, 2018. On the acquisition date, the aggregate fair value of the interest rate swaps represented an asset of $14 million. In July and August 2018, we received aggregate cash proceeds of $18 million in connection with the settlement and termination of the interest rate swaps. In the three and nine months ended September 30, 2018, we recognized a loss of $1 million and a gain of $4 million, respectively, recorded in other, net, associated the interest rate swaps. Currency swaps —In connection with the Songa acquisition, we acquired currency swaps, which were previously designated as a cash flow hedge, to reduce the variability of cash interest payments and the final cash principal payment associated with the Bond Loans resulting from the changes in the U.S. dollar to Norwegian krone exchange rate. On the acquisition date, the aggregate fair value of the currency swaps represented a liability of $81 million. In February 2018, we made an aggregate cash payment of $92 million in connection with the settlement and termination of the currency swaps. In the nine months ended September 30, 2018, we recognized a loss of $11 million, recorded in other, net., associated with the currency swaps.

Income Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2018
Income Taxes
Income Taxes	Note 10—Income Taxes Tax provision and 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. Our provision for income taxes is based on the tax laws and rates applicable in the jurisdictions in which we operate and earn income. In the nine months ended September 30, 2018 and 2017, our estimated effective tax rate, excluding discrete items, was (15.6) percent and 64.2 percent, respectively, based on estimated annual income or loss before income taxes. In the nine months ended September 30, 2018, compared to the nine months ended September 30, 2017, our effective tax rate decreased primarily due to changes in the relative blend of income from operations in certain jurisdictions and the loss before income taxes and the increased tax expense as a result of the U.S. base erosion and anti‑abuse tax (“BEAT”). We consider the tax effect, if any, of the excluded items noted, as well as settlements of prior year tax estimates to be discrete period tax expenses or benefits. In the nine months ended September 30, 2018 and 2017, the effect of the various discrete period tax items was a net tax expense of $91 million and a net tax benefit of $57 million, respectively. In the nine months ended September 30, 2018, such discrete items were primarily related to the U. S. transition tax on non‑U.S. earnings. In the nine months ended September 30, 2017, such discrete items were largely related to the tax benefit of changes in unrecognized tax benefits associated with tax positions taken in prior years, valuation allowances on deferred tax assets for foreign tax credits not expected to be realized and deductions related to resolution of certain litigation matters related to the Macondo well incident. For the nine months ended September 30, 2018 and 2017, these discrete tax items, coupled with the excluded income and expense items noted above, resulted in an effective tax rate of (7.2 ) p ercent and (3.6) percent, respectively, based on income or loss before income tax expense. During the three months ended September 30, 2018, our U.S. valuation allowance increased by $91 million due to the deferred tax benefit recognized from the impairment of GSF C.R. Luigs . U.S. tax reform —In December 2017, the U.S. enacted the 2017 Tax Act, which included prospective changes beginning in 2018, including a BEAT, a global intangible low‑taxed income (“GILTI”) tax, additional limitations on the deductibility of executive compensation, limitations on the deductibility of interest and repeal of the domestic manufacturing deduction. Effective January 1, 2018, we elected to treat any potential GILTI inclusions as a period cost, and we have also evaluated our bareboat charter structure and have concluded that the current structure of our U.S. operations is subject to BEAT. We have reflected the estimated impact of this tax in our provision for the nine months ended September 30, 2018. A significant portion of our BEAT liability is contractually protected due to a change in law provision in certain drilling contracts. Transition tax on non‑U.S. earnings —The 2017 Tax Act imposes a one‑time transition tax on certain unremitted earnings and profits of our non‑U.S. subsidiaries. At December 31, 2017, we did not have the necessary information available, prepared and analyzed to develop a reasonable estimate of the transition tax. In the nine months ended September 30, 2018, we recorded income tax expense of $104 million for estimated transition taxes and an income tax benefit of $17 million for the estimated effect on the utilization of foreign tax credits. Due to the number of years and complexity of determining amounts and composition of earnings and profits held in cash and other assets by the non‑U.S. subsidiaries of our U.S. subsidiaries subject to the transition tax, the determination of the transition tax requires further analysis. The ultimate effect of our analysis may result in changes to our current estimate. We have not yet made any changes to our assertion that the unremitted earnings of our non‑U.S. subsidiaries will be indefinitely reinvested. We will complete our evaluation within the measurement period provided by Staff Accounting Bulletin No. 118. 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 2010. Our tax returns in the major jurisdictions in which we operate, other than Brazil, as mentioned below, are generally subject to examination for periods ranging from three to six years. We have agreed to extensions beyond the statute of limitations in two major jurisdictions for up to 20 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 timing or the outcome of these proceedings, we do not expect the ultimate liability to have a material adverse effect on our condensed consolidated statement of financial position or results of operations, although it may have a material adverse effect on our condensed consolidated statement of cash flows. Brazil tax investigations —In December 2005, the Brazilian tax authorities began issuing tax assessments with respect to our tax returns for the years 2000 through 2004. In January 2008, we filed a protest letter with the Brazilian tax authorities for these tax assessments, and we are currently engaged in the appeals process. In May 2014, the Brazilian tax authorities issued an additional tax assessment for tax years 2009 and 2010, and in June 2014, we filed protests with the Brazilian tax authorities for these tax assessments. In September 2018, a portion of one of the cases was favorably closed. As of September 30, 2018, the remaining aggregate tax assessment was for BRL 946 million, equivalent to $234 million, including penalties and interest. We believe our returns are materially correct as filed, and we are vigorously contesting these assessments. An unfavorable outcome on these proposed assessments could result in a material adverse effect on our condensed consolidated statement of financial position, results of operations or cash flows. Other tax matters —We conduct operations through our various subsidiaries in countries throughout the world. Each country has its own tax regimes with varying nominal rates, deductions and tax attributes. From time to time, we may identify changes to previously evaluated tax positions that could result in adjustments to our recorded assets and liabilities. Although we are unable to predict the outcome of these changes, we do not expect the effect, if any, resulting from these adjustments to have a material adverse effect on our condensed consolidated statement of financial position, results of operations or cash flows.

Loss Per Share

Loss Per Share	9 Months Ended
	Sep. 30, 2018
Loss Per Share
Loss Per Share	Note 11—Loss Per Share The numerator and denominator used for the computation of basic and diluted per share loss were as follows (in millions, except per share data): Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Basic Diluted Basic Diluted Basic Diluted Basic Diluted Numerator for loss per share Net loss attributable to controlling interest $ (409) $ (409) $ (1,417) $ (1,417) $ (1,754) $ (1,754) $ (3,016) $ (3,016) Undistributed earnings allocable to participating securities — — — — — — — — Net loss available to shareholders $ (409) $ (409) $ (1,417) $ (1,417) $ (1,754) $ (1,754) $ (3,016) $ (3,016) Denominator for loss per share Weighted-average shares outstanding 463 463 391 391 454 454 391 391 Effect of share-based awards and other equity instruments — — — — — — — — Weighted-average shares for per share calculation 463 463 391 391 454 454 391 391 Per share loss $ (0.88) $ (0.88) $ (3.62) $ (3.62) $ (3.86) $ (3.86) $ (7.72) $ (7.72) In the three and nine months ended September 30, 2018, we excluded from the calculation 10.7 million share‑based awards since the effect would have been anti‑dilutive. In the three and nine months ended September 30, 2017, we excluded from the calculation 5.6 million and 4.7 million share‑based awards, respectively, since the effect would have been anti‑dilutive. In the three and nine months ended September 30, 2018, we excluded from the calculation 84.0 million and 74.9 million shares issuable upon conversion of the Exchangeable Bonds, respectively, since the effect would have been anti‑dilutive.

Commitments and Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2018
Commitments and Contingencies
Commitments and Contingencies	Note 12—Commitments and Contingencies Macondo well incident commitments and contingencies 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 off the coast of Louisiana. At the time of the explosion, Deepwater Horizon was contracted to an affiliate of BP plc (together with its affiliates, “BP”). Following the incident, we have been subject to civil and criminal claims, as well as causes of action, fines and penalties by local, state and federal governments. Litigation commenced shortly after the incident, and most claims against us were consolidated by the U.S. Judicial Panel on Multidistrict Litigation and transferred to the U.S. District Court for the Eastern District of Louisiana (the “MDL Court”). A significant portion of the contingencies arising from the Macondo well incident has now been resolved or is pending release of funds from escrow (see “—PSC Settlement Agreement”). As for any actions not resolved by our previous settlements, including any claims by individuals who opted out of the settlement agreement that we and the Plaintiff Steering Committee (the “PSC”) filed with the MDL Court in May 2015 (the “PSC Settlement Agreement”), we will vigorously defend those claims and pursue any and all defenses available. We have recognized a liability for the remaining estimated loss contingencies associated with litigation resulting from the Macondo well incident that we believe are probable and for which a reasonable estimate can be made. At September 30, 2018 and December 31, 2017, the liability for estimated loss contingencies that we believe are probable and for which a reasonable estimate can be made was $217 million and $219 million, respectively, recorded in other current liabilities, the majority of which is related to our settlement with the PSC. Plea Agreement —Pursuant to the plea agreement (the “Plea Agreement”), one of our subsidiaries pled guilty to one misdemeanor count of negligently discharging oil into the U.S. Gulf of Mexico, in violation of the Clean Water Act, for which our subsidiary is no longer subject to probation. We also agreed to make an aggregate cash payment of $ 400 million, including a criminal fine and certain cash contributions payable in scheduled installments. In the nine months ended September 30, 2017, we made a cash payment of $60 million, representing the final installment for our obligations under the Plea Agreement. PSC Settlement Agreement —On May 29, 2015, together with the PSC, we filed the PSC Settlement Agreement with the MDL Court for approval. Through the PSC Settlement Agreement, we agreed to pay a total of $212 million, plus up to $25 million for partial reimbursement of attorneys’ fees, to be allocated between two classes of plaintiffs as follows: (1) 72.8 percent to private plaintiffs, businesses, and local governments who could have asserted punitive damages claims against us under general maritime law and (2) 27.2 percent to private plaintiffs who previously settled economic damages claims against BP and were assigned certain claims BP had made against us. In exchange for these payments, each of the classes agreed to release all respective claims it has against us. Thirty claimants elected to opt out of the PSC Settlement Agreement. In June 2016 and August 2015, we made a cash deposit of $25 million and $212 million, respectively, into escrow accounts established by the MDL Court for the settlement. On February 15, 2017, the MDL Court entered a final order and judgement approving the PSC Settlement Agreement, which is no longer subject to appeal. In November 2017, the MDL Court released $25 million from the escrow accounts for payment of attorneys’ fees. We expect the remaining funds to be released in three installments, the last of which is scheduled to be in March 2019. At September 30, 2018 and December 31, 2017, the aggregate cash balance in escrow accounts was $214 million and $212 million, respectively, recorded in restricted cash accounts and investments. Other legal proceedings Asbestos litigation —In 2004, several of our subsidiaries were named, along with numerous other unaffiliated defendants in complaints filed in the Circuit Courts of the State of Mississippi, and in 2014, a group of similar complaints were filed in Louisiana. The plaintiffs, former employees of some of the defendants, generally allege that the defendants used or manufactured asbestos containing drilling mud additives for use in connection with drilling operations, claiming 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, but the court‑appointed special master has ruled that a Jones Act employer defendant, such as us, cannot be sued for punitive damages. At September 30, 2018, nine plaintiffs have claims pending in Louisiana, in which we have or may have an interest. We intend to defend these lawsuits vigorously, although we can provide no assurance as to the 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 condensed consolidated statement of financial position, results of operations or cash flows. One of our subsidiaries has been named as a defendant, along with numerous other companies, in lawsuits arising out of the subsidiary’s manufacture and sale of heat exchangers, and involvement in the construction and refurbishment of major industrial complexes alleging bodily injury or personal injury as a result of exposure to asbestos. As of September 30, 2018, the subsidiary was a defendant in approximately 141 lawsuits with a corresponding number of plaintiffs. For many of these lawsuits, we have not been provided 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 operating assets of the subsidiary were sold in 1989. In September 2018, the subsidiary and certain insurers agreed to a settlement of outstanding disputes that leaves the subsidiary with funding, including cash, annuities and coverage in place settlement, that we believe will be sufficient to respond to both the current lawsuits as well as future lawsuits of a similar nature. While we cannot predict or provide assurance as to the outcome of these matters, we do not expect the ultimate liability, if any, resulting from these claims to have a material adverse effect on our condensed consolidated statement of financial position, results of operations or cash flows. Nigerian Cabotage Act litigation —In October 2007, three of our subsidiaries were each served a Notice and Demand from the Nigeria Maritime Administration and Safety Agency, imposing a two percent surcharge on the value of all contracts performed by us in Nigeria pursuant to the Coastal and Inland Shipping (Cabotage) Act 2003 (the “Cabotage Act”). Our subsidiaries each filed an originating summons in the Federal High Court in Lagos challenging the imposition of this surcharge on the basis that the Cabotage Act and associated levy is not applicable to drilling rigs. The respondents challenged the competence of the suits on several procedural grounds. The court upheld the objections and dismissed the suits. In December 2010, our subsidiaries filed a new joint Cabotage Act suit. While we cannot predict or provide assurance as to the outcome of these proceedings, we do not expect the proceedings to have a material adverse effect on our condensed consolidated statement of financial position, results of operations or cash flows. Global Marine litigation —On November 28, 2017, Wilmington Trust Company, in its capacity as trustee, filed a lawsuit in the Supreme Court of the State of New York, County of New York, against Global Marine Inc. (“Global Marine”), one of our wholly owned, indirect subsidiaries, seeking a declaratory judgment that Global Marine is in default under the indenture governing its $300 million of outstanding 7.00% Notes due June 2028. We disagree with the assertions in the lawsuit and believe that Global Marine is in compliance with the indenture and has meritorious defenses against these allegations, although it can make no assurance regarding the outcome of the lawsuit, including the actual amount that would be due in the event that the lawsuit is successful. The notes are neither guaranteed by, nor recourse to, Transocean Ltd. or our other subsidiaries. The claimants seek payment prior to the scheduled maturity of the principal amount of notes outstanding and accrued but unpaid interest as well as make‑whole amounts under the indenture. In addition, the acceleration of the amounts due under the indenture could, absent our payment of the amounts due or otherwise staying any judgment therefrom, result in an event of default under our currently undrawn Secured Credit Facility. We intend to vigorously defend the lawsuit. While we cannot predict or provide assurance as to the outcome of these proceedings, we do not expect the proceedings to have a material adverse effect on our condensed consolidated statement of financial position, results of operations or cash flows. Nigerian customer arbitration —One of our customers in Nigeria owes us approximately $80 million for drilling services performed in 2014 and 2015. The customer has not disputed the services rendered and we have remained engaged in discussions with the customer about collection of this overdue balance. In September 2018, we notified the customer of our intentions to enter into arbitration. We intend to vigorously pursue full recovery of this receivable. While we cannot predict or provide assurance as to its outcome, we do not expect it to have a material adverse effect on our condensed consolidated statement of financial position, results of operations or cash flows. Other matters —We are involved in various tax matters, including certain tax assessments originally issued in 2006 on equipment imported into Rio de Janeiro, Brazil, various regulatory matters, and a number of claims and lawsuits, asserted and unasserted, 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 condensed 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, threatened, or possible litigation or liability. We can provide no assurance that our beliefs or expectations as to the outcome or effect of any tax, regulatory, 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 Environmental Protection Agency (the “EPA”) and the Department of Justice to settle our potential liabilities for this site by agreeing to perform the remaining remediation required by the EPA. 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, which is now a part of the San Gabriel Valley, Area 3, Superfund site. We were also advised that one or more of our subsidiaries that formerly owned and operated the site would likely be named by the EPA as PRPs. The current property owner, an unrelated party, performed the required testing and detected no contaminants. 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 (a) the actual responsibility attributed to us and the other PRPs at the site, (b) appropriate investigatory or remedial actions and (c) 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 (i) the volume and nature of material, if any, contributed to the site for which we are responsible, (ii) the number of other PRPs and their financial viability and (iii) 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 that are likely to be asserted, is adequately accrued and should not have a material effect on our condensed consolidated statement of financial position, results of operations or cash flows.

Equity

Equity	9 Months Ended
	Sep. 30, 2018
Equity
Equity	Note 13—Equity Redeemable noncontrolling interest —Until June 11, 2018, we owned a 65 percent interest in Angola Deepwater Drilling Company Ltd. (“ADDCL”), a Cayman Islands company and variable interest entity for which we concluded that we were the primary beneficiary. Angco Cayman Limited (“Angco Cayman”) owned the remaining a 35 percent interest in ADDCL. Under the terms of ADDCL’s governing documents, Angco Cayman had the right to require us to purchase its interest in ADDCL for cash, and accordingly, we presented the carrying amount of Angco Cayman’s ownership interest as redeemable noncontrolling interest on our consolidated balance sheets. We also had the right under ADDCL’s governing documents to require Angco Cayman to sell us its interest, and we exercised that right. On June 11, 2018, pursuant to a settlement requiring no cash payment, we acquired the interests in ADDCL not previously owned by us, and ADDCL became our wholly owned subsidiary. In connection with the acquisition, we reclassified the $53 million aggregate carrying amount of the redeemable noncontrolling interest to additional paid‑in capital. At December 31, 2017, the carrying amount of the assets and liabilities of ADDCL, after eliminating the effect of intercompany transactions, was $716 million and $7 million, respectively. Extraordinary general meetings —On January 16, 2018, in connection with the Songa acquisition, shareholders at our extraordinary general meeting approved: (1) the issuance of up to 68.6 million Transocean Ltd. shares, (2) an amendment of our articles of association to create additional authorized share capital, (3) the election of a new director to our board of directors and (4) the issuance of consideration shares from our authorized share capital and shares issuable upon exchange of the Exchangeable Bonds. Pursuant to the Merger Agreement, we agreed to acquire all issued and outstanding shares of Ocean Rig. In connection with the acquisition, shareholders at our extraordinary general meeting, scheduled for November 29, 2018, will be asked to consider the following: (1) an amendment of our articles of association to create additional authorized share capital, (2) the issuance of up to 147.7 million Transocean Ltd. shares and (3) the deletion of the previously approved special purpose authorized share capital.

Financial Instruments

Financial Instruments	9 Months Ended
	Sep. 30, 2018
Financial Instruments
Financial Instruments	Note 14—Financial Instruments Overview —The carrying amounts and fair values of our financial instruments were as follows (in millions): September 30, 2018 December 31, 2017 Carrying Fair Carrying Fair amount value amount value Cash and cash equivalents $ 2,307 $ 2,307 $ 2,519 $ 2,519 Short-term investments — — 450 450 Restricted cash and cash equivalents 568 568 456 456 Restricted investments 7 7 33 33 Long-term debt, including current maturities 9,327 9,949 7,396 7,538 Derivative instruments, liabilities 2 2 — — We estimated the fair value of each class of financial instruments, for which estimating fair value is practicable, by applying the following methods and assumptions: Cash and cash equivalents —The carrying amount of our cash and cash equivalents represents the historical cost, plus accrued interest. Our cash equivalents are primarily invested in short‑term time deposits and money market funds. The carrying amount of our cash and cash equivalents approximates fair value because of the short maturities of the instruments. Short‑term investments —The carrying amount of our unrestricted short‑term investments represents the historical cost of the time deposits in which they are invested. The carrying amount of such short‑term investments approximates fair value because of the near‑term maturities of the instruments. Restricted cash and cash equivalents —The carrying amount of our restricted cash and cash equivalents, which are subject to restrictions due to collateral requirements, legislation, regulation or court order, approximates fair value due to the near‑term maturities of the instruments in which the restricted balances are held. At September 30, 2018, the aggregate carrying amount of such restricted cash and cash equivalents was $568 million, including $561 million and $7 million recorded in current assets and other assets, respectively. At December 31, 2017, the aggregate carrying amount of such restricted cash and cash equivalents was $456 million, including $440 million and $16 million recorded in current assets and other assets, respectively. Restricted investments —The carrying amount of our restricted investments, which are pledged for security of certain other credit arrangements, represents the amortized historical cost of the investment. The carrying amount of such restricted investments approximates fair value because of the near‑term maturities of the instruments. At September 30, 2018, the aggregate carrying amount of the restricted cash investments was $7 million, recorded in other assets. At December 31, 2017, the aggregate carrying amount of the restricted cash investments was $33 million, including $26 million and $7 million, recorded in current assets and other assets, respectively. Debt —The carrying amount of our debt represents the principal amount, net of unamortized discounts, premiums, debt issue costs and fair value adjustments. We measured the estimated fair value of our debt using significant other observable inputs, representative of a Level 2 fair value measurement, including the terms and credit spreads for the instruments. Derivative instruments —The carrying amount of our derivative instruments represents the estimated fair value of such instruments. We measured the estimated fair value of our derivative instruments using significant other observable inputs, representative of a Level 2 fair value measurement, including the terms and credit spreads for the instruments.

Subsequent Event

Subsequent Event	9 Months Ended
	Sep. 30, 2018
Subsequent Events
Subsequent Event	Note 15—Subsequent Event Debt issuance —On October 25, 2018, we issued $750 million aggregate principal amount of 7.25% senior unsecured notes due November 2025 (the “7.25% Senior Notes”), and we received aggregate cash proceeds of $735 million, net of issue costs. We intend to use the net proceeds from this offering to pay a portion of the cash consideration for the Ocean Rig acquisition and for related fees and expenses, or for general corporate purposes. The 7.25% Senior Notes are fully and unconditionally guaranteed by Transocean Ltd. and certain wholly owned subsidiaries of Transocean Inc. Such notes rank equal in right of payment to all of our existing and future unsecured unsubordinated obligations and rank structurally senior to the extent of the value of the assets of the subsidiaries guaranteeing the notes. We may redeem all or a portion of the 7.25% Senior Notes at any time prior to November 1, 2021 at a price equal to 100 percent of the aggregate principal amount plus a make‑whole provision, and on or after November 1, 2021, at specified redemption prices. The indenture that governs the 7.25% Senior Notes contains covenants that, among other things, limit our ability to incur certain liens on our drilling units without equally and ratably securing the notes, engage in certain sale and lease‑back transactions covering any of our drilling units, allow our subsidiaries to incur certain additional debt, and consolidate, merge or enter into a scheme of arrangement qualifying as an amalgamation.

Significant Accounting Polici_2

Significant Accounting Policies (Policies)	9 Months Ended
	Sep. 30, 2018
Significant Accounting Policies
Presentation	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. 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 and nine months ended September 30, 2018, are not necessarily indicative of the results that may be expected for the year ending December 31, 2018, 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, 2017 and 2016, and for each of the three years in the period ended December 31, 2017, included in our annual report on Form 10‑K filed on February 21, 2018.
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, assets held for sale, goodwill, income taxes, contingencies, share‑based compensation and postemployment benefit plans. We base our estimates and assumptions on historical experience and on various other factors we believe are reasonable under the circumstances, the results of which form the basis for making judgments about the carrying amounts of assets and liabilities that are not readily apparent from other sources. Actual results could differ from such estimates.
Fair value measurements	Fair value measurements —We estimate fair value at a price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants in the principal market for the asset or liability. Our valuation techniques require inputs that we categorize using a three‑level hierarchy, from highest to lowest level of observable inputs, as follows: (1) significant observable inputs, including unadjusted quoted prices for identical assets or liabilities in active markets (“Level 1”), (2) significant other observable inputs, including direct or indirect market data for similar assets or liabilities in active markets or identical assets or liabilities in less active markets (“Level 2”) and (3) significant unobservable inputs, including those that require considerable judgment for which there is little or no market data (“Level 3”). When multiple input levels are required for a valuation, we categorize the entire fair value measurement according to the lowest level of input that is significant to the measurement even though we may have also utilized significant inputs that are more readily observable.
Business combination	Business combination —In connection with the Songa acquisition, we applied the acquisition method of accounting. Accordingly, we recorded the acquired assets and assumed liabilities at fair value and recognized goodwill to the extent the consideration transferred exceeded the fair value of the net assets acquired. We estimated the fair values of the acquired assets and assumed liabilities as of the date of the acquisition, and our estimates are subject to adjustment based on our final assessments of the fair values of property and equipment, intangible assets, other assets and liabilities and our evaluation of tax positions and contingencies, which are ongoing. We will complete our final assessments of the fair values of the acquired assets and assumed liabilities and our final evaluations of uncertain tax positions and contingencies within one year of the acquisition date. See Note 4—Business Combinations.
Goodwill	Goodwill —We conduct impairment testing for our goodwill annually as of October 1 and more frequently, on an interim basis, when an event occurs or circumstances change that indicate that the fair value of our reporting unit may have declined below its carrying value. We test goodwill at the reporting unit level, which is defined as an operating segment or one level below an operating segment that constitutes a business for which financial information is available and is regularly reviewed by management. We determined that we have a single reporting unit for this purpose. Before testing goodwill, we consider whether or not to first assess qualitative factors to determine whether the existence of events or circumstances leads to a determination that it is more likely than not that the fair value of a reporting unit is less than its carrying amount. If, as the result of our qualitative assessment, we determine that an impairment test is required, or, alternatively, if we elect to forgo the qualitative assessment, we record an impairment to goodwill to the extent the carrying amount of the reporting unit, including goodwill, exceeds the fair value of the reporting unit. In the nine months ended September 30, 2018, as a result of an interim goodwill test, we recognized an aggregate loss of $462 million, which had no tax effect, associated with the impairment of our goodwill. See Note 3—Accounting Standards Updates, Note 4—Business Combinations and Note 7—Goodwill.
Contract intangible assets	Contract intangible assets —In connection with the Songa acquisition, we recognized drilling contract intangible assets related to the acquired drilling contracts for future contract drilling services. The drilling contract intangible assets represent the amount by which the fixed dayrates of the acquired contracts were above the market dayrates that were available or expected to be available during the term of the contract for similar contracts, measured as of the acquisition date. We recognize the amortization on a straight‑line basis over the firm contract period as a reduction of contract drilling revenues. At September 30, 2018, the carrying amount of our drilling contract intangible assets was $554 million. See Note 4—Business Combinations.
Derivative instruments	Derivative instruments —We record derivatives on our consolidated balance sheet, measured at fair value. We recognize the gains and losses associated with changes in the fair value of undesignated derivatives in current period earnings. See Note 9—Derivative Instruments.
Capitalized interest	Capitalized interest —We capitalize interest costs for qualifying construction and upgrade projects and only capitalize interest costs during periods in which progress for the construction projects continues to be underway. In the three and nine months ended September 30, 2018, we capitalized interest costs of $8 million and $28 million, respectively, for our construction work in progress. In the three and nine months ended September 30, 2017, we capitalized interest costs of $31 million and $91 million, respectively, for our construction work in progress.
Reclassifications	Reclassifications —We have made certain reclassifications to prior period amounts to conform with the current period’s presentation. In our condensed consolidated balance sheet as of December 31, 2017, we reclassified certain balances receivable from non‑customers, totaling $45 million, from accounts receivable, net, to other current assets. Such reclassifications did not have a material effect on our condensed consolidated statement of financial position, results of operations or cash flows.

Business Combinations (Tables)

Business Combinations (Tables)	9 Months Ended
	Sep. 30, 2018
Business Combinations
Schedule of consideration transferred	Total Consideration transferred Aggregate fair value of shares issued as partial consideration for Songa shares $ 735 Aggregate fair value of Exchangeable Bonds issued as partial consideration for Songa shares 675 Consideration transferred to Songa shareholders 1,410 Aggregate fair value of Exchangeable Bonds issued for settlement of certain Songa indebtedness 351 Total consideration transferred in business combination $ 1,761
Schedule of assets acquired and liabilities assumed	We estimated the fair value of assets acquired, liabilities assumed and noncontrolling interest, measured as of January 30, 2018, as follows (in millions): Total Assets acquired Cash and cash equivalents $ 113 Accounts receivable 115 Other current assets 80 Property and equipment 2,414 Goodwill 462 Contract intangible assets 632 Liabilities assumed Accounts payable and other current liabilities 178 Debt 1,768 Other long-term liabilities 76 Net assets acquired 1,794 Noncontrolling interest in business combination 33 Controlling interest acquired in business combination $ 1,761
Schedule of estimated future recognition of contract intangible revenues	As of September 30, 2018, the estimated future amortization of contract intangible assets was as follows (in millions): Total Twelve months ending September 30, 2019 $ 117 2020 117 2021 117 2022 117 2023 74 Thereafter 12 Total carrying amount of contract intangible assets $ 554
Schedule of unaudited pro forma combined operating results	Pro forma combined operating results, assuming the acquisition was completed as of January 1, 2017, were as follows (in millions, except per share data): Three months ended Nine months ended September 30, September 30, 2018 2017 2018 2017 Contract drilling revenues $ 816 $ 954 $ 2,319 $ 2,749 Net loss (409) (1,417) (1,753) (2,977) Per share loss - basic and diluted (0.88) (3.11) (3.79) (6.55)

Revenues (Tables)

Revenues (Tables)	9 Months Ended
	Sep. 30, 2018
Revenues
Schedule of revenue disaggregation	In the three and nine months ended September 30, 2018 and 2017, we recognized revenues as follows (in millions): Three months ended September 30, 2018 Three months ended September 30, 2017 U.S. U.K. Norway Brazil Other Total U.S. U.K. Norway Brazil Other Total Ultra-deepwater floaters $ 396 $ — $ — $ 1 $ 86 $ 483 $ 368 $ — $ — $ 39 $ 116 $ 523 Harsh environment floaters — 37 174 — 54 265 8 62 15 — 33 118 Deepwater floaters — — — 25 11 36 — — — 24 11 35 Midwater floaters — 10 — — 9 19 — 8 — — 96 104 High-specification jackups — — — — 13 13 — — — — 28 28 Total revenues $ 396 $ 47 $ 174 $ 26 $ 173 $ 816 $ 376 $ 70 $ 15 $ 63 $ 284 $ 808 Nine months ended September 30, 2018 Nine months ended September 30, 2017 U.S. U.K. Norway Brazil Other Total U.S. U.K. Norway Brazil Other Total Ultra-deepwater floaters $ 1,162 $ — $ — $ 1 $ 168 $ 1,331 $ 1,167 $ — $ — $ 198 $ 244 $ 1,609 Harsh environment floaters — 88 467 — 166 721 8 197 54 — 89 348 Deepwater floaters — — — 74 32 106 — — — 73 33 106 Midwater floaters — 30 — — 27 57 — 22 — — 114 136 High-specification jackups — — — — 55 55 — 33 — — 112 145 Total revenues $ 1,162 $ 118 $ 467 $ 75 $ 448 $ 2,270 $ 1,175 $ 252 $ 54 $ 271 $ 592 $ 2,344
Schedule of contract balances and changes	Contract liabilities for our contracts with customers were as follows (in millions): September 30, January 1, 2018 2018 Deferred contract revenues, recorded in other current liabilities $ 90 $ 203 Deferred contract revenues, recorded in other long-term liabilities 408 422 Total contract liabilities $ 498 $ 625 Significant changes in contract liabilities were as follows (in millions): Nine months ended September 30, 2018 Total contract liabilities, beginning of period 625 Decrease due to recognition of revenues for goods and services (192) Increase due to goods and services transferred over time 65 Total contract liabilities, end of period $ 498

Drilling Fleet (Tables)

Drilling Fleet (Tables)	9 Months Ended
	Sep. 30, 2018
Drilling Fleet
Changes in our construction work in progress, including capital expenditures and capitalized interest	For the nine months ended September 30, 2018 and 2017, the changes in our construction work in progress, including capital expenditures and other capital additions, were as follows (in millions): Nine months ended September 30, 2018 2017 Construction work in progress, beginning of period $ 1,392 $ 2,171 Capital expenditures Newbuild construction program 64 299 Other equipment and construction projects 76 87 Total capital expenditures 140 386 Changes in accrued capital additions (6) (22) Construction work in progress acquired in business combination 26 — Construction work in progress sold — (289) Property and equipment placed into service Newbuild construction program (903) — Other property and equipment (61) (66) Construction work in progress, end of period $ 588 $ 2,180

Debt (Tables)

Debt (Tables)	9 Months Ended
	Sep. 30, 2018
Debt
Debt, net of unamortized discounts, premiums and fair value adjustments	The aggregate principal amounts and aggregate carrying amounts, net of debt‑related balances, including unamortized discounts, premiums, issue costs and fair value adjustments of our debt, were as follows (in millions): Principal amount Carrying amount September 30, December 31, September 30, December 31, 2018 2017 2018 2017 Eksportfinans Loan due January 2018 $ — $ 26 $ — $ 26 6.50% Senior Notes due November 2020 286 286 288 288 6.375% Senior Notes due December 2021 328 328 327 327 5.52% Senior Secured Notes due May 2022 303 362 299 356 3.80% Senior Notes due October 2022 411 506 408 502 0.50% Exchangeable Bonds due January 2023 863 — 862 — 9.00% Senior Notes due July 2023 1,250 1,250 1,220 1,216 5.875% Senior Secured Notes due January 2024 750 — 734 — 7.75% Senior Secured Notes due October 2024 510 540 498 526 6.25% Senior Secured Notes due December 2024 531 562 520 549 6.125% Senior Secured Notes due August 2025 600 — 587 — 7.50% Senior Notes due January 2026 750 750 742 742 7.45% Notes due April 2027 88 88 86 86 8.00% Debentures due April 2027 57 57 57 57 7.00% Notes due June 2028 300 300 307 307 Capital lease contract due August 2029 519 541 519 541 7.50% Notes due April 2031 588 588 585 585 6.80% Senior Notes due March 2038 1,000 1,000 991 991 7.35% Senior Notes due December 2041 300 300 297 297 Total debt 9,434 7,484 9,327 7,396 Less debt due within one year Eksportfinans Loan due January 2018 — 26 — 26 5.52% Senior Secured Notes due May 2022 83 79 81 77 5.875% Senior Secured Notes due January 2024 83 — 79 — 7.75% Senior Secured Notes due October 2024 60 60 58 57 6.25% Senior Secured Notes due December 2024 62 62 60 60 6.125% Senior Secured Notes due August 2025 66 — 63 — Capital lease contract due August 2029 31 30 31 30 Total debt due within one year 385 257 372 250 Total long-term debt $ 9,049 $ 7,227 $ 8,955 $ 7,146
Scheduled maturities of debt	Total Twelve months ending September 30, 2019 $ 385 2020 392 2021 685 2022 681 2023 2,838 Thereafter 4,453 Total principal amount of debt 9,434 Total debt-related balances, net (107) Total carrying amount of debt $ 9,327
Schedule of debt repurchases and redemptions	During the nine months ended September 30, 2018 and 2017, we repurchased in the open market debt securities with aggregate principal amounts as follows (in millions): Nine months ended September 30, 2018 2017 2.50% Senior Notes due October 2017 $ — $ 62 6.00% Senior Notes due March 2018 — 35 7.375% Senior Notes due April 2018 — 1 6.50% Senior Notes due November 2020 — 9 6.375% Senior Notes due December 2021 — 7 3.80% Senior Notes due October 2022 95 33 Aggregate principal amount retired $ 95 $ 147 Aggregate cash payment $ 95 $ 147
Schedule of tender offers	We received valid tenders from holders of aggregate principal amounts of the 2017 Tendered Notes as follows (in million): Nine months ended September 30, 2017 2.50% Senior Notes due October 2017 $ 271 6.00% Senior Notes due March 2018 400 7.375% Senior Notes due April 2018 128 6.50% Senior Notes due November 2020 207 6.375% Senior Notes due December 2021 213 Aggregate principal amount retired $ 1,219 Aggregate cash payment $ 1,269

Loss Per Share (Tables)

Loss Per Share (Tables)	9 Months Ended
	Sep. 30, 2018
Loss Per Share
Loss Per Share	The numerator and denominator used for the computation of basic and diluted per share loss were as follows (in millions, except per share data): Three months ended September 30, Nine months ended September 30, 2018 2017 2018 2017 Basic Diluted Basic Diluted Basic Diluted Basic Diluted Numerator for loss per share Net loss attributable to controlling interest $ (409) $ (409) $ (1,417) $ (1,417) $ (1,754) $ (1,754) $ (3,016) $ (3,016) Undistributed earnings allocable to participating securities — — — — — — — — Net loss available to shareholders $ (409) $ (409) $ (1,417) $ (1,417) $ (1,754) $ (1,754) $ (3,016) $ (3,016) Denominator for loss per share Weighted-average shares outstanding 463 463 391 391 454 454 391 391 Effect of share-based awards and other equity instruments — — — — — — — — Weighted-average shares for per share calculation 463 463 391 391 454 454 391 391 Per share loss $ (0.88) $ (0.88) $ (3.62) $ (3.62) $ (3.86) $ (3.86) $ (7.72) $ (7.72)

Financial Instruments (Tables)

Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2018
Financial Instruments
Carrying amounts and fair values of the financial instruments	September 30, 2018 December 31, 2017 Carrying Fair Carrying Fair amount value amount value Cash and cash equivalents $ 2,307 $ 2,307 $ 2,519 $ 2,519 Short-term investments — — 450 450 Restricted cash and cash equivalents 568 568 456 456 Restricted investments 7 7 33 33 Long-term debt, including current maturities 9,327 9,949 7,396 7,538 Derivative instruments, liabilities 2 2 — —

Business (Details)

Business (Details)	9 Months Ended
	Sep. 30, 2018item
Number of mobile offshore drilling units	41
Ultra-deepwater floaters
Number of mobile offshore drilling units	23
Number of mobile offshore drilling units under construction	2
Harsh environment floaters
Number of mobile offshore drilling units	12
Number of mobile offshore drilling units under construction	1
Deepwater floaters
Number of mobile offshore drilling units	2
Midwater floaters
Number of mobile offshore drilling units	4
High specification jackups | Assets sold, not discontinued operations
Number of high specification jackups operated through contract completion or novation	1

Business (Merger and business c

Business (Merger and business combination) (Details) $ / shares in Units, shares in Millions, $ in Millions	Sep. 04, 2018$ / sharesshares	Mar. 28, 2018USD ($)shares	Jan. 30, 2018item$ / sharesshares	Sep. 30, 2018USD ($)item	Dec. 31, 2017USD ($)
Business Combination
Number of mobile offshore drilling units				41
Aggregate principal amount outstanding | $				$ 9,434	$ 7,484
0.50% Exchangeable Bonds due January 2023
Business Combination
Aggregate principal amount outstanding | $		$ 863		$ 863
Debt instrument interest rate stated percentage				0.50%
Ocean Rig
Business Combination
Number of mobile offshore drilling units				11
Ultra-deepwater floaters
Business Combination
Number of mobile offshore drilling units				23
Ultra-deepwater floaters | Ocean Rig
Business Combination
Number of mobile offshore drilling units				9
Harsh environment floaters
Business Combination
Number of mobile offshore drilling units				12
Harsh environment floaters | Ocean Rig
Business Combination
Number of mobile offshore drilling units				2
Midwater floaters
Business Combination
Number of mobile offshore drilling units				4
Ocean Rig
Business Combination
Ratio of shares to be issued for consideration	1.6128
Business combination consideration (per share) | $ / shares	$ 12.75
Newly issued shares (in shares) | shares	147.7
Songa
Business Combination
Ownership interest (as a percent)			97.70%
Business combination consideration (per share) | $ / shares			$ 10.99
Number of mobile offshore drilling units			7
Newly issued shares (in shares) | shares		68	66.9
Songa | 0.50% Exchangeable Bonds due January 2023
Business Combination
Aggregate principal amount outstanding | $		$ 863
Debt instrument interest rate stated percentage		0.50%
Songa | Harsh environment floaters
Business Combination
Number of mobile offshore drilling units			5
Songa | Midwater floaters
Business Combination
Number of mobile offshore drilling units			2

Business (Investment in unconso

Business (Investment in unconsolidated affiliates) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)
Investments
Investment in unconsolidated affiliate	$ 107
Cost method investment	16
Transocean Norge
Investments
Equity method investment	$ 91
Ownership percentage	33.00%
Total purchase price for investment	$ 500
Transocean Norge | January 2019 payment
Investments
Equity method investment	$ 50
Transocean Norge | January 2020 payment
Investments
Equity method investment	$ 33

Significant Accounting Polici_3

Significant Accounting Policies (Condensed) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Loss on impairment of goodwill			$ 462
Loss on impairment of goodwill, tax effect			0
Contract intangible assets	$ 554		554
Capitalized interest costs on construction work in progress	8	$ 31	28	$ 91
Accounts receivable, net	627		627		$ 596
Other current assets	$ 169		$ 169		157
Reclassifications
Accounts receivable, net					(45)
Other current assets					$ 45

Accounting Standards Updates (D

Accounting Standards Updates (Details) - ASU-Leases - Forecast Adjustment $ in Millions	Sep. 30, 2018USD ($)
Minimum
Recently issued accounting standards
Aggregate lease liability	$ 65
Right-to-use asset	65
Lease liability that has not yet commenced	60
Maximum
Recently issued accounting standards
Aggregate lease liability	75
Right-to-use asset	75
Lease liability that has not yet commenced	$ 65

Business Combinations (Details)

Business Combinations (Details) $ / shares in Units, shares in Millions, $ in Millions	Sep. 04, 2018USD ($)$ / sharesshares	Mar. 28, 2018USD ($)shares	Jan. 30, 2018USD ($)item$ / sharesshares	Jan. 16, 2018shares	Sep. 30, 2018USD ($)item	Sep. 30, 2017USD ($)
Business Combination
Number of mobile offshore drilling units | item					41
Aggregate consideration
Acquisition of noncontrolling interest in compulsory acquisition					$ 31
Ultra-deepwater floaters
Business Combination
Number of mobile offshore drilling units | item					23
Number of mobile offshore drilling units under construction | item					2
Harsh environment floaters
Business Combination
Number of mobile offshore drilling units | item					12
Number of mobile offshore drilling units under construction | item					1
Ocean Rig
Business Combination
Number of mobile offshore drilling units | item					11
Ocean Rig | Ultra-deepwater floaters
Business Combination
Number of mobile offshore drilling units | item					9
Number of mobile offshore drilling units under construction | item					2
Ocean Rig | Harsh environment floaters
Business Combination
Number of mobile offshore drilling units | item					2
Ocean Rig
Business Combination
Ratio of shares to be issued for consideration	1.6128
Business combination consideration (per share) | $ / shares	$ 12.75
Newly issued shares (in shares) | shares	147.7
Maximum cash consideration	$ 1,170
Songa
Business Combination
Business combination consideration (per share) | $ / shares			$ 10.99
Newly issued shares (in shares) | shares		68	66.9
Number of mobile offshore drilling units | item			7
Ownership interest (as a percent)			97.70%
Acquisition costs					$ 7	$ 3
Aggregate consideration
Aggregate fair value of shares issued as partial consideration for Songa shares			$ 735
Consideration transferred to Songa shareholders			1,410
Total consideration			1,761
Issuance of shares in acquisition transactions (in shares) | shares		1.1
Cash payment to acquire noncontrolling interest		$ 8
Songa | Maximum
Business Combination
Newly issued shares (in shares) | shares				68.6
Songa | 0.50% Exchangeable Bonds due January 2023
Business Combination
Convertible debt		9	854
Aggregate consideration
Acquisition of noncontrolling interest in compulsory acquisition		$ 30
Songa | 0.50% Exchangeable Bonds, acquire Songa shares
Business Combination
Convertible debt			562
Aggregate consideration
Aggregate fair value of Exchangeable Bonds issued			675
Songa | 0.50% Exchangeable Bonds, settle Songa debt
Business Combination
Convertible debt			292
Aggregate consideration
Aggregate fair value of Exchangeable Bonds issued			$ 351
Songa | Harsh environment floaters
Business Combination
Number of mobile offshore drilling units | item			5
Songa | High specification harsh environment floaters
Business Combination
Number of mobile offshore drilling units | item			4

Business Combinations (Allocati

Business Combinations (Allocation) (Details) - Songa $ in Millions	Jan. 30, 2018USD ($)
Acquisition price allocation
Cash and cash equivalents	$ 113
Accounts receivable	115
Other current assets	80
Property and equipment	2,414
Goodwill	462
Contract intangible assets	632
Accounts payable and other current liabilities	178
Debt	1,768
Other long-term liabilities	76
Net assets acquired	1,794
Noncontrolling interest in business combination	33
Controlling interest acquired in business combination	$ 1,761

Business Combinations (Intangib

Business Combinations (Intangibles) (Details) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2018USD ($)	Sep. 30, 2018USD ($)
Intangibles
Recognition of contract intangible revenues	$ 29	$ 78
Total carrying amount of contract intangible assets	554	554
Contract intangible revenues
Intangibles
2,019	117	117
2,020	117	117
2,021	117	117
2,022	117	117
2,023	74	74
Thereafter	12	12
Total carrying amount of contract intangible assets	554	554
Songa
Intangibles
Total carrying amount of contract intangible assets	$ 554	$ 554

Business Combinations (Proforma

Business Combinations (Proforma) (Details) - Songa - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Pro forma information
Revenue since acquisition	$ 137		$ 356
Net income since acquisition	16		36
Contract drilling revenues	816	$ 954	2,319	$ 2,749
Net loss	$ (409)	$ (1,417)	$ (1,753)	$ (2,977)
Per share loss - basic and diluted (in dollars per share)	$ (0.88)	$ (3.11)	$ (3.79)	$ (6.55)

Revenues (Disaggregation) (Deta

Revenues (Disaggregation) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Revenue
Performance obligations satisfied in previous periods	$ 54		$ 147
Recognized pre-operating costs	14	$ 11	36	$ 35
Unrecognized pre-operating costs	10		10		$ 18
Contract drilling revenues	816	808	2,270	2,344
Before adoption of Topic 606
Revenue
Contract drilling revenues		808		2,344
Ultra-deepwater floaters
Revenue
Contract drilling revenues	483		1,331
Ultra-deepwater floaters | Before adoption of Topic 606
Revenue
Contract drilling revenues		523		1,609
Harsh environment floaters
Revenue
Contract drilling revenues	265		721
Harsh environment floaters | Before adoption of Topic 606
Revenue
Contract drilling revenues		118		348
Deepwater floaters
Revenue
Contract drilling revenues	36		106
Deepwater floaters | Before adoption of Topic 606
Revenue
Contract drilling revenues		35		106
Midwater floaters
Revenue
Contract drilling revenues	19		57
Midwater floaters | Before adoption of Topic 606
Revenue
Contract drilling revenues		104		136
High specification jackups
Revenue
Contract drilling revenues	13		55
High specification jackups | Before adoption of Topic 606
Revenue
Contract drilling revenues		28		145
U.S.
Revenue
Contract drilling revenues	396		1,162
U.S. | Before adoption of Topic 606
Revenue
Contract drilling revenues		376		1,175
U.S. | Ultra-deepwater floaters
Revenue
Contract drilling revenues	396		1,162
U.S. | Ultra-deepwater floaters | Before adoption of Topic 606
Revenue
Contract drilling revenues		368		1,167
U.S. | Harsh environment floaters | Before adoption of Topic 606
Revenue
Contract drilling revenues		8		8
U.K.
Revenue
Contract drilling revenues	47		118
U.K. | Before adoption of Topic 606
Revenue
Contract drilling revenues		70		252
U.K. | Harsh environment floaters
Revenue
Contract drilling revenues	37		88
U.K. | Harsh environment floaters | Before adoption of Topic 606
Revenue
Contract drilling revenues		62		197
U.K. | Midwater floaters
Revenue
Contract drilling revenues	10		30
U.K. | Midwater floaters | Before adoption of Topic 606
Revenue
Contract drilling revenues		8		22
U.K. | High specification jackups | Before adoption of Topic 606
Revenue
Contract drilling revenues				33
Norway
Revenue
Contract drilling revenues	174		467
Norway | Before adoption of Topic 606
Revenue
Contract drilling revenues		15		54
Norway | Harsh environment floaters
Revenue
Contract drilling revenues	174		467
Norway | Harsh environment floaters | Before adoption of Topic 606
Revenue
Contract drilling revenues		15		54
Brazil
Revenue
Contract drilling revenues	26		75
Brazil | Before adoption of Topic 606
Revenue
Contract drilling revenues		63		271
Brazil | Ultra-deepwater floaters
Revenue
Contract drilling revenues	1		1
Brazil | Ultra-deepwater floaters | Before adoption of Topic 606
Revenue
Contract drilling revenues		39		198
Brazil | Deepwater floaters
Revenue
Contract drilling revenues	25		74
Brazil | Deepwater floaters | Before adoption of Topic 606
Revenue
Contract drilling revenues		24		73
Other
Revenue
Contract drilling revenues	173		448
Other | Before adoption of Topic 606
Revenue
Contract drilling revenues		284		592
Other | Ultra-deepwater floaters
Revenue
Contract drilling revenues	86		168
Other | Ultra-deepwater floaters | Before adoption of Topic 606
Revenue
Contract drilling revenues		116		244
Other | Harsh environment floaters
Revenue
Contract drilling revenues	54		166
Other | Harsh environment floaters | Before adoption of Topic 606
Revenue
Contract drilling revenues		33		89
Other | Deepwater floaters
Revenue
Contract drilling revenues	11		32
Other | Deepwater floaters | Before adoption of Topic 606
Revenue
Contract drilling revenues		11		33
Other | Midwater floaters
Revenue
Contract drilling revenues	9		27
Other | Midwater floaters | Before adoption of Topic 606
Revenue
Contract drilling revenues		96		114
Other | High specification jackups
Revenue
Contract drilling revenues	$ 13		$ 55
Other | High specification jackups | Before adoption of Topic 606
Revenue
Contract drilling revenues		$ 28		$ 112

Revenues (Contract liabilities)

Revenues (Contract liabilities) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Contract balances
Deferred contract revenues, recorded in other current liabilities	$ 90	$ 203
Deferred contract revenues, recorded in other long-term liabilities	408	422
Total contract liabilities	$ 498	$ 625	$ 625

Revenues (Changes) (Details)

Revenues (Changes) (Details) $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)
Significant changes to contract liabilities
Total contract liabilities, at beginning of period	$ 625
Decrease due to recognition of revenues for goods and services	(192)
Increase due to goods and services transferred over time	65
Total contract liabilities, at end of period	$ 498

Drilling Fleet (Details)

Drilling Fleet (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Changes in construction work in progress, including capital expenditures and other capital additions, such as capitalized interest
Total capital expenditures	$ 140	$ 386
Construction in Progress
Changes in construction work in progress, including capital expenditures and other capital additions, such as capitalized interest
Construction work in progress, at beginning of period	1,392	2,171
Total capital expenditures	140	386
Changes in accrued capital additions	(6)	(22)
Construction work in progress acquired in business combination	26
Construction work in progress sold		(289)
Construction work in progress, at end of period	588	2,180
New builds
Changes in construction work in progress, including capital expenditures and other capital additions, such as capitalized interest
Total capital expenditures	64	299
Property and equipment placed into service	(903)
Other property and equipment
Changes in construction work in progress, including capital expenditures and other capital additions, such as capitalized interest
Total capital expenditures	76	87
Property and equipment placed into service	$ (61)	$ (66)

Drilling Fleet (Impairment held

Drilling Fleet (Impairment held and used) (Details) - Midwater floaters $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2017USD ($)$ / shares
Impairment of assets held and used
Impairment of in use assets	$ 94
Loss associated with in use asset impairment, net of tax	$ 95
Loss associated with impairment, net of tax (per share) | $ / shares	$ 0.25

Drilling Fleet (Impairment he_2

Drilling Fleet (Impairment held for sale) (Details) - Rig sales - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Assets held for sale
Aggregate loss on impairment of assets held for sale	$ 433	$ 1,400	$ 981	$ 1,400
Aggregate loss on impairment of assets held for sale, tax effect			$ 0	$ 0
Loss associated with impairment, net of tax (per share)	$ 0.93	$ 3.54	$ 2.15	$ 3.60

Drilling Fleet (Disposal) (Deta

Drilling Fleet (Disposal) (Details) $ / shares in Units, $ in Millions	May 31, 2017item	Sep. 30, 2018USD ($)item	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)item$ / shares	Sep. 30, 2017USD ($)$ / shares	Dec. 31, 2017USD ($)
Dispositions
Number of mobile offshore drilling units | item		41		41
Net cash proceeds from sale of assets				$ 37	$ 330
Gain (loss) on the sale of assets		$ (6)	$ (9)		(1,602)
Assets held for sale, included in other current assets		26		$ 26		$ 22
Assets sold, not discontinued operations | High specification jackups
Dispositions
Number of mobile offshore drilling units | item	10
Number of mobile offshore drilling units under construction | item	5
Net cash proceeds from sale of assets					319
Gain (loss) on the sale of assets					$ (1,600)
Gain (loss) on the sale of assets per diluted share | $ / shares					$ (4.08)
Gain (loss) on disposal of assets, tax effect					$ 0
Number of high specification jackups operated through contract completion or novation | item	3			1
Disposal group operating income		$ 10	19	$ 42	46
Assets sold, not discontinued operations | Rig sales
Dispositions
Net cash proceeds from sale of assets				31
Gain (loss) on the sale of assets				$ 6
Gain (loss) on the sale of assets per diluted share | $ / shares				$ 0.02
Gain (loss) on disposal of assets, tax effect				$ 0
Assets sold, not discontinued operations | Other property and equipment
Dispositions
Net cash proceeds from sale of assets			1	6	8
Gain (loss) on the sale of assets			$ (9)	$ (6)	(8)
Assets sold, not discontinued operations | Midwater floaters
Dispositions
Net cash proceeds from sale of assets					3
Gain (loss) on the sale of assets					$ 2

Goodwill (Details)

Goodwill (Details) $ / shares in Units, $ in Millions	9 Months Ended
	Sep. 30, 2018USD ($)$ / shares	Jun. 30, 2018item
Goodwill
Number of impaired ultra-deepwater floaters | item		3
Loss on impairment of goodwill	$ 462
Loss on impairment of goodwill per diluted share from continuing operations | $ / shares	$ 1.02
Loss on impairment of goodwill, tax effect	$ 0

Debt (Details)

Debt (Details) $ / shares in Units, kr in Millions, $ in Millions	Aug. 20, 2018USD ($)	Jul. 20, 2018USD ($)	Jul. 13, 2018USD ($)	Mar. 14, 2018NOK (kr)	Mar. 14, 2018USD ($)	Feb. 02, 2018USD ($)	Jan. 30, 2018NOK (kr)	May 05, 2017USD ($)	Jun. 30, 2018USD ($)	Jun. 30, 2014USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2017USD ($)	Mar. 28, 2018USD ($)	Jan. 30, 2018USD ($)$ / shares	Dec. 31, 2017USD ($)	Jul. 11, 2017USD ($)
Principal amount
Total principal amount of debt											$ 9,434		$ 9,434				$ 7,484
Debt due within one year											385		385				257
Long-term debt											9,049		9,049				7,227
Carrying amount
Total debt											9,327		9,327				7,396
Debt due within one year											372		372				250
Long-term debt											8,955		8,955				7,146
Loss on retirement of debt											(1)	$ (1)	(3)	$ (49)
Equity component of convertible debt instruments													172
Proceeds from issuance of debt													1,319	403
Restricted cash and cash equivalents											568		568				456
Eksportfinans Loans due January 2018
Principal amount
Total principal amount of debt																	26
Debt due within one year																	26
Carrying amount
Total debt																	26
Debt due within one year																	26
6.50% Senior Notes due November 2020
Principal amount
Total principal amount of debt											286		286				286
Carrying amount
Total debt											$ 288		$ 288				288
Debt instrument interest rate stated percentage											6.50%		6.50%
Aggregate debt repurchase												207		207
Aggregate principal amount repaid														9
6.375% Senior Notes due December 2021
Principal amount
Total principal amount of debt											$ 328		$ 328				328
Carrying amount
Total debt											$ 327		$ 327				327
Debt instrument interest rate stated percentage											6.375%		6.375%
Interest rate, as adjusted (as a percent)													8.375%
Aggregate debt repurchase												213		213
Aggregate principal amount repaid														7
5.52% Senior Notes due May 2022
Principal amount
Total principal amount of debt											$ 303		$ 303				362
Debt due within one year											83		83				79
Carrying amount
Total debt											299		299				356
Debt due within one year											$ 81		$ 81				77
Debt instrument interest rate stated percentage								5.52%			5.52%		5.52%
Debt instrument face value								$ 410
Proceeds from issuance of debt								$ 403
3.80% Senior Notes due October 2022
Principal amount
Total principal amount of debt											$ 411		$ 411				506
Carrying amount
Total debt											$ 408		$ 408				502
Debt instrument interest rate stated percentage											3.80%		3.80%
Interest rate, as adjusted (as a percent)													5.80%
Aggregate principal amount repaid													$ 95	33
0.50% Exchangeable Bonds due January 2023
Principal amount
Total principal amount of debt											$ 863		863		$ 863
Carrying amount
Total debt											$ 862		$ 862
Debt instrument interest rate stated percentage											0.50%		0.50%
Debt conversion ratio							0.09729756
Debt conversion (in dollars per share) | $ / shares																$ 10.28
Fair value of debt																$ 1,040
Equity component of convertible debt instruments													$ 172
9.00% Senior Notes due July 2023
Principal amount
Total principal amount of debt											$ 1,250		1,250				1,250
Carrying amount
Total debt											$ 1,220		$ 1,220				1,216
Debt instrument interest rate stated percentage									9.00%		9.00%		9.00%
5.875% Senior Secured Notes due January 2024
Principal amount
Total principal amount of debt											$ 750		$ 750
Debt due within one year											83		83
Carrying amount
Total debt											734		734
Debt due within one year											$ 79		$ 79
Debt instrument interest rate stated percentage			5.875%								5.875%		5.875%
Debt instrument face value			$ 750
Proceeds from issuance of debt			733
Restricted cash and cash equivalents			$ 63
Maximum Collateral Ratio			6
7.75% Senior Secured Notes due October 2024
Principal amount
Total principal amount of debt											$ 510		$ 510				540
Debt due within one year											60		60				60
Carrying amount
Total debt											498		498				526
Debt due within one year											$ 58		$ 58				57
Debt instrument interest rate stated percentage											7.75%		7.75%
6.25% Senior Notes due December 2024
Principal amount
Total principal amount of debt											$ 531		$ 531				562
Debt due within one year											62		62				62
Carrying amount
Total debt											520		520				549
Debt due within one year											$ 60		$ 60				60
Debt instrument interest rate stated percentage											6.25%		6.25%
6.125% Senior Secured Notes due August 2025
Principal amount
Total principal amount of debt											$ 600		$ 600
Debt due within one year											66		66
Carrying amount
Total debt											587		587
Debt due within one year											$ 63		$ 63
Debt instrument interest rate stated percentage		6.125%									6.125%		6.125%
Debt instrument face value		$ 600
Proceeds from issuance of debt		586
Restricted cash and cash equivalents		$ 51
Maximum Collateral Ratio		5.75
7.50% Senior Notes due January 2026
Principal amount
Total principal amount of debt											$ 750		$ 750				750
Carrying amount
Total debt											$ 742		$ 742				742
Debt instrument interest rate stated percentage											7.50%		7.50%
7.45% Notes due April 2027
Principal amount
Total principal amount of debt											$ 88		$ 88				88
Carrying amount
Total debt											$ 86		$ 86				86
Debt instrument interest rate stated percentage											7.45%		7.45%
8.00% Debentures due April 2027
Principal amount
Total principal amount of debt											$ 57		$ 57				57
Carrying amount
Total debt											$ 57		$ 57				57
Debt instrument interest rate stated percentage											8.00%		8.00%
7.00% Notes due June 2028
Principal amount
Total principal amount of debt											$ 300		$ 300				300
Carrying amount
Total debt											$ 307		$ 307				307
Debt instrument interest rate stated percentage											7.00%		7.00%
Capital lease contract due August 2029
Principal amount
Total principal amount of debt											$ 519		$ 519				541
Debt due within one year											31		31				30
Carrying amount
Total debt											519		519				541
Debt due within one year											31		31				30
7.50% Notes due April 2031
Principal amount
Total principal amount of debt											588		588				588
Carrying amount
Total debt											$ 585		$ 585				585
Debt instrument interest rate stated percentage											7.50%		7.50%
6.80% Senior Notes due March 2038
Principal amount
Total principal amount of debt											$ 1,000		$ 1,000				1,000
Carrying amount
Total debt											$ 991		$ 991				991
Debt instrument interest rate stated percentage											6.80%		6.80%
7.35% Senior Notes due December 2041
Principal amount
Total principal amount of debt											$ 300		$ 300				300
Carrying amount
Total debt											$ 297		$ 297				$ 297
Debt instrument interest rate stated percentage											7.35%		7.35%
Interest rate, as adjusted (as a percent)													9.35%
Five-Year Revolving Credit Facility
Carrying amount
Borrowing capacity, maximum									$ 1,000
Aggregate minimum principal amount impacting maturity									300
Minimum liquidity									$ 500
Consolidated indebtedness to total tangible capitalization ratio									0.60
Commitment fee percentage at period end													0.50%
Credit facility amount outstanding											$ 0		$ 0
Letters of credit issued and outstanding											24		24
Credit facility available borrowing capacity											1,000		$ 1,000
Five-Year Revolving Credit Facility | Adjusted LIBOR
Carrying amount
Spread on variable rate basis (as a percent)													2.75%
Percentage reduction to the calculated variable rate									1.00%
Five-Year Revolving Credit Facility | Minimum
Carrying amount
Commitment fee percentage at period end									0.375%
Five-Year Revolving Credit Facility | Minimum | Adjusted LIBOR
Carrying amount
Spread on variable rate basis (as a percent)									2.625%
Five-Year Revolving Credit Facility | Maximum
Carrying amount
Commitment fee percentage at period end									1.00%
Five-Year Revolving Credit Facility | Maximum | Adjusted LIBOR
Carrying amount
Spread on variable rate basis (as a percent)									3.25%
Former Credit Facility
Carrying amount
Borrowing capacity, maximum										$ 3,000
Credit facility term										5 years
Loss on retirement of debt									$ (1)
Bond Loans
Carrying amount
Total debt							kr 337									$ 44
Aggregate cash payment made for debt redemption				kr 345	$ 44
Secured Borrowing Facility
Carrying amount
Aggregate cash payment made for debt redemption						$ 23
2.5% Senior Notes due October 2017
Carrying amount
Aggregate debt repurchase												271		271
Aggregate principal amount repaid														62
6.00% Senior Notes due March 2018
Carrying amount
Aggregate debt repurchase												400		400
Aggregate principal amount repaid														35
7.375% Senior Notes due April 2018
Carrying amount
Aggregate debt repurchase												128		128
Aggregate principal amount repaid														1
2018 Senior Secured Notes
Carrying amount
Redemption price of debt instrument (as a percent)			100.00%
Percentage of principal amount that the holder of the note may require the entity to repurchase upon the occurrence of certain events			100
Senior Secured Term Loans
Carrying amount
Loss on retirement of debt											1
Aggregate cash payment made for debt redemption											1,400
Junior Secured Bonds
Carrying amount
Aggregate cash payment made for debt redemption	$ 171
Debt Redeemed
Carrying amount
Loss on retirement of debt														(1)
Aggregate cash payment made for debt redemption													$ 95	147
Aggregate principal amount repaid													95	147
Debt Redeemed | Maximum
Carrying amount
Loss on retirement of debt											$ (1)		$ (1)
Tendered Notes
Carrying amount
Loss on retirement of debt												(1)		(48)
Aggregate cash payment made for debt redemption														1,269
Aggregate debt repurchase												$ 1,219		$ 1,219
Tender Offer Principal Amount																		$ 1,500

Debt (Maturities) (Details)

Debt (Maturities) (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Scheduled maturities of debt
2,019	$ 385
2,020	392
2,021	685
2,022	681
2,023	2,838
Thereafter	4,453
Total principal amount of debt	9,434	$ 7,484
Total debt-related balances, net	(107)
Total carrying amount of debt	$ 9,327

Derivative Instruments (Details

Derivative Instruments (Details) - Undesignated derivative instruments kr in Millions, $ in Millions	1 Months Ended		3 Months Ended	9 Months Ended
	Jul. 31, 2018USD ($)	Feb. 28, 2018USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2018USD ($)	Sep. 30, 2018NOK (kr)	Sep. 30, 2018USD ($)	Jan. 30, 2018USD ($)
Forward exchange contracts
Derivatives
Exchange rate (as a percent)					7.96	7.96
Fair value adjustments to derivatives			$ (3)	$ (3)
Derivative instruments, liabilities						$ 2
Derivative instruments, assets							$ 4
Forward exchange contracts | Songa
Derivatives
Fair value adjustments to derivatives				(1)
Forward exchange contracts | Pay
Derivatives
Aggregate notional amount						$ 113
Forward exchange contracts | Receive
Derivatives
Aggregate notional amount | kr					kr 900
Interest rate swaps
Derivatives
Fair value adjustments to derivatives			$ (1)	4
Derivative instruments, assets							14
Cash proceeds from termination of derivatives	$ 18
Currency swaps
Derivatives
Derivative instruments, liabilities							$ 81
Loss associated with termination				$ (11)
Cash payment for termination of derivatives		$ 92

Income Taxes (Provision and Ref

Income Taxes (Provision and Reform) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Sep. 30, 2017
Income Taxes
Annual effective tax rate excluding discrete items (as a percent)		(15.60%)	64.20%
Various discrete tax items		$ (91)	$ 57
Annual effective tax rate (as a percent)		(7.20%)	(3.60%)
Valuation allowance change during period	$ 91
Estimated transition taxes		$ 104
Deferred tax assets change due to 2017 Tax Act		$ (17)

Income Taxes (TaxReturns) (Deta

Income Taxes (TaxReturns) (Details) - 9 months ended Sep. 30, 2018 R$ in Millions, $ in Millions	BRL (R$)jurisdiction	USD ($)jurisdiction
Income Tax Examination
Number of jurisdictions with extensions beyond statute of limitations	2	2
Maximum number of years agreed to extensions beyond the statute of limitations	20 years	20 years
Net adjustments of additional taxes, including interest and penalties	R$ 946	$ 234
Minimum
Income Tax Examination
Range of tax returns are subject to examination	3 years	3 years
Maximum
Income Tax Examination
Range of tax returns are subject to examination	6 years	6 years

Loss Per Share (Details)

Loss Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Numerator for loss per share, basic
Net loss attributable to controlling interest	$ (409)	$ (1,417)	$ (1,754)	$ (3,016)
Net loss available to shareholders	$ (409)	$ (1,417)	$ (1,754)	$ (3,016)
Denominator for loss per share, basic
Weighted-average shares outstanding	463	391	454	391
Weighted-average shares for per share calculation, basic	463	391	454	391
Per share loss, basic (in dollars per share)	$ (0.88)	$ (3.62)	$ (3.86)	$ (7.72)
Numerator for loss per share, diluted
Net loss attributable to controlling interest	$ (409)	$ (1,417)	$ (1,754)	$ (3,016)
Net loss available to shareholders	$ (409)	$ (1,417)	$ (1,754)	$ (3,016)
Denominator for loss per share, diluted
Weighted-average shares outstanding	463	391	454	391
Weighted-average shares for per share calculation, diluted	463	391	454	391
Per share loss, diluted (in dollars per share)	$ (0.88)	$ (3.62)	$ (3.86)	$ (7.72)
Share-based awards
Anti-dilutive securities
Securities excluded from earnings per share calculation (in shares)	10.7	5.6	10.7	4.7
0.50% Exchangeable Bonds due January 2023
Anti-dilutive securities
Securities excluded from earnings per share calculation (in shares)	84		74.9

Commitments and Contingencies (

Commitments and Contingencies (Cont) (Details) $ in Millions	May 29, 2015USD ($)item	Jan. 03, 2013USD ($)item	Nov. 30, 2017USD ($)	Jun. 30, 2016USD ($)	Aug. 31, 2015USD ($)	Oct. 31, 2007subsidiary	Sep. 30, 2018USD ($)plaintifflawsuitinstallmentsubsidiary	Sep. 30, 2017USD ($)	Dec. 31, 2017USD ($)	Nov. 28, 2017USD ($)
7.00% Notes due June 2028
Other legal proceedings
Debt instrument interest rate stated percentage							7.00%
Macondo well incident
Contingencies
Amount of fines, recoveries and civil penalties							$ 217		$ 219
PSC Settlement Agreement
Contingencies
Settlement Agreement	$ 212
Number of classes of plaintiffs | item	2
Settlement allocated to Punitive Damage Class (as a percent)	72.80%
Settlement allocated to Assigned Claims Class (as a percent)	27.20%
Cash payment into an escrow account pending approval by MDL Court				$ 25	$ 212
Number of claimants | item	30
Payment of contingency accrual			$ 25
Number of installment | installment							3
Escrow Deposit							$ 214		$ 212
PSC Settlement Agreement Legal Fees
Contingencies
Settlement Agreement	$ 25
Plea Agreement
Contingencies
Number of misdemeanor count of negligently discharging oil | item		1
Amount paid for obligations under the Plea Agreement and Consent Decree including interest		$ 400						$ 60
Other legal proceedings
Number of subsidiaries | item		1
Asbestos litigation
Other legal proceedings
Number of claims | lawsuit							141
Number of subsidiaries | subsidiary							1
Asbestos litigation | LA
Other legal proceedings
Number of claims | plaintiff							9
Nigerian Cabotage Act litigation
Other legal proceedings
Number of subsidiaries | subsidiary						3
Percentage of surcharge on the value of contracts performed in Nigeria pursuant to the Coastal and Inland Shipping (Cabotage) Act 2003 (the Cabotage Act)						2.00%
Global Marine Litigation | 7.00% Notes due June 2028
Other legal proceedings
Debt instrument face value										$ 300
Debt instrument interest rate stated percentage										7.00%
Nigerian customer arbitration
Other legal proceedings
Uncertain collectability of drilling service receivable							$ 80
Hazardous waste disposal sites
Other legal proceedings
Number of subsidiaries | subsidiary							1
Percentage of liability for remediation and related costs							8.00%
Hazardous waste disposal sites | Minimum
Other legal proceedings
Minimum number of subsidiaries likely to be named potentially responsible party by US Environmental Protection Agency for superfund site (in counts) | subsidiary							1

Equity (Details)

Equity (Details) - USD ($) shares in Millions, $ in Millions	Sep. 04, 2018	Jun. 11, 2018	Mar. 28, 2018	Jan. 30, 2018	Jan. 16, 2018	Sep. 30, 2018	Dec. 31, 2017
Variable Interest Entity
Payment to acquire interest						$ 107
Acquisition of redeemable noncontrolling interest						53
Songa
Carrying amounts associated with consolidated variable interest entities
Newly issued shares (in shares)			68	66.9
Songa | Maximum
Carrying amounts associated with consolidated variable interest entities
Newly issued shares (in shares)					68.6
Ocean Rig
Carrying amounts associated with consolidated variable interest entities
Newly issued shares (in shares)	147.7
ADDCL
Variable Interest Entity
Ownership interest in affiliate (as a percent)		65.00%
ADDCL
Variable Interest Entity
Payment to acquire interest		$ 0
Acquisition of redeemable noncontrolling interest						$ 53
Carrying amounts associated with consolidated variable interest entities
Assets							$ 716
Liabilities							$ 7
ADDCL | Angco Cayman Limited
Variable Interest Entity
Ownership interest held by minority interest (as a percent)		35.00%

Financial Instruments (Details)

Financial Instruments (Details) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Financial instruments
Restricted cash and cash equivalents	$ 568	$ 456
Long-term debt, including current maturities	9,327	7,396
Carrying amount
Financial instruments
Cash and cash equivalents	2,307	2,519
Short-term investments		450
Restricted cash and cash equivalents	568	456
Restricted investments	7	33
Long-term debt, including current maturities	9,327	7,396
Derivative instruments, liabilities	2
Fair value
Financial instruments
Cash and cash equivalents	2,307	2,519
Short-term investments		450
Restricted cash and cash equivalents	568	456
Restricted investments	7	33
Long-term debt, including current maturities	9,949	7,538
Derivative instruments, liabilities	2
Other current assets
Financial instruments
Restricted cash and cash equivalents	561	440
Other assets
Financial instruments
Restricted cash and cash equivalents	7	16
Significant other observable inputs
Financial instruments
Restricted investments, noncurrent	$ 7
Significant other observable inputs | Fair value
Financial instruments
Restricted investments		33
Significant other observable inputs | Other current assets | Fair value
Financial instruments
Restricted investments		26
Significant other observable inputs | Other assets | Fair value
Financial instruments
Restricted investments		$ 7

Subsequent Events (Details)

Subsequent Events (Details) - USD ($) $ in Millions	Oct. 25, 2018	Sep. 30, 2018	Sep. 30, 2017
Subsequent events
Proceeds from issuance of debt		$ 1,319	$ 403
7.25% Senior Notes due November 2025 | Subsequent Event
Subsequent events
Debt instrument face value	$ 750
Debt instrument interest rate stated percentage	7.25%
Proceeds from issuance of debt	$ 735
Redemption price of debt instrument (as a percent)	100.00%