Diamond Offshore Drilling (DODRW) 10-Q 30 Jul 18 2018 Q2 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2018	Jul. 27, 2018
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2018
Document Fiscal Year Focus	2,018
Document Fiscal Period Focus	Q2
Trading Symbol	DO
Entity Registrant Name	DIAMOND OFFSHORE DRILLING, INC.
Entity Central Index Key	949,039
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		137,434,458

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets (Unaudited) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 144,168	$ 376,037
Marketable securities	274,671
Accounts receivable, net of allowance for bad debts	203,131	256,730
Prepaid expenses and other current assets	154,408	157,625
Assets held for sale	67,815	96,261
Total current assets	844,193	886,653
Drilling and other property and equipment, net of accumulated depreciation	5,197,197	5,261,641
Other assets	71,389	102,276
Total assets	6,112,779	6,250,570
Current liabilities:
Accounts payable	54,717	38,755
Accrued liabilities	130,123	154,655
Taxes payable	14,522	29,878
Total current liabilities	199,362	223,288
Long-term debt	1,973,059	1,972,225
Deferred tax liability	124,350	167,299
Other liabilities	105,278	113,497
Total liabilities	2,402,049	2,476,309
Commitments and contingencies (Note 9)
Stockholders' equity:
Preferred stock (par value $0.01, 25,000,000 shares authorized, none issued and outstanding)
Common stock (par value $0.01, 500,000,000 shares authorized; 144,374,006 shares issued and 137,430,916 shares outstanding at June 30, 2018; 144,085,292 shares issued and 137,227,782 shares outstanding at December 31, 2017)	1,444	1,441
Additional paid-in capital	2,013,862	2,011,397
Retained earnings	1,899,735	1,964,497
Accumulated other comprehensive income (loss)	23	(5)
Treasury stock, at cost (6,943,090 and 6,857,510 shares of common stock at June 30, 2018 and December 31, 2017, respectively)	(204,334)	(203,069)
Total stockholders' equity	3,710,730	3,774,261
Total liabilities and stockholders' equity	$ 6,112,779	$ 6,250,570

Condensed Consolidated Balance3

Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - $ / shares	Jun. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Preferred stock, par value	$ 0.01	$ 0.01
Preferred stock, shares authorized	25,000,000	25,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	500,000,000	500,000,000
Common stock, shares issued	144,374,006	144,085,292
Common stock, shares outstanding	137,430,916	137,227,782
Treasury stock, shares	6,943,090	6,857,510

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Revenues:
Total revenues	$ 268,861	$ 399,289	$ 564,371	$ 773,515
Operating expenses:
Depreciation	81,825	85,982	163,650	179,211
General and administrative	18,236	19,010	36,749	36,493
Impairment of assets	27,225	71,268	27,225	71,268
Restructuring and separation costs	1,265		4,276
Gain on disposition of assets	(50)	(802)	(560)	(2,148)
Total operating expenses	321,236	378,465	616,234	701,832
Operating (loss) income	(52,375)	20,824	(51,863)	71,683
Other income (expense):
Interest income	2,001	396	3,638	571
Interest expense, net of amounts capitalized	(29,585)	(27,251)	(57,903)	(54,847)
Foreign currency transaction gain (loss)	411	(927)	858	160
Other, net	262	(62)	842	(125)
(Loss) income before income tax benefit	(79,286)	(7,020)	(104,428)	17,442
Income tax benefit	10,012	22,969	54,475	22,046
Net (loss) income	$ (69,274)	$ 15,949	$ (49,953)	$ 39,488
(Loss) earnings per share, Basic and Diluted	$ (0.50)	$ 0.12	$ (0.36)	$ 0.29
Weighted-average shares outstanding:
Shares of common stock	137,429	137,224	137,362	137,199
Dilutive potential shares of common stock		3		36
Total weighted-average shares outstanding	137,429	137,227	137,362	137,235
Contract Drilling [Member]
Revenues:
Total revenues	$ 265,353	$ 392,170	$ 553,279	$ 755,727
Operating expenses:
Contract drilling, excluding depreciation	189,321	196,217	374,010	399,740
Reimbursable Expenses [Member]
Revenues:
Total revenues	3,508	7,119	11,092	17,788
Operating expenses:
Contract drilling, excluding depreciation	$ 3,414	$ 6,790	$ 10,884	$ 17,268

Condensed Consolidated Stateme5

Condensed Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Statement of Comprehensive Income [Abstract]
Net (loss) income	$ (69,274)	$ 15,949	$ (49,953)	$ 39,488
Derivative financial instruments:
Reclassification adjustment for gain included in net income	(1)	(1)	(3)	(3)
Investments in marketable securities:
Unrealized holding gain	31		31
Total other comprehensive gain (loss)	30	(1)	28	(3)
Comprehensive (loss) income	$ (69,244)	$ 15,948	$ (49,925)	$ 39,485

Condensed Consolidated Stateme6

Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Operating activities:
Net (loss) income	$ (49,953)	$ 39,488
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation	163,650	179,211
Loss on impairment of assets	27,225	71,268
Restructuring and separation costs	2,184
Gain on disposition of assets	(560)	(2,148)
Deferred tax provision	(61,160)	(54,425)
Stock-based compensation expense	2,468	2,651
Contract liabilities, net	(3,255)	11,524
Contract assets, net	(956)
Deferred contract costs, net	24,703	16,866
Other assets, noncurrent	742	(1,619)
Other liabilities, noncurrent	(3,849)	407
Other	393	1,202
Changes in operating assets and liabilities:
Accounts receivable	53,451	(64,489)
Prepaid expenses and other current assets	28	(6,154)
Accounts payable and accrued liabilities	(21,466)	(12,291)
Taxes payable	(2,878)	(4,610)
Net cash provided by operating activities	130,767	176,881
Investing activities:
Capital expenditures	(90,432)	(71,889)
Proceeds from maturities of marketable securities	300,000
Purchase of marketable securities	(573,837)
Proceeds from disposition of assets, net of disposal costs	1,723	4,077
Other		23
Net cash used in investing activities	(362,546)	(67,789)
Financing activities:
Net repayment of short-term borrowings		(104,200)
Other	(90)	(156)
Net cash used in financing activities	(90)	(104,356)
Net change in cash and cash equivalents	(231,869)	4,736
Cash and cash equivalents, beginning of period	376,037	156,233
Cash and cash equivalents, end of period	$ 144,168	$ 160,969

General Information

General Information	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
General Information	1. General Information The unaudited condensed consolidated financial statements of Diamond Offshore Drilling, Inc. and subsidiaries, which we refer to as “Diamond Offshore,” “we,” “us” or “our,” should be read in conjunction with our Annual Report on Form 10-K No. 1-13926). As of July 27, 2018, Loews Corporation owned approximately 53% of the outstanding shares of our common stock. Interim Financial Information The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the U.S., or GAAP, for interim financial information and with the instructions to Form 10-Q S-X Use of Estimates in the Preparation of Financial Statements The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amount of revenues and expenses during the reporting period. Actual results could differ from those estimated. Changes in Accounting Principles Revenue Recognition No. 2014-09, Revenue from Contracts with Customers 2014-09, We adopted ASU 2014-09 Our adoption of ASU 2014-09 Income Taxes No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory, 2016-16. 2016-16 2016-16 The aggregate impact of the changes in accounting principles, as discussed above, to our unaudited Condensed Consolidated Balance Sheet on January 1, 2018 was as follows (in thousands): Retained Prepaid Expenses and Other Deferred Balance as of January 1, 2018 before adoption $ 1,964,497 $ 157,625 $ 102,276 $ 167,299 Adjustments for adoption of: Topic 606 2,590 611 2,107 128 ASU 2016-16 (17,401 ) — — 17,401 Balance as of January 1, 2018 after adoption $ 1,949,686 $ 158,236 $ 104,383 $ 184,828 Other Recently Adopted Accounting Pronouncements In February 2018, the FASB issued ASU No. 2018-02, Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income 2018-02. 2018-02 one-time 2018-02 2018-02 2018-02 tax-related 2018-02 In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments 2016-15. 2016-15 zero-coupon 2016-15 Recent Accounting Pronouncements Not Yet Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) 2016-02, 2016-02, 2016-02, non-lease Revenue from Contracts with Customers non-lease With respect to leases whereby we are the lessee, we expect to recognize lease liabilities and offsetting right of use assets corresponding to, at a minimum, our currently identified, undiscounted future minimum lease commitments of approximately $490 million, primarily related to certain leased subsea equipment. However, we are still evaluating the overall impact and will continue to refine our estimate prior to adoption of the ASU. We currently expect to elect the transition practical expedient package available in the ASU whereby we will not reassess (i) whether any of our expired or existing contracts contain a lease, (ii) the classification for any expired or existing leases and (iii) initial direct costs for any existing leases.

Revenue from Contracts with Cus

Revenue from Contracts with Customers	6 Months Ended
	Jun. 30, 2018
Revenue from Contract with Customer [Abstract]
Revenue from Contracts with Customers	2. Revenue from Contracts with Customers The activities that primarily drive the revenue earned from our drilling contracts include (i) providing a drilling rig and the crew and supplies necessary to operate the rig, (ii) mobilizing and demobilizing the rig to and from the drill site and (iii) performing rig preparation activities and/or modifications required for the contract. Consideration received for performing these activities may consist of dayrate drilling revenue, mobilization and demobilization revenue, contract preparation revenue and reimbursement revenue. We account for these integrated services provided within our drilling contracts as a single performance obligation satisfied over time and comprised of a series of distinct time increments in which we provide drilling services. Consideration for activities that are not distinct within the context of our contracts and do not correspond to a distinct time increment within the contract term are allocated across the single performance obligation and recognized ratably as time elapses over the initial term of the contract (which is the period we estimate to be benefited from the corresponding activities and generally ranges from two to 60 months). Consideration for activities that correspond to a distinct time increment within the contract term is recognized in the period when the services are performed. The total transaction price is determined for each individual contract by estimating both fixed and variable consideration expected to be earned over the term of the contract. See below for further discussion regarding the allocation of the transaction price to the remaining performance obligations. The amount estimated for variable consideration may be constrained (reduced) and is only included in the transaction price to the extent that it is probable that a significant reversal of previously recognized revenue will not occur throughout the term of the contract. When determining if variable consideration should be constrained, management considers whether there are factors outside of our control that could result in a significant reversal of revenue as well as the likelihood and magnitude of a potential reversal of revenue. These estimates are re-assessed Dayrate Drilling Revenue. Mobilization/Demobilization Revenue. lump-sum In some contracts, there is uncertainty as to the likelihood and amount of expected demobilization revenue to be received. For example, contractual provisions may require that a rig demobilize a certain distance before the demobilization revenue is payable or the amount may vary dependent upon whether or not the rig has additional contracted work within a certain distance from the wellsite. Therefore, the estimate for such revenue may be constrained, as described above, depending on the facts and circumstances pertaining to the specific contract. We assess the likelihood of receiving such revenue based on past experience and knowledge of the market conditions. Contract Preparation Revenue. lump-sum Capital Modification Revenue lump-sum Revenues Related to Reimbursable Expenses Contract Balances Accounts receivable are recognized when the right to consideration becomes unconditional based upon contractual billing schedules. Payment terms on invoiced amounts are typically 30 days. Contract asset balances consist primarily of demobilization revenue that we expect to receive and is recognized ratably throughout the contract term, but invoiced upon completion of the demobilization activities. Once the demobilization revenue is invoiced, the corresponding contract asset is transferred to accounts receivable. Contract liabilities include payments received for mobilization as well as rig preparation and upgrade activities which are allocated to the overall performance obligation and recognized ratably over the initial term of the contract. Contract balances are netted at a contract level, such that deferred revenue for mobilization, contract preparation and capital modifications (contract liabilities) is netted with any accrued demobilization revenue (contract asset) for each applicable contract. The following table provides information about receivables, contract assets and contract liabilities from our contracts with customers (in thousands): June 30, January 1, 2018 2018 Trade receivables $ 194,425 $ 247,453 Current contract assets (1) 1,567 611 Noncurrent contract assets (1) 2,107 2,107 Current contract liabilities (deferred revenue) (1) (10,173 ) (11,371 ) Noncurrent contract liabilities (deferred revenue) (1) (6,915 ) (8,972 ) (1) Contract assets and contract liabilities may reflect balances that have been netted together on a contract basis. Net current contract asset and liability balances are included in “Prepaid expenses and other current assets” and “Accrued liabilities,” respectively, and net noncurrent contract asset and liability balances are included in “Other assets” and “Other liabilities,” respectively, in our unaudited Condensed Consolidated Balance Sheet as of June 30, 2018. Significant changes in the contract assets and the contract liabilities balances during the period are as follows (in thousands): Net Contract Contract assets at January 1, 2018 $ 2,718 Contract liabilities at January 1, 2018 (20,343 ) Net balance at January 1, 2018 (17,625 ) Decrease due to amortization of revenue that was included in the beginning contract liability balance 7,048 Increase due to cash received, excluding amounts recognized as revenue during the period (4,670 ) Increase due to revenue recognized during the period but contingent on future performance 2,306 Decrease due to transfer to receivables during the period (611 ) Adjustments 138 Net balance at June 30, 2018 $ (13,414 ) Contract assets at June 30, 2018 $ 3,674 Contract liabilities at June 30, 2018 (17,088 ) Deferred Contract Costs Certain direct and incremental costs incurred for upfront preparation, initial mobilization and modifications of contracted rigs represent costs of fulfilling a contract as they relate directly to a contract, enhance resources that will be used in satisfying our performance obligations in the future and are expected to be recovered. Such costs are deferred and amortized ratably to contract drilling expense as services are rendered over the initial term of the related drilling contract. Such deferred contract costs in the amount of $56.1 million and $25.1 million are reported in “Prepaid expenses and other current assets” and “Other assets,” respectively, in our unaudited Condensed Consolidated Balance Sheet at June 30, 2018. During the three-month and six-month Costs incurred for the demobilization of rigs at contract completion are recognized as incurred during the demobilization process. Costs incurred for rig modifications or upgrades required for a contract, which are considered to be capital improvements, are capitalized as drilling and other property and equipment and depreciated over the estimated useful life of the improvement. Transaction Price Allocated to Remaining Performance Obligations The following table reflects revenue expected to be recognized in the future related to unsatisfied performance obligations as of June 30, 2018 (in thousands): For the Years Ending December 31, 2018 (1) 2019 2020 2021 Total Mobilization and contract preparation revenue $ 9,115 $ 9,043 $ 81 $ — $ 18,239 Capital modification revenue 6,598 9,170 387 — 16,155 Demobilization revenue 2,170 — — — 2,170 Other deferred revenue 343 681 681 194 1,899 Total $ 18,226 $ 18,894 $ 1,149 $ 194 $ 38,463 (1) Represents the six-month The revenue included above consists primarily of expected fixed mobilization, demobilization, and upgrade revenue for both wholly and partially unsatisfied performance obligations as well as expected variable mobilization, demobilization, and upgrade revenue for partially unsatisfied performance obligations, which has been estimated for purposes of allocating across the entire corresponding performance obligations. The amounts are derived from the specific terms within drilling contracts that contain such provisions, and the expected timing for recognition of such revenue is based on the estimated start date and duration of each respective contract based on information known at June 30, 2018. The actual timing of recognition of such amounts may vary due to factors outside of our control. We have applied the disclosure practical expedient in ASC 606-10-50-14A(b) Impact of Topic 606 on Financial Statement Line Items Our revenue recognition pattern under Topic 606 is similar to revenue recognition under the previous guidance, except for the recognition of demobilization revenue. Such revenue, which was recognized upon completion of a contract under the previous guidance, is now estimated at contract inception and recognized ratably as contract drilling revenue over the term of the contract with an offset to a contract asset under Topic 606. The following tables summarize the impacts of adopting Topic 606 on our selected unaudited Condensed Consolidated Balance Sheets, Statements of Operations and Statements of Cash Flows information, as of and for the six months ended June 30, 2018 (in thousands, except per share data): June 30, 2018 Balances as reported Adjustments Balances Unaudited Condensed Consolidated Balance Sheets Prepaid and other current assets $ 154,408 $ (1,174 ) $ 153,234 Other assets 71,389 (2,107 ) 69,282 Accrued liabilities 130,123 739 130,862 Deferred tax liability 124,350 (402 ) 123,948 Retained earnings 1,899,735 (3,619 ) 1,896,116 Unaudited Condensed Consolidated Statements of Operations Contract drilling revenue $ 553,279 $ (1,303 ) $ 551,976 Income tax benefit 54,475 274 54,749 Loss per share, Basic and Diluted (0.36 ) (0.01 ) (0.37 ) Unaudited Condensed Consolidated Statements of Cash Flows Cash flow from operating activities: Net loss $ (49,953 ) $ (1,029 ) $ (50,982 ) Adjustments to reconcile net loss to net cash Deferred tax provision (61,160 ) (274 ) (61,434 ) Contract liabilities (3,255 ) 739 (2,516 ) Contract assets (956 ) 564 (392 )

Impairment of Assets

Impairment of Assets	6 Months Ended
	Jun. 30, 2018
Goodwill and Intangible Assets Disclosure [Abstract]
Impairment of Assets	3. Impairment of Assets 2018 Impairment. Ocean Scepter jack-up jack-up Ocean Scepter During the second quarter of 2018, we evaluated four of our drilling rigs with indicators of impairment. Based on our assumptions and analysis at that time, we determined that the undiscounted probability-weighted cash flow for each rig was in excess of its respective carrying value. As a result, we concluded that no impairment of these rigs had occurred at June 30, 2018. As of June 30, 2018, there were nine rigs in our drilling fleet, not previously written down to scrap, for which there were no current indicators that their carrying amounts may not be recoverable and, thus, were not evaluated for impairment. If market fundamentals in the offshore oil and gas industry deteriorate further or a projected market recovery is further delayed, we may be required to recognize additional impairment losses in future periods. 2017 Impairments. We estimated the fair value of the 2017 Impaired Rigs using an income approach, whereby the fair value of each rig was estimated based on a calculation of the rig’s future net cash flows. These calculations utilized significant unobservable inputs, including estimated proceeds that may be received on ultimate disposition of the rig, and are representative of Level 3 fair value measurements due to the significant level of estimation involved and lack of transparency as to the inputs used. During the second quarter of 2017, we recorded an impairment loss of $71.3 million related to our 2017 Impaired Rigs.

Supplemental Financial Informat

Supplemental Financial Information	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Supplemental Financial Information	4. Supplemental Financial Information Condensed Consolidated Balance Sheets Information Accounts receivable, net of allowance for bad debts, consist of the following (in thousands): June 30, December 31, 2018 2017 Trade receivables $ 194,425 $ 247,453 Value added tax receivables 13,645 14,067 Related party receivables 113 205 Other 407 464 208,590 262,189 Allowance for bad debts (5,459 ) (5,459 ) Total $ 203,131 $ 256,730 Prepaid expenses and other current assets consist of the following (in thousands): June 30, December 31, 2018 2017 Rig spare parts and supplies $ 23,887 $ 28,383 Deferred contract costs 56,110 51,297 Prepaid BOP lease 3,873 3,873 Prepaid insurance 4,407 3,091 Prepaid taxes 58,417 67,212 Other 7,714 3,769 Total $ 154,408 $ 157,625 Accrued liabilities consist of the following (in thousands): June 30, December 31, 2018 2017 Rig operating expenses $ 30,055 $ 48,894 Payroll and benefits 32,929 46,560 Deferred revenue 10,173 11,371 Accrued capital project/upgrade costs 12,714 3,698 Interest payable 28,234 28,234 Personal injury and other claims 6,048 5,699 Other 9,970 10,199 Total $ 130,123 $ 154,655 Includes $2.2 million and $13.6 million in accrued costs at June 30, 2018 and December 31, 2017, respectively, related to a restructuring plan that was implemented in late 2017. See Note 10. Condensed Consolidated Statements of Cash Flows Information Noncash investing activities excluded from the unaudited Condensed Consolidated Statements of Cash Flows and other supplemental cash flow information is as follows (in thousands): Six Months Ended June 30, 2018 2017 Accrued but unpaid capital expenditures at period end $ 12,714 $ 3,649 Common stock withheld for payroll tax obligations (1) 1,265 473 Cash interest payments 56,531 51,603 Cash income taxes paid, net of (refunds): Foreign 4,035 33,319 State 2 94 (1) Represents the cost of 85,580 shares and 28,386 shares of common stock withheld to satisfy payroll tax obligations incurred as a result of the vesting of restricted stock units in the six months ended June 30, 2018 and 2017, respectively. These costs for the six months ended June 30, 2018 are presented as a deduction from stockholders’ equity in “Treasury stock” in our unaudited Condensed Consolidated Balance Sheets at June 30, 2018.

Earnings (Loss) Per Share

Earnings (Loss) Per Share	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Earnings (Loss) Per Share	5. Earnings (Loss) Per Share A reconciliation of the numerators and the denominators of our basic and diluted per-share Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Net (loss) income – basic and diluted numerator $ (69,274 ) $ 15,949 $ (49,953 ) $ 39,488 Weighted average shares – basic (denominator): 137,429 137,224 137,362 137,199 Dilutive effect of stock-based awards — 3 — 36 Weighted average shares including conversions – diluted (denominator) 137,429 137,227 137,362 137,235 (Loss) earnings per share: Basic $ (0.50 ) $ 0.12 $ (0.36 ) $ 0.29 Diluted $ (0.50 ) $ 0.12 $ (0.36 ) $ 0.29 The following table sets forth the share effects of stock-based awards excluded from the computations of diluted (loss) earnings per share, as the inclusion of such potentially dilutive shares would have been antidilutive for the periods presented (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Employee and director: Stock options — — — 1 Stock appreciation rights 1,144 1,301 1,207 1,355 Restricted stock units 1,194 1,274 1,133 933

Marketable Securities

Marketable Securities	6 Months Ended
	Jun. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Marketable Securities	6. Marketable Securities We report our investments as current assets in our unaudited Condensed Balance Sheets in “Marketable securities,” representing the investment of cash available for current operations. See Note 7. Our investments in marketable securities are classified as available for sale and are summarized as follows (in thousands): June 30, 2018 Amortized Unrealized Market U.S. Treasury bills (due within one year) $ 274,636 $ 35 $ 274,671 Proceeds from maturities of U.S. Treasury bills were $300.0 million during the three-month and six-month six-month

Financial Instruments and Fair

Financial Instruments and Fair Value Disclosures	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Financial Instruments and Fair Value Disclosures	7. Financial Instruments and Fair Value Disclosures Financial instruments that potentially subject us to significant concentrations of credit or market risk consist primarily of periodic temporary investments of excess cash, trade accounts receivable and investments in debt securities. We generally place our excess cash investments in U.S. Treasury bills and U.S. government-backed short-term money market instruments through several financial institutions. We periodically evaluate the relative credit standing of these financial institutions as part of our investment strategy. Concentrations of credit risk with respect to our trade accounts receivable are limited primarily due to the entities comprising our customer base. Since the market for our services is the offshore oil and gas industry, this customer base has consisted primarily of major and independent oil and gas companies and government-owned oil companies. Based on our current customer base and the geographic areas in which we operate, we do not believe that we have any significant concentrations of credit risk at June 30, 2018. In general, before working for a customer with whom we have not had a prior business relationship and/or whose financial stability may be uncertain to us, we perform a credit review on that company. Based on that analysis, we may require that the customer present a letter of credit, prepay or provide other credit enhancements. We record a provision for bad debts on a case-by-case Fair Values Fair value is defined as the exchange price that would be received for an asset or paid to transfer a liability (an exit price) in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. The fair value hierarchy prescribed by GAAP requires an entity to maximize the use of observable inputs and minimize the use of unobservable inputs when measuring fair value. There are three levels of inputs that may be used to measure fair value: Level 1 Quoted prices for identical instruments in active markets. Level 1 assets include short-term investments such as money market funds and U.S. Treasury bills. Our Level 1 assets at June 30, 2018 consisted of cash held in money market funds of $114.0 million, time deposits of $20.9 million and investments in U.S. Treasury bills of $274.7 million. Our Level 1 assets at December 31, 2017 consisted of cash held in money market funds of $337.1 million and time deposits of $20.9 million. Level 2 Quoted market prices for similar instruments in active markets; quoted prices for identical or similar instruments in markets that are not active; and model-derived valuations in which all significant inputs and significant value drivers are observable in active markets. We had no Level 2 assets or liabilities as of June 30, 2018 or December 31, 2017. Level 3 Valuations derived from valuation techniques in which one or more significant inputs or significant value drivers are unobservable. Level 3 assets and liabilities generally include financial instruments whose value is determined using pricing models, discounted cash flow methodologies, or similar techniques, as well as instruments for which the determination of fair value requires significant management judgment or estimation or for which there is a lack of transparency as to the inputs used. Our Level 3 assets at June 30, 2018 and December 31, 2017 consisted of nonrecurring measurements of certain of our drilling rigs for which we recorded impairment losses during 2018 and 2017. Market conditions could cause an instrument to be reclassified among Levels 1, 2 and 3. Our policy regarding fair value measurements of financial instruments transferred into and out of levels is to reflect the transfers as having occurred at the beginning of the reporting period. There were no transfers between fair value levels during the six-month Certain of our assets and liabilities are required to be measured at fair value on a recurring basis in accordance with GAAP. In addition, certain assets and liabilities may be recorded at fair value on a nonrecurring basis. Generally, we record assets at fair value on a nonrecurring basis as a result of impairment charges. We recorded impairment charges related to certain of our drilling rigs, which were measured at fair value on a nonrecurring basis, during the six-month Assets and liabilities measured at fair value are summarized below (in thousands). June 30, 2018 Fair Value Measurements Using Level 1 Level 2 Level 3 Assets at Total for Period (1) Recurring fair value measurements: Assets: Short-term investments $ 409,616 $ — $ — $ 409,616 Nonrecurring fair value measurements: Assets: Impaired assets (2) $ — $ — $ 67,815 $ 67,815 $ 27,225 (1) Represents impairment loss of $27.2 million recognized during the second quarter of 2018 related to a jack-up (2) Represents the total book value as of June 30, 2018 of a jack-up December 31, 2017 Fair Value Measurements Using Level 1 Level 2 Level 3 Assets at Total for Year (1) Recurring fair value measurements: Assets: Short-term investments $ 358,019 $ — $ — $ 358,019 Nonrecurring fair value measurements: Assets: Impaired assets (2) $ — $ — $ 97,261 $ 97,261 $ 99,313 (1) Represents impairment losses of $71.3 million and $28.0 million recognized during the second and fourth quarters of 2017, respectively, related to three drilling rigs whose carrying values were impaired. See Note 3. (2) Represents the total book value as of December 31, 2017 of two floaters, which were written down to their estimated fair values during the second quarter of 2017, and one jack-up We believe that the carrying amounts of our other financial assets and liabilities (excluding long-term debt), which are not measured at fair value in our unaudited Condensed Consolidated Balance Sheets, approximate fair value based on the following assumptions: • Cash and cash equivalents • Accounts receivable and accounts payable We consider our senior notes to be Level 2 liabilities under the GAAP fair value hierarchy and, accordingly, the fair value of our senior notes was derived using a third-party pricing service at June 30, 2018 and December 31, 2017. We perform control procedures over information we obtain from pricing services and brokers to test whether prices received represent a reasonable estimate of fair value. These procedures include the review of pricing service or broker pricing methodologies and comparing fair value estimates to actual trade activity executed in the market for these instruments occurring generally within a 10-day June 30, 2018 December 31, 2017 Fair Value Carrying Value Fair Value Carrying Value 3.45% Senior Notes due 2023 $ 221.9 $ 249.4 $ 223.1 $ 249.4 7.875% Senior Notes due 2025 518.1 496.6 523.1 496.5 5.70% Senior Notes due 2039 400.0 497.2 405.0 497.2 4.875% Senior Notes due 2043 540.0 748.9 547.5 748.9 We have estimated the fair value amounts by using appropriate valuation methodologies and information available to management. Considerable judgment is required in developing these estimates, and accordingly, no assurance can be given that the estimated values are indicative of the amounts that would be realized in a free market exchange.

Drilling and Other Property and

Drilling and Other Property and Equipment	6 Months Ended
	Jun. 30, 2018
Property, Plant and Equipment [Abstract]
Drilling and Other Property and Equipment	8. Drilling and Other Property and Equipment Cost and accumulated depreciation of drilling and other property and equipment are summarized as follows (in thousands): June 30, December 31, 2018 2017 Drilling rigs and equipment $ 8,064,663 $ 7,971,406 Land and buildings 63,554 63,309 Office equipment and other 87,702 82,691 Cost 8,215,919 8,117,406 Less: accumulated depreciation (3,018,722 ) (2,855,765 ) Drilling and other property and equipment, net $ 5,197,197 $ 5,261,641

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
	Jun. 30, 2018
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	9. Commitments and Contingencies Various claims have been filed against us in the ordinary course of business, including claims by offshore workers alleging personal injuries. With respect to each claim or exposure, we have made an assessment, in accordance with GAAP, of the probability that the resolution of the matter would ultimately result in a loss. When we determine that an unfavorable resolution of a matter is probable and such amount of loss can be reasonably estimated, we record a liability for the amount of the reasonably estimated loss at the time that both of these criteria are met. Our management believes that we have recorded adequate accruals for any liabilities that may reasonably be expected to result from these claims. Patent Litigation Ocean BlackHawk Ocean BlackHornet Ocean BlackRhino Ocean BlackLion Asbestos Litigation Other Litigation. Personal Injury Claims The Jones Act is a federal law that permits seamen to seek compensation for certain injuries during the course of their employment on a vessel and governs the liability of vessel operators and marine employers for the work-related injury or death of an employee. We engage outside consultants to assist us in estimating our aggregate liability for personal injury claims based on our historical losses and utilizing various actuarial models. We allocate a portion of the aggregate liability to “Accrued liabilities” based on an estimate of claims expected to be paid within the next twelve months with the residual recorded as “Other liabilities.” At June 30, 2018 our estimated liability for personal injury claims was $29.0 million, of which $5.3 million and $23.7 million were recorded in “Accrued liabilities” and “Other liabilities,” respectively, in our unaudited Condensed Consolidated Balance Sheets. At December 31, 2017 our estimated liability for personal injury claims was $30.9 million, of which $5.2 million and $25.7 million were recorded in “Accrued liabilities” and “Other liabilities,” respectively, in our Consolidated Balance Sheets. The eventual settlement or adjudication of these claims could differ materially from our estimated amounts due to uncertainties such as: • the severity of personal injuries claimed; • significant changes in the volume of personal injury claims; • the unpredictability of legal jurisdictions where the claims will ultimately be litigated; • inconsistent court decisions; and • the risks and lack of predictability inherent in personal injury litigation. Letters of Credit and Other.

Restructuring and Separation Co

Restructuring and Separation Costs	6 Months Ended
	Jun. 30, 2018
Restructuring and Related Activities [Abstract]
Restructuring and Separation Costs	10. Restructuring and Separation Costs In late 2017, our management approved and initiated a plan to restructure our worldwide operations, which included a reduction in workforce at our corporate facilities and onshore bases that we refer to as the 2017 Reduction Plan. During the three-month and six-month

Income Taxes

Income Taxes	6 Months Ended
	Jun. 30, 2018
Income Tax Disclosure [Abstract]
Income Taxes	11. Income Taxes Effective January 1, 2018, we adopted ASU 2016-16, Additionally, in response to our interpretation of the Tax Reform Act, which was signed into law in late December 2017, we recorded a provisional net tax expense of $1.1 million during the fourth quarter of 2017, which included a charge relating to the one-time non-US We are still in the process of evaluating our estimate as it relates to the tax effect of (i) the mandatory, deemed repatriation aspect of the Tax Reform Act, (ii) the amount of deferred tax assets and liabilities subject to the income tax rate change from 35% to 21% and (iii) the ability to more likely than not realize the benefit of deferred tax assets, including net operating losses and foreign tax credits. We will continue to monitor developments in these areas and adjust our estimates throughout 2018, as and if necessary, as additional guidance and clarification becomes available.

Segments and Geographic Area An

Segments and Geographic Area Analysis	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Segments and Geographic Area Analysis	12. Segments and Geographic Area Analysis Although we provide contract drilling services with different types of offshore drilling rigs and also provide such services in many geographic locations, we have aggregated these operations into one reportable segment based on the similarity of economic characteristics due to the nature of the revenue-earning process as it relates to the offshore drilling industry over the operating lives of our drilling rigs. Our drilling rigs are highly mobile and may be moved to other markets throughout the world in response to market conditions or customer needs. At June 30, 2018, our active drilling rigs were located offshore four countries in addition to the United States. Revenues by geographic area are presented by attributing revenues to the individual country or areas where the services were performed. The following tables provide information about disaggregated revenue by equipment-type and primary geographical market (in thousands): Three Months Ended June 30, 2018 Floater Jack-up (1) Total Revenues Total United States $ 158,554 $ 3,648 $ 162,202 $ 1,172 $ 163,374 South America 26,288 — 26,288 — 26,288 Europe 18,738 — 18,738 1,742 20,480 Australia/Asia 58,125 — 58,125 594 58,719 Total $ 261,705 $ 3,648 $ 265,353 $ 3,508 $ 268,861 (1) Loss-of-hire jack-up Six Months Ended June 30, 2018 Floater Jack-up (1) Total Revenues Total United States $ 318,228 $ 8,413 $ 326,641 $ 3,309 $ 329,950 South America 80,556 — 80,556 1 80,557 Europe 30,130 — 30,130 3,120 33,250 Australia/Asia 115,952 — 115,952 4,662 120,614 Total $ 544,866 $ 8,413 $ 553,279 $ 11,092 $ 564,371 (1) Loss-of-hire jack-up Three Months Ended June 30, 2017 Floater Jack-up Total Revenues Total United States $ 157,069 $ — $ 157,069 $ 2,335 $ 159,404 South America 111,498 — 111,498 (240 ) 111,258 Europe 44,533 — 44,533 1,194 45,727 Australia/Asia 72,883 — 72,883 3,593 76,476 Mexico — 6,187 6,187 237 6,424 Total $ 385,983 $ 6,187 $ 392,170 $ 7,119 $ 399,289 Six Months Ended June 30, 2017 Floater Jack-up Total Revenues Total United States $ 292,668 $ — $ 292,668 $ 4,456 $ 297,124 South America 214,179 — 214,179 (222 ) 213,957 Europe 100,268 — 100,268 3,159 103,427 Australia/Asia 138,561 — 138,561 10,009 148,570 Mexico — 10,051 10,051 386 10,437 Total $ 745,676 $ 10,051 $ 755,727 $ 17,788 $ 773,515

General Information (Policies)

General Information (Policies)	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Interim Financial Information	Interim Financial Information The accompanying unaudited condensed consolidated financial statements have been prepared in accordance with generally accepted accounting principles in the U.S., or GAAP, for interim financial information and with the instructions to Form 10-Q S-X
Use of Estimates in the Preparation of Financial Statements	Use of Estimates in the Preparation of Financial Statements The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements and the reported amount of revenues and expenses during the reporting period. Actual results could differ from those estimated.
Changes in Accounting Principles	Changes in Accounting Principles Revenue Recognition No. 2014-09, Revenue from Contracts with Customers 2014-09, We adopted ASU 2014-09 Our adoption of ASU 2014-09 Income Taxes No. 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory, 2016-16. 2016-16 2016-16 The aggregate impact of the changes in accounting principles, as discussed above, to our unaudited Condensed Consolidated Balance Sheet on January 1, 2018 was as follows (in thousands): Retained Prepaid Expenses and Other Deferred Balance as of January 1, 2018 before adoption $ 1,964,497 $ 157,625 $ 102,276 $ 167,299 Adjustments for adoption of: Topic 606 2,590 611 2,107 128 ASU 2016-16 (17,401 ) — — 17,401 Balance as of January 1, 2018 after adoption $ 1,949,686 $ 158,236 $ 104,383 $ 184,828
Recently Adopted Accounting Pronouncements	Other Recently Adopted Accounting Pronouncements In February 2018, the FASB issued ASU No. 2018-02, Income Statement—Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income 2018-02. 2018-02 one-time 2018-02 2018-02 2018-02 tax-related 2018-02 In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230): Classification of Certain Cash Receipts and Cash Payments 2016-15. 2016-15 zero-coupon 2016-15
Recent Accounting Pronouncements Not Yet Adopted	Recent Accounting Pronouncements Not Yet Adopted In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842) 2016-02, 2016-02, 2016-02, non-lease Revenue from Contracts with Customers non-lease With respect to leases whereby we are the lessee, we expect to recognize lease liabilities and offsetting right of use assets corresponding to, at a minimum, our currently identified, undiscounted future minimum lease commitments of approximately $490 million, primarily related to certain leased subsea equipment. However, we are still evaluating the overall impact and will continue to refine our estimate prior to adoption of the ASU. We currently expect to elect the transition practical expedient package available in the ASU whereby we will not reassess (i) whether any of our expired or existing contracts contain a lease, (ii) the classification for any expired or existing leases and (iii) initial direct costs for any existing leases.

General Information (Tables)

General Information (Tables)	6 Months Ended
	Jun. 30, 2018
Accounting Policies [Abstract]
Summary of Aggregate Impact of Changes in Accounting Principles	The aggregate impact of the changes in accounting principles, as discussed above, to our unaudited Condensed Consolidated Balance Sheet on January 1, 2018 was as follows (in thousands): Retained Prepaid Expenses and Other Deferred Balance as of January 1, 2018 before adoption $ 1,964,497 $ 157,625 $ 102,276 $ 167,299 Adjustments for adoption of: Topic 606 2,590 611 2,107 128 ASU 2016-16 (17,401 ) — — 17,401 Balance as of January 1, 2018 after adoption $ 1,949,686 $ 158,236 $ 104,383 $ 184,828

Revenue from Contracts with C21

Revenue from Contracts with Customers (Tables)	6 Months Ended
	Jun. 30, 2018
Revenue from Contract with Customer [Abstract]
Summary of Information about Receivables, Contract Assets and Contract Liabilities from Contracts with Customers	The following table provides information about receivables, contract assets and contract liabilities from our contracts with customers (in thousands): June 30, January 1, 2018 2018 Trade receivables $ 194,425 $ 247,453 Current contract assets (1) 1,567 611 Noncurrent contract assets (1) 2,107 2,107 Current contract liabilities (deferred revenue) (1) (10,173 ) (11,371 ) Noncurrent contract liabilities (deferred revenue) (1) (6,915 ) (8,972 ) (1) Contract assets and contract liabilities may reflect balances that have been netted together on a contract basis. Net current contract asset and liability balances are included in “Prepaid expenses and other current assets” and “Accrued liabilities,” respectively, and net noncurrent contract asset and liability balances are included in “Other assets” and “Other liabilities,” respectively, in our unaudited Condensed Consolidated Balance Sheet as of June 30, 2018.
Summary of Significant Changes in Contract Assets and Contract Liabilities Balances	Significant changes in the contract assets and the contract liabilities balances during the period are as follows (in thousands): Net Contract Contract assets at January 1, 2018 $ 2,718 Contract liabilities at January 1, 2018 (20,343 ) Net balance at January 1, 2018 (17,625 ) Decrease due to amortization of revenue that was included in the beginning contract liability balance 7,048 Increase due to cash received, excluding amounts recognized as revenue during the period (4,670 ) Increase due to revenue recognized during the period but contingent on future performance 2,306 Decrease due to transfer to receivables during the period (611 ) Adjustments 138 Net balance at June 30, 2018 $ (13,414 ) Contract assets at June 30, 2018 $ 3,674 Contract liabilities at June 30, 2018 (17,088 )
Summary of Revenue Expected to be Recognized in Future Related to Unsatisfied Performance Obligations	The following table reflects revenue expected to be recognized in the future related to unsatisfied performance obligations as of June 30, 2018 (in thousands): For the Years Ending December 31, 2018 (1) 2019 2020 2021 Total Mobilization and contract preparation revenue $ 9,115 $ 9,043 $ 81 $ — $ 18,239 Capital modification revenue 6,598 9,170 387 — 16,155 Demobilization revenue 2,170 — — — 2,170 Other deferred revenue 343 681 681 194 1,899 Total $ 18,226 $ 18,894 $ 1,149 $ 194 $ 38,463 (1) Represents the six-month
Summary of Impacts of Adopting Topic 606 on Condensed Consolidated Balance Sheet, Statement of Operations and Cash Flows Information	The following tables summarize the impacts of adopting Topic 606 on our selected unaudited Condensed Consolidated Balance Sheets, Statements of Operations and Statements of Cash Flows information, as of and for the six months ended June 30, 2018 (in thousands, except per share data): June 30, 2018 Balances as reported Adjustments Balances Unaudited Condensed Consolidated Balance Sheets Prepaid and other current assets $ 154,408 $ (1,174 ) $ 153,234 Other assets 71,389 (2,107 ) 69,282 Accrued liabilities 130,123 739 130,862 Deferred tax liability 124,350 (402 ) 123,948 Retained earnings 1,899,735 (3,619 ) 1,896,116 Unaudited Condensed Consolidated Statements of Operations Contract drilling revenue $ 553,279 $ (1,303 ) $ 551,976 Income tax benefit 54,475 274 54,749 Loss per share, Basic and Diluted (0.36 ) (0.01 ) (0.37 ) Unaudited Condensed Consolidated Statements of Cash Flows Cash flow from operating activities: Net loss $ (49,953 ) $ (1,029 ) $ (50,982 ) Adjustments to reconcile net loss to net cash Deferred tax provision (61,160 ) (274 ) (61,434 ) Contract liabilities (3,255 ) 739 (2,516 ) Contract assets (956 ) 564 (392 )

Supplemental Financial Inform22

Supplemental Financial Information (Tables)	6 Months Ended
	Jun. 30, 2018
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accounts Receivable, Net of Allowance for Doubtful Accounts	Accounts receivable, net of allowance for bad debts, consist of the following (in thousands): June 30, December 31, 2018 2017 Trade receivables $ 194,425 $ 247,453 Value added tax receivables 13,645 14,067 Related party receivables 113 205 Other 407 464 208,590 262,189 Allowance for bad debts (5,459 ) (5,459 ) Total $ 203,131 $ 256,730
Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consist of the following (in thousands): June 30, December 31, 2018 2017 Rig spare parts and supplies $ 23,887 $ 28,383 Deferred contract costs 56,110 51,297 Prepaid BOP lease 3,873 3,873 Prepaid insurance 4,407 3,091 Prepaid taxes 58,417 67,212 Other 7,714 3,769 Total $ 154,408 $ 157,625
Accrued Liabilities	Accrued liabilities consist of the following (in thousands): June 30, December 31, 2018 2017 Rig operating expenses $ 30,055 $ 48,894 Payroll and benefits 32,929 46,560 Deferred revenue 10,173 11,371 Accrued capital project/upgrade costs 12,714 3,698 Interest payable 28,234 28,234 Personal injury and other claims 6,048 5,699 Other 9,970 10,199 Total $ 130,123 $ 154,655
Noncash Investing and Financing Activities	Noncash investing activities excluded from the unaudited Condensed Consolidated Statements of Cash Flows and other supplemental cash flow information is as follows (in thousands): Six Months Ended June 30, 2018 2017 Accrued but unpaid capital expenditures at period end $ 12,714 $ 3,649 Common stock withheld for payroll tax obligations (1) 1,265 473 Cash interest payments 56,531 51,603 Cash income taxes paid, net of (refunds): Foreign 4,035 33,319 State 2 94 (1) Represents the cost of 85,580 shares and 28,386 shares of common stock withheld to satisfy payroll tax obligations incurred as a result of the vesting of restricted stock units in the six months ended June 30, 2018 and 2017, respectively. These costs for the six months ended June 30, 2018 are presented as a deduction from stockholders’ equity in “Treasury stock” in our unaudited Condensed Consolidated Balance Sheets at June 30, 2018.

Earnings (Loss) Per Share (Tabl

Earnings (Loss) Per Share (Tables)	6 Months Ended
	Jun. 30, 2018
Earnings Per Share [Abstract]
Reconciliation of Numerators and Denominators of Basic and Diluted Per-Share Computations	A reconciliation of the numerators and the denominators of our basic and diluted per-share Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Net (loss) income – basic and diluted numerator $ (69,274 ) $ 15,949 $ (49,953 ) $ 39,488 Weighted average shares – basic (denominator): 137,429 137,224 137,362 137,199 Dilutive effect of stock-based awards — 3 — 36 Weighted average shares including conversions – diluted (denominator) 137,429 137,227 137,362 137,235 (Loss) earnings per share: Basic $ (0.50 ) $ 0.12 $ (0.36 ) $ 0.29 Diluted $ (0.50 ) $ 0.12 $ (0.36 ) $ 0.29
Securities Excluded from Computations of Diluted Earnings Per Share	The following table sets forth the share effects of stock-based awards excluded from the computations of diluted (loss) earnings per share, as the inclusion of such potentially dilutive shares would have been antidilutive for the periods presented (in thousands): Three Months Ended June 30, Six Months Ended June 30, 2018 2017 2018 2017 Employee and director: Stock options — — — 1 Stock appreciation rights 1,144 1,301 1,207 1,355 Restricted stock units 1,194 1,274 1,133 933

Marketable Securities (Tables)

Marketable Securities (Tables)	6 Months Ended
	Jun. 30, 2018
Investments, Debt and Equity Securities [Abstract]
Schedule of Marketable Securities	Our investments in marketable securities are classified as available for sale and are summarized as follows (in thousands): June 30, 2018 Amortized Unrealized Market U.S. Treasury bills (due within one year) $ 274,636 $ 35 $ 274,671

Financial Instruments and Fai25

Financial Instruments and Fair Value Disclosures (Tables)	6 Months Ended
	Jun. 30, 2018
Fair Value Disclosures [Abstract]
Assets and Liabilities Measured at Fair Value on Recurring and Nonrecurring Basis	Assets and liabilities measured at fair value are summarized below (in thousands). June 30, 2018 Fair Value Measurements Using Level 1 Level 2 Level 3 Assets at Total for Period (1) Recurring fair value measurements: Assets: Short-term investments $ 409,616 $ — $ — $ 409,616 Nonrecurring fair value measurements: Assets: Impaired assets (2) $ — $ — $ 67,815 $ 67,815 $ 27,225 (1) Represents impairment loss of $27.2 million recognized during the second quarter of 2018 related to a jack-up (2) Represents the total book value as of June 30, 2018 of a jack-up December 31, 2017 Fair Value Measurements Using Level 1 Level 2 Level 3 Assets at Total for Year (1) Recurring fair value measurements: Assets: Short-term investments $ 358,019 $ — $ — $ 358,019 Nonrecurring fair value measurements: Assets: Impaired assets (2) $ — $ — $ 97,261 $ 97,261 $ 99,313 (1) Represents impairment losses of $71.3 million and $28.0 million recognized during the second and fourth quarters of 2017, respectively, related to three drilling rigs whose carrying values were impaired. See Note 3. (2) Represents the total book value as of December 31, 2017 of two floaters, which were written down to their estimated fair values during the second quarter of 2017, and one jack-up
Fair Values and Related Carrying Values of Our Debt Instruments	June 30, 2018 December 31, 2017 Fair Value Carrying Value Fair Value Carrying Value 3.45% Senior Notes due 2023 $ 221.9 $ 249.4 $ 223.1 $ 249.4 7.875% Senior Notes due 2025 518.1 496.6 523.1 496.5 5.70% Senior Notes due 2039 400.0 497.2 405.0 497.2 4.875% Senior Notes due 2043 540.0 748.9 547.5 748.9

Drilling and Other Property a26

Drilling and Other Property and Equipment (Tables)	6 Months Ended
	Jun. 30, 2018
Property, Plant and Equipment [Abstract]
Summary of Cost and Accumulated Depreciation of Drilling and Other Property and Equipment	Cost and accumulated depreciation of drilling and other property and equipment are summarized as follows (in thousands): June 30, December 31, 2018 2017 Drilling rigs and equipment $ 8,064,663 $ 7,971,406 Land and buildings 63,554 63,309 Office equipment and other 87,702 82,691 Cost 8,215,919 8,117,406 Less: accumulated depreciation (3,018,722 ) (2,855,765 ) Drilling and other property and equipment, net $ 5,197,197 $ 5,261,641

Segments and Geographic Area 27

Segments and Geographic Area Analysis (Tables)	6 Months Ended
	Jun. 30, 2018
Segment Reporting [Abstract]
Summary of Information about Disaggregated Revenue by Equipment-type and Primary Geographical Market	The following tables provide information about disaggregated revenue by equipment-type and primary geographical market (in thousands): Three Months Ended June 30, 2018 Floater Jack-up (1) Total Revenues Total United States $ 158,554 $ 3,648 $ 162,202 $ 1,172 $ 163,374 South America 26,288 — 26,288 — 26,288 Europe 18,738 — 18,738 1,742 20,480 Australia/Asia 58,125 — 58,125 594 58,719 Total $ 261,705 $ 3,648 $ 265,353 $ 3,508 $ 268,861 (1) Loss-of-hire jack-up Six Months Ended June 30, 2018 Floater Jack-up (1) Total Revenues Total United States $ 318,228 $ 8,413 $ 326,641 $ 3,309 $ 329,950 South America 80,556 — 80,556 1 80,557 Europe 30,130 — 30,130 3,120 33,250 Australia/Asia 115,952 — 115,952 4,662 120,614 Total $ 544,866 $ 8,413 $ 553,279 $ 11,092 $ 564,371 (1) Loss-of-hire jack-up Three Months Ended June 30, 2017 Floater Jack-up Total Revenues Total United States $ 157,069 $ — $ 157,069 $ 2,335 $ 159,404 South America 111,498 — 111,498 (240 ) 111,258 Europe 44,533 — 44,533 1,194 45,727 Australia/Asia 72,883 — 72,883 3,593 76,476 Mexico — 6,187 6,187 237 6,424 Total $ 385,983 $ 6,187 $ 392,170 $ 7,119 $ 399,289 Six Months Ended June 30, 2017 Floater Jack-up Total Revenues Total United States $ 292,668 $ — $ 292,668 $ 4,456 $ 297,124 South America 214,179 — 214,179 (222 ) 213,957 Europe 100,268 — 100,268 3,159 103,427 Australia/Asia 138,561 — 138,561 10,009 148,570 Mexico — 10,051 10,051 386 10,437 Total $ 745,676 $ 10,051 $ 755,727 $ 17,788 $ 773,515

General Information - Additiona

General Information - Additional Information (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jul. 27, 2018
Property, Plant and Equipment [Line Items]
Future minimum lease commitments	$ 490
ASU 2016-16 [Member]
Property, Plant and Equipment [Line Items]
Reduction in retained earnings	$ 17.4
Subsequent Event [Member]
Property, Plant and Equipment [Line Items]
Outstanding common stock owned by Loews Corporation		53.00%

General Information - Summary o

General Information - Summary of Aggregate Impact of Changes in Accounting Principles (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings	$ 1,899,735	$ 1,949,686	$ 1,964,497
Prepaid expenses and other current assets	154,408	158,236	157,625
Other assets	71,389	104,383	102,276
Deferred tax liability	$ 124,350	184,828	$ 167,299
Previously Reported [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings		1,964,497
Prepaid expenses and other current assets		157,625
Other assets		102,276
Deferred tax liability		167,299
Restatement Adjustment [Member] | Accounting Standards Update 2014-09 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings		2,590
Prepaid expenses and other current assets		611
Other assets		2,107
Deferred tax liability		128
Restatement Adjustment [Member] | ASU 2016-16 [Member]
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Retained earnings		(17,401)
Deferred tax liability		$ 17,401

Revenue from Contracts with C30

Revenue from Contracts with Customers - Additional Information (Detail) - USD ($)	3 Months Ended	6 Months Ended	12 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2017
Revenue from Contract with Customers [Line Items]
Payment terms on invoiced amounts		30 days
Deferred contract costs	$ 56,110,000	$ 56,110,000	$ 56,110,000	$ 51,297,000
Contract costs amortization	14,300,000	27,200,000
Contract costs impairment loss	0	0
Prepaid Expenses and Other Current Assets [Member]
Revenue from Contract with Customers [Line Items]
Deferred contract costs	56,100,000	56,100,000	56,100,000
Other Assets [Member]
Revenue from Contract with Customers [Line Items]
Deferred contract costs	$ 25,100,000	$ 25,100,000	$ 25,100,000
Minimum [Member]
Revenue from Contract with Customers [Line Items]
Initial term of contract			2 months
Maximum [Member]
Revenue from Contract with Customers [Line Items]
Initial term of contract			60 months

Revenue from Contracts with C31

Revenue from Contracts with Customers - Summary of Information about Receivables, Contract Assets and Contract Liabilities from Contracts with Customers (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Revenue from Contract with Customer [Abstract]
Trade receivables	$ 194,425	$ 247,453	$ 247,453
Current contract assets	1,567	611
Noncurrent contract assets	2,107	2,107
Current contract liabilities (deferred revenue)	(10,173)	(11,371)	$ (11,371)
Noncurrent contract liabilities (deferred revenue)	$ (6,915)	$ (8,972)

Revenue from Contracts with C32

Revenue from Contracts with Customers - Summary of Significant Changes in Contract Assets and Contract Liabilities Balances (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2018USD ($)
Revenue from Contract with Customer [Abstract]
Contract assets at January 1, 2018	$ 2,718
Contract liabilities at January 1, 2018	(20,343)
Net balance at January 1, 2018	(17,625)
Decrease due to amortization of revenue that was included in the beginning contract liability balance	7,048
Increase due to cash received, excluding amounts recognized as revenue during the period	(4,670)
Increase due to revenue recognized during the period but contingent on future performance	2,306
Decrease due to transfer to receivables during the period	(611)
Adjustments	138
Net balance at June 30, 2018	(13,414)
Contract assets at June 30, 2018	3,674
Contract liabilities at June 30, 2018	$ (17,088)

Revenue from Contracts with C33

Revenue from Contracts with Customers - Summary of Revenue Expected to be Recognized in Future Related to Unsatisfied Performance Obligations (Detail) $ in Thousands	Jun. 30, 2018USD ($)
Revenue from Contract with Customers [Line Items]
Revenue remaining performance obligation	$ 38,463
Mobilization and Contract Preparation Revenue [Member]
Revenue from Contract with Customers [Line Items]
Revenue remaining performance obligation	18,239
Capital Modification Revenue [Member]
Revenue from Contract with Customers [Line Items]
Revenue remaining performance obligation	16,155
Demobilization Revenue [Member]
Revenue from Contract with Customers [Line Items]
Revenue remaining performance obligation	2,170
Other Deferred Revenue [Member]
Revenue from Contract with Customers [Line Items]
Revenue remaining performance obligation	1,899
2018 [Member]
Revenue from Contract with Customers [Line Items]
Revenue remaining performance obligation	18,226
2018 [Member] | Mobilization and Contract Preparation Revenue [Member]
Revenue from Contract with Customers [Line Items]
Revenue remaining performance obligation	9,115
2018 [Member] | Capital Modification Revenue [Member]
Revenue from Contract with Customers [Line Items]
Revenue remaining performance obligation	6,598
2018 [Member] | Demobilization Revenue [Member]
Revenue from Contract with Customers [Line Items]
Revenue remaining performance obligation	2,170
2018 [Member] | Other Deferred Revenue [Member]
Revenue from Contract with Customers [Line Items]
Revenue remaining performance obligation	343
2019 [Member]
Revenue from Contract with Customers [Line Items]
Revenue remaining performance obligation	18,894
2019 [Member] | Mobilization and Contract Preparation Revenue [Member]
Revenue from Contract with Customers [Line Items]
Revenue remaining performance obligation	9,043
2019 [Member] | Capital Modification Revenue [Member]
Revenue from Contract with Customers [Line Items]
Revenue remaining performance obligation	9,170
2019 [Member] | Other Deferred Revenue [Member]
Revenue from Contract with Customers [Line Items]
Revenue remaining performance obligation	681
2020 [Member]
Revenue from Contract with Customers [Line Items]
Revenue remaining performance obligation	1,149
2020 [Member] | Mobilization and Contract Preparation Revenue [Member]
Revenue from Contract with Customers [Line Items]
Revenue remaining performance obligation	81
2020 [Member] | Capital Modification Revenue [Member]
Revenue from Contract with Customers [Line Items]
Revenue remaining performance obligation	387
2020 [Member] | Other Deferred Revenue [Member]
Revenue from Contract with Customers [Line Items]
Revenue remaining performance obligation	681
2021 [Member]
Revenue from Contract with Customers [Line Items]
Revenue remaining performance obligation	194
2021 [Member] | Other Deferred Revenue [Member]
Revenue from Contract with Customers [Line Items]
Revenue remaining performance obligation	$ 194

Revenue from Contracts with C34

Revenue from Contracts with Customers - Summary of Comparison of Selected Unaudited Condensed Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Unaudited Condensed Consolidated Balance Sheets
Prepaid and other current assets	$ 154,408	$ 158,236	$ 157,625
Other assets	71,389	104,383	102,276
Accrued liabilities	130,123		154,655
Deferred tax liability	124,350	184,828	167,299
Retained earnings	1,899,735	$ 1,949,686	$ 1,964,497
Adjustments [Member] | Accounting Standards Update 2014-09 [Member]
Unaudited Condensed Consolidated Balance Sheets
Prepaid and other current assets	(1,174)
Other assets	(2,107)
Accrued liabilities	739
Deferred tax liability	(402)
Retained earnings	(3,619)
Balance Without Adoption of Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Unaudited Condensed Consolidated Balance Sheets
Prepaid and other current assets	153,234
Other assets	69,282
Accrued liabilities	130,862
Deferred tax liability	123,948
Retained earnings	$ 1,896,116

Revenue from Contracts with C35

Revenue from Contracts with Customers - Summary of Comparison of Selected Unaudited Condensed Statement of Operations and Cash Flows Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Unaudited Condensed Consolidated Statements of Operations
Total revenues	$ 268,861	$ 399,289	$ 564,371	$ 773,515
Income tax benefit	$ 10,012	$ 22,969	$ 54,475	$ 22,046
Loss per share, Basic and Diluted	$ (0.50)	$ 0.12	$ (0.36)	$ 0.29
Cash flow from operating activities:
Net loss	$ (69,274)	$ 15,949	$ (49,953)	$ 39,488
Adjustments to reconcile net loss to net cash
Deferred tax provision			(61,160)	(54,425)
Contract liabilities			(3,255)	11,524
Contract assets			(956)
Contract Drilling [Member]
Unaudited Condensed Consolidated Statements of Operations
Total revenues	$ 265,353	$ 392,170	553,279	$ 755,727
Adjustments [Member] | Accounting Standards Update 2014-09 [Member]
Unaudited Condensed Consolidated Statements of Operations
Income tax benefit			$ 274
Loss per share, Basic and Diluted			$ (0.01)
Cash flow from operating activities:
Net loss			$ (1,029)
Adjustments to reconcile net loss to net cash
Deferred tax provision			(274)
Contract liabilities			739
Contract assets			564
Adjustments [Member] | Accounting Standards Update 2014-09 [Member] | Contract Drilling [Member]
Unaudited Condensed Consolidated Statements of Operations
Total revenues			(1,303)
Balance Without Adoption of Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Unaudited Condensed Consolidated Statements of Operations
Income tax benefit			$ 54,749
Loss per share, Basic and Diluted			$ (0.37)
Cash flow from operating activities:
Net loss			$ (50,982)
Adjustments to reconcile net loss to net cash
Deferred tax provision			(61,434)
Contract liabilities			(2,516)
Contract assets			(392)
Balance Without Adoption of Topic 606 [Member] | Accounting Standards Update 2014-09 [Member] | Contract Drilling [Member]
Unaudited Condensed Consolidated Statements of Operations
Total revenues			$ 551,976

Impairment of Assets - Addition

Impairment of Assets - Additional Information (Detail)	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2018USD ($)Rigs	Dec. 31, 2017USD ($)Rigs	Jun. 30, 2017USD ($)Rigs	Jun. 30, 2018USD ($)Rigs	Jun. 30, 2017USD ($)	Dec. 31, 2017USD ($)Rigs
Schedule Of Asset Impairment Charges [Line Items]
Loss on impairment of assets | $	$ 27,225,000		$ 71,268,000	$ 27,225,000	$ 71,268,000	$ 99,300,000
Number of rigs not evaluated for impairment	9			9
2018 Impaired Rigs [Member]
Schedule Of Asset Impairment Charges [Line Items]
Number of rigs evaluated for impairment	4
Loss on impairment of assets | $	$ 27,200,000			$ 0
Impaired long-lived assets held and used, method for determining fair value				We estimated the fair value of the impaired jack-up rig using a market approach based on a signed agreement to sell the rig, including estimated costs to sell. We consider this valuation approach to be a Level 3 fair value measurement due to the level of estimation involved as the sale had not yet been completed at the time of our analysis. The Ocean Scepter was sold in July 2018.
2017 Impaired Rigs [Member]
Schedule Of Asset Impairment Charges [Line Items]
Number of rigs evaluated for impairment			7
Loss on impairment of assets | $		$ 28,000,000	$ 71,300,000
Impaired long-lived assets held and used, method for determining fair value				We estimated the fair value of the 2017 Impaired Rigs using an income approach, whereby the fair value of each rig was estimated based on a calculation of the rig’s future net cash flows. These calculations utilized significant unobservable inputs, including estimated proceeds that may be received on ultimate disposition of the rig, and are representative of Level 3 fair value measurements due to the significant level of estimation involved and lack of transparency as to the inputs used. During the second quarter of 2017, we recorded an impairment loss of $71.3 million related to our 2017 Impaired Rigs.
Number of rigs impaired		1	2			3
Ultra-deep Water Rigs [Member] | 2017 Impaired Rigs [Member]
Schedule Of Asset Impairment Charges [Line Items]
Number of rigs impaired			1
Deep Water Rigs [Member] | 2017 Impaired Rigs [Member]
Schedule Of Asset Impairment Charges [Line Items]
Number of rigs impaired			1

Supplemental Financial Inform37

Supplemental Financial Information - Accounts Receivable, Net of Allowance for Doubtful Accounts (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Receivables [Abstract]
Trade receivables	$ 194,425	$ 247,453	$ 247,453
Value added tax receivables	13,645		14,067
Related party receivables	113		205
Other	407		464
Receivables Gross Current, Total	208,590		262,189
Allowance for bad debts	(5,459)		(5,459)
Total	$ 203,131		$ 256,730

Supplemental Financial Inform38

Supplemental Financial Information - Prepaid Expenses and Other Current Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Rig spare parts and supplies	$ 23,887		$ 28,383
Deferred contract costs	56,110		51,297
Prepaid BOP lease	3,873		3,873
Prepaid insurance	4,407		3,091
Prepaid taxes	58,417		67,212
Other	7,714		3,769
Total	$ 154,408	$ 158,236	$ 157,625

Supplemental Financial Inform39

Supplemental Financial Information - Accrued Liabilities (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Jan. 01, 2018	Dec. 31, 2017
Payables and Accruals [Abstract]
Rig operating expenses	$ 30,055		$ 48,894
Payroll and benefits	32,929		46,560
Deferred revenue	10,173	$ 11,371	11,371
Accrued capital project/upgrade costs	12,714		3,698
Interest payable	28,234		28,234
Personal injury and other claims	6,048		5,699
Other	9,970		10,199
Total	$ 130,123		$ 154,655

Supplemental Financial Inform40

Supplemental Financial Information - Additional Information (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Supplemental Cash Flow Information [Abstract]
Accrued costs related to restructuring plan	$ 2.2	$ 13.6

Supplemental Financial Inform41

Supplemental Financial Information - Noncash Investing and Financing Activities (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Condensed Financial Statements, Captions [Line Items]
Accrued but unpaid capital expenditures at period end	$ 12,714	$ 3,649
Common stock withheld for payroll tax obligations	1,265	473
Cash interest payments	56,531	51,603
Foreign [Member]
Cash income taxes paid, net of (refunds):
Cash income taxes paid, net of refunds	4,035	33,319
State [Member]
Cash income taxes paid, net of (refunds):
Cash income taxes paid, net of refunds	$ 2	$ 94

Supplemental Financial Inform42

Supplemental Financial Information - Noncash Investing and Financing Activities (Parenthetical) (Detail) - shares	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Restricted Stock [Member]
Condensed Financial Statements, Captions [Line Items]
Number of shares of common stock withheld	85,580	28,386

Earnings Per Share - Reconcilia

Earnings Per Share - Reconciliation of Numerators and Denominators of Basic and Diluted Per-Share Computations (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Earnings Per Share [Abstract]
Net (loss) income - basic and diluted numerator	$ (69,274)	$ 15,949	$ (49,953)	$ 39,488
Weighted average shares - basic (denominator):	137,429	137,224	137,362	137,199
Dilutive effect of stock-based awards		3		36
Weighted average shares including conversions - diluted (denominator)	137,429	137,227	137,362	137,235
(Loss) earnings per share:
Basic	$ (0.50)	$ 0.12	$ (0.36)	$ 0.29
Diluted	$ (0.50)	$ 0.12	$ (0.36)	$ 0.29

Earnings Per Share - Securities

Earnings Per Share - Securities Excluded from Computations of Diluted Earnings Per Share (Detail) - shares shares in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Stock Options [Member]
Employee and director:
Securities excluded from computation of diluted earning per share				1
Restricted Stock Units [Member]
Employee and director:
Securities excluded from computation of diluted earning per share	1,194	1,274	1,133	933
Stock Appreciation Rights [Member]
Employee and director:
Securities excluded from computation of diluted earning per share	1,144	1,301	1,207	1,355

Marketable Securities - Schedul

Marketable Securities - Schedule of Marketable Securities (Detail) $ in Thousands	6 Months Ended
	Jun. 30, 2018USD ($)
Marketable Securities [Line Items]
Market Value	$ 274,671
U.S. Treasury Bills (due within one year) [Member]
Marketable Securities [Line Items]
Amortized Cost	274,636
Unrealized Gain	35
Market Value	$ 274,671

Marketable Securities - Additio

Marketable Securities - Additional Information (Detail) - USD ($)	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018
Marketable Securities [Line Items]
Proceeds from sale and maturities of marketable securities		$ 300,000,000
U.S. Treasury Bills (due within one year) [Member]
Marketable Securities [Line Items]
Proceeds from sale and maturities of marketable securities	$ 300,000,000	300,000,000
Proceeds from sales	$ 0	$ 0

Financial Instruments and Fai47

Financial Instruments and Fair Value Disclosures - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Transfers between fair value levels			$ 0		$ 0
Impairment charges	$ 27,225,000	$ 71,268,000	$ 27,225,000	$ 71,268,000	99,300,000
Measurement period for determining fair value of debt instruments			10 days
Level 1 [Member] | Cash Held in Money Market Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of investments	114,000,000		$ 114,000,000		337,100,000
Level 1 [Member] | Time Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of investments	20,900,000		20,900,000		$ 20,900,000
Level 1 [Member] | US Treasury Bill [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value of investments	$ 274,700,000		$ 274,700,000

Financial Instruments and Fai48

Financial Instruments and Fair Value Disclosures - Assets and Liabilities Measured at Fair Value on Recurring and Nonrecurring Basis (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Assets:
Loss on assets	$ 27,225	$ 71,268	$ 27,225	$ 71,268	$ 99,300
Carrying value of impaired assets					1,000
Fair Value Measurements, Recurring [Member]
Assets:
Short-term investments	409,616		409,616		358,019
Fair Value Measurements, Recurring [Member] | Level 1 [Member]
Assets:
Short-term investments	409,616		409,616		358,019
Nonrecurring Fair Value Measurements [Member]
Assets:
Loss on assets			27,225		99,313
Carrying value of impaired assets	67,815		67,815		97,261
Nonrecurring Fair Value Measurements [Member] | Level 3 [Member]
Assets:
Carrying value of impaired assets	$ 67,815		$ 67,815		$ 97,261

Financial Instruments and Fai49

Financial Instruments and Fair Value Disclosures - Assets and Liabilities Measured at Fair Value on Recurring and Nonrecurring Basis (Parenthetical) (Detail)	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2018USD ($)	Dec. 31, 2017USD ($)Rigs	Jun. 30, 2017USD ($)Rigs	Jun. 30, 2018USD ($)	Jun. 30, 2017USD ($)	Dec. 31, 2017USD ($)Rigs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment of assets	$ 27,225,000		$ 71,268,000	$ 27,225,000	$ 71,268,000	$ 99,300,000
Carrying value of impaired assets		$ 1,000,000				1,000,000
Held for Sale [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value of impaired assets		96,300,000				$ 96,300,000
2017 Impaired Rigs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment of assets		$ 28,000,000	$ 71,300,000
Number of rigs written down to their estimated fair value | Rigs		1	2			3
2018 Impaired Rigs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment of assets	27,200,000			0
Nonrecurring Fair Value Measurements [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loss on impairment of assets				27,225,000		$ 99,313,000
Carrying value of impaired assets	$ 67,815,000	$ 97,261,000		$ 67,815,000		$ 97,261,000
Nonrecurring Fair Value Measurements [Member] | Floater Rigs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of rigs written down to their estimated fair value | Rigs						2
Nonrecurring Fair Value Measurements [Member] | Jack-up Rigs [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Number of rigs written down to their estimated fair value | Rigs						1

Financial Instruments and Fai50

Financial Instruments and Fair Value Disclosures - Fair Value and Related Carrying Values of Our Debt Instruments (Detail) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
3.45% Senior Notes due 2023 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	$ 221.9	$ 223.1
Carrying Value	249.4	249.4
7.875% Senior Notes due 2025 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	518.1	523.1
Carrying Value	496.6	496.5
5.70% Senior Notes due 2039 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	400	405
Carrying Value	497.2	497.2
4.875% Senior Notes due 2043 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	540	547.5
Carrying Value	$ 748.9	$ 748.9

Financial Instruments and Fai51

Financial Instruments and Fair Value Disclosures - Fair Value and Related Carrying Values of Our Debt Instruments (Parenthetical) (Detail)	Jun. 30, 2018	Dec. 31, 2017
3.45% Senior Notes due 2023 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate of senior notes	3.45%	3.45%
7.875% Senior Notes due 2025 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate of senior notes	7.875%	7.875%
5.70% Senior Notes due 2039 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate of senior notes	5.70%	5.70%
4.875% Senior Notes due 2043 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate of senior notes	4.875%	4.875%

Drilling and Other Property a52

Drilling and Other Property and Equipment - Summary of Cost and Accumulated Depreciation of Drilling and Other Property and Equipment (Detail) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property and equipment	$ 8,215,919	$ 8,117,406
Less: accumulated depreciation	(3,018,722)	(2,855,765)
Drilling and other property and equipment, net	5,197,197	5,261,641
Drilling Rigs and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	8,064,663	7,971,406
Land and Buildings [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	63,554	63,309
Office Equipment and Other [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	$ 87,702	$ 82,691

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail) - USD ($)	6 Months Ended
	Jun. 30, 2018	Dec. 31, 2017
Contingencies And Commitments [Line Items]
Deductible for marine liability coverage including personal injury claims, per first occurrence	$ 10,000,000
Range of deductible for liability coverage for personal injury claims, lower limit	5,000,000
Range of deductible for liability coverage for personal injury claims, upper limit	100,000,000
Total Contingent Liabilities Under Letters of Credit and Bonds [Member]
Contingencies And Commitments [Line Items]
Contingent liability under letters of credit and other bonds	11,200,000
Potentially Collateralized Contingent Liability Under Letters Of Credit and Bonds [Member]
Contingencies And Commitments [Line Items]
Contingent liability under letters of credit and other bonds	5,500,000
Windstorms in U.S. Gulf of Mexico [Member]
Contingencies And Commitments [Line Items]
Deductible for marine liability coverage including personal injury claims, per first occurrence	25,000,000
Range of deductible for liability coverage for personal injury claims, lower limit	25,000,000
Range of deductible for liability coverage for personal injury claims, upper limit	100,000,000
Personal Injury Claims [Member]
Contingencies And Commitments [Line Items]
Personal injury claims recorded	29,000,000	$ 30,900,000
Personal Injury Claims [Member] | Accrued Liabilities [Member]
Contingencies And Commitments [Line Items]
Personal injury claims recorded	5,300,000	5,200,000
Personal Injury Claims [Member] | Other Liabilities [Member]
Contingencies And Commitments [Line Items]
Personal injury claims recorded	$ 23,700,000	$ 25,700,000

Restructuring and Separation 54

Restructuring and Separation Costs - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restructuring Cost and Reserve [Line Items]
Accrued costs associated with Corporate Reduction Plan	$ 2.2	$ 2.2			$ 13.6
2017 Reduction Plan [Member] | Severance Payments [Member]
Restructuring Cost and Reserve [Line Items]
Accrued costs associated with Corporate Reduction Plan	2.2	2.2		$ 0.7
2017 Reduction Plan [Member] | Severance Payments [Member] | Scenario, Forecast [Member]
Restructuring Cost and Reserve [Line Items]
Accrued costs associated with Corporate Reduction Plan			$ 1.5
2017 Reduction Plan [Member] | Redundant Employees [Member]
Restructuring Cost and Reserve [Line Items]
Costs associated with Corporate Reduction Plan	$ 1.3	$ 4.3
Restructuring a cost description		As of June 30, 2018, accrued costs related to severance payments to former employees were $2.2 million, of which $0.7 million is payable during the remainder of 2018 and $1.5 million is payable in 2019.

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Dec. 31, 2017	Jun. 30, 2018
Income Tax Contingency [Line Items]
Net tax expense related to tax law change	$ 1.1
Reversal of liability for an uncertain tax position		$ 43.3
U.S corporate income tax rate	35.00%	21.00%
ASU 2016-16 [Member]
Income Tax Contingency [Line Items]
Cumulative effect of applying new standard as adjustment to opening retained earnings		$ 17.4

Segments and Geographic Area 56

Segments and Geographic Area Analysis - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2018CountrySegment
Segment Reporting [Abstract]
Number of reportable segments | Segment	1
Number of countries with rigs | Country	4

Segments and Geographic Area 57

Segments and Geographic Area Analysis - Summary of Information about Disaggregated Revenue by Equipment-type and Primary Geographical Market (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Segment Reporting Information [Line Items]
Total revenues	$ 268,861	$ 399,289	$ 564,371	$ 773,515
Contract Drilling [Member]
Segment Reporting Information [Line Items]
Total revenues	265,353	392,170	553,279	755,727
Reimbursable Expenses [Member]
Segment Reporting Information [Line Items]
Total revenues	3,508	7,119	11,092	17,788
United States [Member]
Segment Reporting Information [Line Items]
Total revenues	163,374	159,404	329,950	297,124
United States [Member] | Contract Drilling [Member]
Segment Reporting Information [Line Items]
Total revenues	162,202	157,069	326,641	292,668
United States [Member] | Reimbursable Expenses [Member]
Segment Reporting Information [Line Items]
Total revenues	1,172	2,335	3,309	4,456
South America [Member]
Segment Reporting Information [Line Items]
Total revenues	26,288	111,258	80,557	213,957
South America [Member] | Contract Drilling [Member]
Segment Reporting Information [Line Items]
Total revenues	26,288	111,498	80,556	214,179
South America [Member] | Reimbursable Expenses [Member]
Segment Reporting Information [Line Items]
Total revenues		(240)	1	(222)
Europe [Member]
Segment Reporting Information [Line Items]
Total revenues	20,480	45,727	33,250	103,427
Europe [Member] | Contract Drilling [Member]
Segment Reporting Information [Line Items]
Total revenues	18,738	44,533	30,130	100,268
Europe [Member] | Reimbursable Expenses [Member]
Segment Reporting Information [Line Items]
Total revenues	1,742	1,194	3,120	3,159
Australia/Asia [Member]
Segment Reporting Information [Line Items]
Total revenues	58,719	76,476	120,614	148,570
Australia/Asia [Member] | Contract Drilling [Member]
Segment Reporting Information [Line Items]
Total revenues	58,125	72,883	115,952	138,561
Australia/Asia [Member] | Reimbursable Expenses [Member]
Segment Reporting Information [Line Items]
Total revenues	594	3,593	4,662	10,009
Mexico [Member]
Segment Reporting Information [Line Items]
Total revenues		6,424		10,437
Mexico [Member] | Contract Drilling [Member]
Segment Reporting Information [Line Items]
Total revenues		6,187		10,051
Mexico [Member] | Reimbursable Expenses [Member]
Segment Reporting Information [Line Items]
Total revenues		237		386
Floater Rigs [Member] | Contract Drilling [Member]
Segment Reporting Information [Line Items]
Total revenues	261,705	385,983	544,866	745,676
Floater Rigs [Member] | United States [Member] | Contract Drilling [Member]
Segment Reporting Information [Line Items]
Total revenues	158,554	157,069	318,228	292,668
Floater Rigs [Member] | South America [Member] | Contract Drilling [Member]
Segment Reporting Information [Line Items]
Total revenues	26,288	111,498	80,556	214,179
Floater Rigs [Member] | Europe [Member] | Contract Drilling [Member]
Segment Reporting Information [Line Items]
Total revenues	18,738	44,533	30,130	100,268
Floater Rigs [Member] | Australia/Asia [Member] | Contract Drilling [Member]
Segment Reporting Information [Line Items]
Total revenues	58,125	72,883	115,952	138,561
Jack-up Rigs [Member] | Contract Drilling [Member]
Segment Reporting Information [Line Items]
Total revenues	3,648	6,187	8,413	10,051
Jack-up Rigs [Member] | United States [Member] | Contract Drilling [Member]
Segment Reporting Information [Line Items]
Total revenues	$ 3,648		$ 8,413
Jack-up Rigs [Member] | Mexico [Member] | Contract Drilling [Member]
Segment Reporting Information [Line Items]
Total revenues		$ 6,187		$ 10,051