Diamond Offshore Drilling (DODRW) 10-Q 30 Oct 13 2013 Q3 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	9 Months Ended
	Sep. 30, 2013	Oct. 25, 2013
Document And Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	FALSE
Document Period End Date	30-Sep-13
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q3
Trading Symbol	DO
Entity Registrant Name	DIAMOND OFFSHORE DRILLING INC
Entity Central Index Key	949039
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		139,035,448

Consolidated_Balance_Sheets

Consolidated Balance Sheets (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Current assets:
Cash and cash equivalents	$438,794	$335,432
Marketable securities	800,204	1,150,158
Accounts receivable, net of allowance for bad debts	424,808	499,660
Prepaid expenses and other current assets	142,152	136,099
Assets held for sale	11,594	11,594
Total current assets	1,817,552	2,132,943
Drilling and other property and equipment, net of accumulated depreciation	5,331,470	4,864,972
Other assets	193,586	237,371
Total assets	7,342,608	7,235,286
Current liabilities:
Accounts payable	86,533	96,631
Accrued liabilities	354,232	324,434
Taxes payable	26,175	64,481
Current portion of long-term debt	249,935
Total current liabilities	716,875	485,546
Long-term debt	1,246,321	1,496,066
Deferred tax liability	532,729	490,946
Other liabilities	182,347	186,334
Total liabilities	2,678,272	2,658,892
Commitments and contingencies (Note 8)
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; 143,952,248 shares issued and 139,035,448 shares outstanding at September 30, 2013; 143,948,370 shares issued and 139,031,570 shares outstanding at December 31, 2012)	1,440	1,439
Additional paid-in capital	1,986,693	1,983,957
Retained earnings	2,791,242	2,702,915
Accumulated other comprehensive gain (loss)	-626	2,496
Treasury stock, at cost (4,916,800 shares of common stock at September 30, 2013 and December 31, 2012)	-114,413	-114,413
Total stockholders' equity	4,664,336	4,576,394
Total liabilities and stockholders' equity	$7,342,608	$7,235,286

Consolidated_Balance_Sheets_Pa

Consolidated Balance Sheets (Parenthetical) (USD $)	Sep. 30, 2013	Dec. 31, 2012
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	143,952,248	143,948,370
Common stock, shares outstanding	139,035,448	139,031,570
Treasury stock, shares	4,916,800	4,916,800

Consolidated_Statements_of_Ope

Consolidated Statements of Operations (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues:
Contract drilling	$690,741	$714,027	$2,135,612	$2,195,443
Revenues related to reimbursable expenses	15,424	15,114	58,312	40,528
Total revenues	706,165	729,141	2,193,924	2,235,971
Operating expenses:
Contract drilling, excluding depreciation	419,488	357,281	1,163,618	1,159,635
Reimbursable expenses	14,904	14,563	56,998	39,351
Depreciation	97,143	99,207	291,107	300,069
General and administrative	15,240	13,476	48,490	49,803
Bad debt expense (recovery)	22,563		22,563	-1,018
Gain on disposition of assets	-525	-208	-2,789	-79,285
Total operating expenses	568,813	484,319	1,579,987	1,468,555
Operating income	137,352	244,822	613,937	767,416
Other income (expense):
Interest income	136	773	1,024	4,052
Interest expense	-1,693	-8,720	-17,713	-36,780
Foreign currency transaction loss	-4,556	-1,860	-3,949	-881
Other, net	326	-168	746	-767
Income before income tax expense	131,565	234,847	594,045	733,040
Income tax expense	-36,817	-56,661	-137,974	-168,224
Net income	$94,748	$178,186	$456,071	$564,816
Income per share:
Basic	$0.68	$1.28	$3.28	$4.06
Diluted	$0.68	$1.28	$3.28	$4.06
Weighted-average shares outstanding:
Shares of common stock	139,035	139,030	139,034	139,029
Dilutive potential shares of common stock	30	23	38	17
Total weighted-average shares outstanding	139,065	139,053	139,072	139,046
Cash dividends declared per share of common stock	$0.88	$0.88	$2.63	$2.63

Consolidated_Statements_of_Com

Consolidated Statements of Comprehensive Income (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Statement Of Income And Comprehensive Income [Abstract]
Net income	$94,748	$178,186	$456,071	$564,816
Foreign currency forward exchange contracts:
Unrealized holding gain (loss)	1,615	1,118	-4,901	4,024
Reclassification adjustment for loss included in net income	3,622	1,868	1,918	3,445
Investments in marketable securities:
Unrealized holding (loss) gain	-2	29	7	18
Reclassification adjustment for loss (gain) included in net income	-14	-28	-146	56
Total other comprehensive gain (loss)	5,221	2,987	-3,122	7,543
Comprehensive income	$99,969	$181,173	$452,949	$572,359

Consolidated_Statements_of_Cas

Consolidated Statements of Cash Flows (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Operating activities:
Net income	$456,071	$564,816
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	291,107	300,069
Gain on disposition of assets	-2,789	-79,285
Loss on foreign currency forward exchange contracts	2,246	5,692
Deferred tax provision	43,414	-6,089
Accretion of discounts on marketable securities	-584	4,461
Stock-based compensation expense	2,627	3,248
Deferred income, net	-45,600	-19,020
Deferred expenses, net	20,441	58,391
Long-term employee remuneration programs	6,617	4,572
Other assets, noncurrent	-4,487	2,697
Other liabilities, noncurrent	-51	2,457
Proceeds from (payments of) settlement of foreign currency forward exchange contracts designated as accounting hedges	-2,246	-5,692
Other	1,418	800
Changes in operating assets and liabilities:
Accounts receivable	74,965	108,159
Prepaid expenses and other current assets	-327	-9,350
Accounts payable and accrued liabilities	25,583	4,961
Taxes payable	-10,505	68,711
Net cash provided by operating activities	857,900	1,009,598
Investing activities:
Capital expenditures (including rig construction)	-740,460	-514,672
Proceeds from disposition of assets, net of disposal costs	3,357	136,937
Proceeds from sale and maturities of marketable securities	3,225,062	2,075,106
Purchases of marketable securities	-2,874,689	-2,352,635
Net cash used in investing activities	-386,730	-655,264
Financing activities:
Payment of dividends	-367,945	-367,984
Credit facility arrangement fees	-1	-3,646
Other	138	130
Net cash used in financing activities	-367,808	-371,500
Net change in cash and cash equivalents	103,362	-17,166
Cash and cash equivalents, beginning of period	335,432	333,765
Cash and cash equivalents, end of period	$438,794	$316,599

General_Information

General Information

9 Months Ended

Sep. 30, 2013

Accounting Policies [Abstract]

General Information

1. General Information

The unaudited 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 for the year ended December 31, 2012 (File No. 1-13926).

As of October 25, 2013, Loews Corporation owned 50.4% of the outstanding shares of our common stock.

Interim Financial Information

The accompanying unaudited 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 and Article 10 of Regulation S-X of the Securities and Exchange Commission. Accordingly, pursuant to such rules and regulations, they do not include all disclosures required by GAAP for complete financial statements. The consolidated financial information has not been audited but, in the opinion of management, includes all adjustments (consisting only of normal recurring accruals) necessary for a fair presentation of the consolidated balance sheets, statements of operations, statements of comprehensive income and statements of cash flows at the dates and for the periods indicated. Results of operations for interim periods are not necessarily indicative of results of operations for the respective full years.

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.

Reclassifications

Certain amounts applicable to the prior periods have been reclassified to conform to the classifications currently followed. Such reclassifications do not affect earnings.

Cash and Cash Equivalents

We consider short-term, highly liquid investments that have an original maturity of three months or less and deposits in money market mutual funds that are readily convertible into cash to be cash equivalents.

The effect of exchange rate changes on cash balances held in foreign currencies was not material for each of the three and nine-month periods ended September 30, 2013 and 2012.

Marketable Securities

We classify our investments in marketable securities as available for sale and they are stated at fair value in our Consolidated Balance Sheets. Accordingly, any unrealized gains and losses, net of taxes, are reported in our Consolidated Balance Sheets in “Accumulated other comprehensive gain (loss),” or AOCGL, until realized. The cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity and such adjustments are included in our Consolidated Statements of Operations in “Interest income.” The sale and purchase of securities are recorded on the date of the trade. The cost of debt securities sold is based on the specific identification method. Realized gains or losses, as well as any declines in value that are judged to be other than temporary, are reported in our Consolidated Statements of Operations in “Other income (expense) – Other, net.” See Note 4.

Provision for Bad Debts

We record a provision for bad debts on a case-by-case basis when facts and circumstances indicate that a customer receivable may not be collectible. In establishing these reserves, we consider historical and other factors that predict collectability, including write-offs, recoveries and the monitoring of credit quality. Such provision is reported as a component of “Operating expenses” in our Consolidated Statements of Operations. See Note 2.

Derivative Financial Instruments

Our derivative financial instruments consist of foreign currency forward exchange, or FOREX, contracts which we may designate as cash flow hedges. In accordance with GAAP, each derivative contract is stated in the balance sheet at its fair value with gains and losses reflected in the income statement except that, to the extent the derivative qualifies for and is designated as an accounting hedge, the gains and losses are reflected in income in the same period as offsetting gains and losses on the qualifying hedged positions. Designated hedges are expected to be highly effective, and therefore, adjustments to record the carrying value of the effective portion of our derivative financial instruments to their fair value are recorded as a component of AOCGL in our Consolidated Balance Sheets. The effective portion of the cash flow hedge will remain in AOCGL until it is reclassified into earnings in the period or periods during which the hedged transaction affects earnings or it is determined that the hedged transaction will not occur. We report such realized gains and losses as a component of “Contract drilling, excluding depreciation” expense in our Consolidated Statements of Operations to offset the impact of foreign currency fluctuations in our expenditures in local foreign currencies in the countries in which we operate. See Note 9.

Adjustments to record the carrying value of the ineffective portion of our derivative financial instruments to fair value and realized gains or losses upon settlement of derivative contracts not designated as cash flow hedges are reported as “Foreign currency transaction gain (loss)” in our Consolidated Statements of Operations. See Notes 5 and 6.

Assets Held For Sale

In 2012, our management adopted a plan to actively market for sale three cold-stacked mid-water semisubmersibles (the Ocean Epoch, the Ocean New Era and the Ocean Whittington) and one cold-stacked jack-up rig (the Ocean Spartan). In connection with the reclassification of these rigs to “Assets held for sale,” we measured the fair value of each rig in the disposal group using a probability-weighted cash flow analysis that utilized significant unobservable inputs, representing a Level 3 fair value measurement, which included assumptions for estimated proceeds that may be received upon disposition of the rig and estimated costs to sell. For our three mid-water semisubmersibles in the disposal group, we determined that, due to the expected resale market for rigs of this type and age, the highest and best use of these rigs would be for sale as scrap. Based on our analyses, we determined that the carrying values of the mid-water semisubmersible rigs in the disposal group were impaired, as the carrying value for each exceeded its aggregate fair value, and recognized an impairment loss in the fourth quarter of 2012. We determined that the carrying value of the Ocean Spartan was not impaired. At both September 30, 2013 and December 31, 2012, we reported “Assets held for sale” aggregating $11.6 million in our Consolidated Balance Sheets. See Note 6.

Drilling and Other Property and Equipment

We carry our drilling and other property and equipment at cost. Maintenance and routine repairs are charged to income currently while replacements and betterments, which upgrade or increase the functionality of our existing equipment and that significantly extend the useful life of an existing asset, are capitalized. Significant judgments, assumptions and estimates may be required in determining whether or not such replacements and betterments meet the criteria for capitalization and in determining useful lives and salvage values of such assets. Changes in these judgments, assumptions and estimates could produce results that differ from those reported. Historically, the amount of capital additions requiring significant judgments, assumptions or estimates has not been significant. During the nine months ended September 30, 2013 and the year ended December 31, 2012, we capitalized $189.2 million and $220.3 million, respectively, in replacements and betterments of our drilling fleet, resulting from numerous projects ranging from $25,000 to $60 million per project.

Costs incurred for major rig upgrades and/or the construction of rigs are accumulated in construction work-in-progress, with no depreciation recorded on the additions, until the month the upgrade or newbuild is completed and the rig is placed in service. Upon retirement or sale of a rig, the cost and related accumulated depreciation are removed from the respective accounts and any gains or losses are included in our results of operations as “Gain on disposition of assets.” Depreciation is recognized up to applicable salvage values by applying the straight-line method over the remaining estimated useful lives from the year the asset is placed in service. Drilling rigs and equipment are depreciated over their estimated useful lives ranging from three to 30 years.

Capitalized Interest

We capitalize interest cost for qualifying construction and upgrade projects. See Note 7. A reconciliation of our total interest cost to “Interest expense” as reported in our Consolidated Statements of Operations is as follows:

Three Months Ended

Nine Months Ended

September 30,

September 30,

2013

2012

2013

2012

(In thousands)

Total interest cost, including amortization of debt issuance costs

$

22,234

$

19,145

$

71,229

$

62,782

Capitalized interest

(20,541

)

(10,425

)

(53,516

)

(26,002

)

Total interest expense as reported

$

1,693

$

8,720

$

17,713

$

36,780

Impairment of Long-Lived Assets

We evaluate our property and equipment for impairment whenever changes in circumstances indicate that the carrying amount of an asset may not be recoverable, such as cold stacking a rig or excess spending over budget on a newbuild, construction project or major rig upgrade. There were no cold-stacked rigs at September 30, 2013 that were not being marketed for sale.

Current Portion of Long-Term Debt

Our 5.15% Senior Notes due September 1, 2014, or 5.15% Senior Notes, in the aggregate principal amount of $250.0 million will mature on September 1, 2014. Accordingly, the aggregate $249.9 million accreted value of our 5.15% Senior Notes has been presented as “Current portion of long-term debt” in our Consolidated Balance Sheets at September 30, 2013.

Foreign Currency

Our functional currency is the U.S. dollar. Foreign currency transaction gains and losses are reported as “Foreign currency transaction gain (loss)” in our Consolidated Statements of Operations and include, when applicable, unrealized gains and losses to record the carrying value of our FOREX contracts not designated as accounting hedges, as well as realized gains and losses from the settlement of such contracts. For the three-month and nine-month periods ended September 30, 2013, we recognized net foreign currency transaction (losses) of $(4.6) million and $(3.9) million, respectively. For the three-month and nine-month periods ended September 30, 2012, we recognized net foreign currency transaction (losses) of $(1.9) million and $(0.9) million, respectively. See Note 5.

Revenue Recognition

We recognize revenue from dayrate drilling contracts as services are performed. In connection with such drilling contracts, we may receive fees (either lump-sum or dayrate) for the mobilization of equipment. We earn these fees as services are performed over the initial term of the related drilling contracts. We defer mobilization fees received, as well as direct and incremental mobilization costs incurred, and amortize each, on a straight-line basis, over the term of the related drilling contracts (which is the period we estimate to be benefited from the mobilization activity). Straight-line amortization of mobilization revenues and related costs over the term of the related drilling contracts (which generally range from two to 60 months) is consistent with the timing of net cash flows generated from the actual drilling services performed. Absent a contract, mobilization costs are recognized currently.

Some of our drilling contracts require downtime before the start of the contract to prepare the rig to meet customer requirements. At times, we may be compensated by the customer for such work (either lump-sum or dayrate). These fees are generally earned as services are performed over the initial term of the related drilling contracts. We defer contract preparation fees received as well as direct and incremental costs associated with the contract preparation activities and amortize each, on a straight-line basis, over the term of the related drilling contracts (which we estimate to be benefited from the contract preparation activity).

From time to time, we may receive fees from our customers for capital improvements to our rigs (either lump-sum or dayrate). We defer such fees received in “Accrued liabilities” and “Other liabilities” in our Consolidated Balance Sheets and recognize these fees into income on a straight-line basis over the period of the related drilling contract. We capitalize the costs of such capital improvements and depreciate them over the estimated useful life of the improvement.

We record reimbursements received for the purchase of supplies, equipment, personnel services and other services provided at the request of our customers in accordance with a contract or agreement, for the gross amount billed to the customer, as “Revenues related to reimbursable expenses” in our Consolidated Statements of Operations.

Recent Accounting Pronouncements

In July 2013, the Financial Accounting Standards Board issued Accounting Standards Update 2013-11, or ASU 2013-11, which eliminates diversity in practice for the presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss or a tax credit carryforward is available to reduce the taxable income or tax payable that would result from disallowance of a tax position. ASU 2013-11 affects only the presentation of such amounts in an entity’s balance sheet and is effective for fiscal years beginning after December 15, 2013 and interim periods within those years. Early adoption is permitted. We are evaluating the impact, if any, of the adoption of ASU 2013-11 on our consolidated balance sheets.

Supplemental_Financial_Informa

Supplemental Financial Information	9 Months Ended
	Sep. 30, 2013
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Supplemental Financial Information	2. Supplemental Financial Information
	Consolidated Balance Sheets Information
	Accounts receivable, net of allowance for bad debts, consists of the following:
			September 30,			December 31,
			2013			2012
			(In thousands)
	Trade receivables		$	422,708		$	478,987
	Value added tax receivables			17,750			13,884
	Amounts held in escrow			12,025			11,555
	Related party receivables			353			527
	Other			124			165
				452,960			505,118
	Allowance for bad debts			(28,152	)		(5,458	)
	Total		$	424,808		$	499,660
	We recorded $22.6 million in bad debt expense during the three-month and nine-month periods ended September 30, 2013, to reserve the outstanding accounts receivable balance for two of our customers. See Note 6.
	Prepaid expenses and other current assets consist of the following:
			September 30,			December 31,
			2013			2012
			(In thousands)
	Rig spare parts and supplies		$	52,195		$	57,558
	Deferred mobilization costs			23,974			38,074
	Prepaid insurance			20,329			12,549
	Deferred tax assets			8,619			8,619
	Prepaid taxes			25,892			5,950
	FOREX contracts			3,272			3,627
	Other			7,871			9,722
	Total		$	142,152		$	136,099
	Accrued liabilities consist of the following:
			September 30,			December 31,
			2013			2012
			(In thousands)
	Rig operating expenses		$	87,069		$	70,078
	Payroll and benefits			107,210			88,612
	Deferred revenue			34,457			71,699
	Accrued capital project/upgrade costs			74,308			56,595
	Interest payable			29,422			21,219
	Personal injury and other claims			10,065			10,312
	FOREX contracts			4,304			29
	Other			7,397			5,890
	Total		$	354,232		$	324,434
	Consolidated Statements of Cash Flows Information
	Noncash investing activities excluded from the Consolidated Statements of Cash Flows and other supplemental cash flow information is as follows:
			Nine Months Ended
			September 30,
			2013			2012
			(In thousands)
	Accrued but unpaid capital expenditures at period end		$	74,308		$	48,620
	Cash interest payments(1)(2)			54,000			54,187
	Cash income taxes paid, net of refunds:
	U.S. federal			47,000			53,000
	Foreign			62,951			56,070
	State			190			212
	-1	Interest payments, net of amounts capitalized, were $8.9 million and $31.9 million for the nine months ended September 30, 2013 and 2012, respectively.
	-2	Interest paid on Internal Revenue Service assessments was $0.2 million during the nine months ended September 30, 2012.

Earnings_Per_Share

Earnings Per Share	9 Months Ended
	Sep. 30, 2013
Earnings Per Share [Abstract]
Earnings Per Share	3. Earnings Per Share
	A reconciliation of the numerators and the denominators of our basic and diluted per-share computations follows:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2013		2012		2013		2012
		(In thousands, except per share data)
	Net income – basic and diluted numerator:	$	94,748	$	178,186	$	456,071	$	564,816
	Weighted average shares – basic (denominator):		139,035		139,030		139,034		139,029
	Effect of dilutive potential shares
	Stock options and stock appreciation rights		30		23		38		17
	Weighted average shares including conversions – diluted (denominator)		139,065		139,053		139,072		139,046
	Earnings per share:
	Basic	$	0.68	$	1.28	$	3.28	$	4.06
	Diluted	$	0.68	$	1.28	$	3.28	$	4.06
	The following table sets forth the share effects of stock options and the number of stock appreciation rights excluded from our computations of diluted earnings per share, or EPS, as the inclusion of such potentially dilutive shares would have been antidilutive for the periods presented:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2013		2012		2013		2012
		(In thousands)
	Employee and director:
	Stock options		18		18		18		18
	Stock appreciation rights		982		874		885		900

Marketable_Securities

Marketable Securities	9 Months Ended
	Sep. 30, 2013
Investments Debt And Equity Securities [Abstract]
Marketable Securities	4. Marketable Securities
	We report our investments as current assets in our Consolidated Balance Sheets in “Marketable securities,” representing the investment of cash available for current operations. See Note 6.
	Our investments in marketable securities are classified as available for sale and are summarized as follows:
		September 30, 2013
		Amortized			Unrealized			Market
		Cost			Gain (Loss)			Value
		(In thousands)
	U.S. Treasury Bills and Notes (due within one year)	$	799,981		$	(1	)	$	799,980
	Mortgage-backed securities		212			12			224
	Total	$	800,193		$	11		$	800,204
		31-Dec-12
		Amortized			Unrealized			Market
		Cost			Gain (Loss)			Value
		(In thousands)
	U.S. Treasury Bills and Notes (due within one year)	$	1,149,707		$	150		$	1,149,857
	Mortgage-backed securities		276			25			301
	Total	$	1,149,983		$	175		$	1,150,158
	Proceeds from maturities and sales of marketable securities and gross realized gains and losses are summarized as follows:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2013			2012			2013			2012
		(In thousands)
	Proceeds from maturities	$	1,475,000		$	675,000		$	3,225,000		$	1,925,000
	Proceeds from sales		25			56			62			150,106
	Gross realized gains		—			—			—			—
	Gross realized losses		(1	)		(1	)		(1	)		(6	)

Derivative_Financial_Instrumen

Derivative Financial Instruments	9 Months Ended
	Sep. 30, 2013
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Derivative Financial Instruments	5. Derivative Financial Instruments
	Foreign Currency Forward Exchange Contracts
	Our international operations expose us to foreign exchange risk associated with our costs payable in foreign currencies for employee compensation, foreign income tax payments and purchases from foreign suppliers. We may utilize FOREX contracts to manage our foreign exchange risk. Our FOREX contracts generally require us to net settle the spread between the contracted foreign currency exchange rate and the spot rate on the contract settlement date, which, for most of our contracts, is the average spot rate for the contract period.
	We enter into FOREX contracts when we believe market conditions are favorable to purchase contracts for future settlement with the expectation that such contracts, when settled, will reduce our exposure to foreign currency gains and losses on future foreign currency expenditures. The amount and duration of such contracts are based on our monthly forecast of expenditures in the significant currencies in which we do business and for which there is a financial market (i.e., Australian dollars, Brazilian reais, British pounds sterling, Mexican pesos and Norwegian kroner). These forward contracts are derivatives as defined by GAAP.
	During the nine months ended September 30, 2013 and 2012, we settled FOREX contracts with aggregate notional values of approximately $233.9 million and $236.3 million, respectively, of which the entire aggregate amounts were designated as a cash flow accounting hedge. During the nine-month periods ended September 30, 2013 and 2012, we did not enter into or settle any FOREX contracts that were not designated as accounting hedges.
	The following table presents the aggregate amount of loss recognized in our Consolidated Statements of Operations related to our FOREX contracts designated as accounting hedges for the three-month and nine-month periods ended September 30, 2013 and 2012.
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
	Location of Loss Recognized in Income	2013			2012			2013				2012
		(In thousands)
	Contract drilling expense	$	(5,018	)	$	(2,715	)	$	(2,246	)		$	(5,692	)
	As of September 30, 2013, we had FOREX contracts outstanding in the aggregate notional amount of $151.6 million, consisting of $20.7 million in Australian dollars, $86.7 million in Brazilian reais, $20.5 million in British pounds sterling, $11.7 million in Mexican pesos and $12.0 million in Norwegian kroner. These contracts generally settle monthly through June 2014. As of September 30, 2013, all outstanding derivative contracts had been designated as cash flow hedges. See Note 6.
	We have International Swap Dealers Association, or ISDA, contracts, which are standardized master legal arrangements that establish key terms and conditions, which govern certain derivative transactions. At September 30, 2013, all of our FOREX contracts were with two counterparties and were governed under such ISDA contracts. There are no requirements to post collateral under these contracts; however, they do contain credit-risk related contingent provisions including credit support provisions and the net settlement of amounts owed in the event of early terminations. Additionally, should our credit rating fall below a specified rating immediately following the merger of the company with another entity, the counterparty may require all outstanding derivatives under the ISDA contract to be settled immediately at current market value. Our ISDA arrangements also include master netting agreements to further manage counterparty credit risk associated with our FOREX contracts. We have elected not to offset the fair value amounts recorded for our FOREX contracts under these agreements in our Consolidated Balance Sheets as of September 30, 2013 and December 31, 2012; however, there would have been no significant difference in our Consolidated Balance Sheets if the estimated fair values were presented on a net basis for these periods.
	The following table presents the fair values of our derivative FOREX contracts designated as hedging instruments at September 30, 2013 and December 31, 2012.
		Fair Value						Balance Sheet Location		Fair Value
	Balance Sheet Location	September 30,			December 31,					September 30,				December 31,
		2013			2012					2013				2012
		(In thousands)								(In thousands)
	Prepaid expenses and other current assets	$	3,272		$	3,627		Accrued liabilities		$	(4,304	)		$	(29	)
	The following table presents the amounts recognized in our Consolidated Balance Sheets and Consolidated Statements of Operations related to our FOREX contracts designated as cash flow hedges for the three-month and nine-month periods ended September 30, 2013 and 2012.
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2013			2012			2013				2012
		(In thousands)
	Amount of gain (loss) recognized in AOCGL on derivative (effective portion)	$	2,486		$	1,720		$	(7,539	)		$	6,191
	Location of loss reclassified from AOCGL into income (effective portion)		Contract			Contract			Contract				Contract
			drilling			drilling			drilling				drilling
			expense			expense			expense				expense
	Amount of loss reclassified from AOCGL into income (effective portion)	$	(5,572	)	$	(2,873	)	$	(2,951	)		$	(5,300	)
	Location of gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)		Foreign			Foreign			Foreign				Foreign
			currency			currency			currency				currency
			transaction			transaction			transaction				transaction
			gain (loss)			gain (loss)			gain (loss)				gain (loss)
	Amount of gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	$	59		$	—		$	(59	)		$	(39	)
	As of September 30, 2013, the estimated amount of net unrealized losses associated with our FOREX contracts that will be reclassified to earnings during the next twelve months was $1.0 million. The net unrealized losses associated with these derivative financial instruments will be reclassified to contract drilling expense. During the three-month and nine-month periods ended September 30, 2013 and 2012, we did not reclassify any amounts from AOCGL due to the probability of an underlying forecasted transaction not occurring.

Financial_Instruments_and_Fair

Financial Instruments and Fair Value Disclosures	9 Months Ended
	Sep. 30, 2013
Fair Value Disclosures [Abstract]
Financial Instruments and Fair Value Disclosures	6. Financial Instruments and Fair Value Disclosures
	Financial instruments which 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, including residential mortgage-backed securities. We generally place our excess cash investments in U.S. government-backed short-term money market instruments through several financial institutions. At times, such investments may be in excess of the insurable limit. We periodically evaluate the relative credit standing of these financial institutions as part of our investment strategy.
	Most of our investments in debt securities are U.S. government securities with minimal credit risk. However, we are exposed to market risk due to price volatility associated with interest rate fluctuations.
	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 consists primarily of major and independent oil and gas companies and government-owned oil companies. At September 30, 2013 and December 31, 2012, our largest customer in Brazil, Petróleo Brasileiro S.A. (a Brazilian multinational energy company that is majority-owned by the Brazilian government) accounted for $120.4 million and $116.4 million, or 28% and 24%, respectively, of our total consolidated gross accounts receivable balance. Our second largest customer in Brazil, OGX Petróleo e Gás Ltda. (a privately owned Brazilian oil and natural gas company), or OGX, accounted for $80.3 million or 17% of our total consolidated gross accounts receivable balance at December 31, 2012. Our accounts receivable balance from OGX was fully reserved at September 30, 2013.
	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 basis when facts and circumstances indicate that a customer receivable may not be collectible and, historically, losses on our trade receivables have been infrequent occurrences.
	During the third quarter of 2013, based on our assessment of the financial condition of two customers, OGX and Niko Resources Ltd., and our expectations regarding the probability of collection of amounts due to us, we recorded $22.6 million in bad debt expense, to reserve the outstanding receivable balances from these customers. All outstanding receivables from these two customers have been fully reserved at September 30, 2013. Our allowance for bad debts was $28.2 million and $5.5 million at September 30, 2013 and December 31, 2012, respectively. We have not recognized any revenue associated with these two customers in the third quarter of 2013. See Note 2.
	At December 31, 2012, $17.2 million in trade accounts receivable was payable to us from a 27% net profits interest, or NPI, in certain developmental oil-and-gas producing properties, which we believe is a real property interest. Our drilling program related to the NPI arrangement was completed in 2011, and the balance of the trade receivable due to us under the NPI arrangement was received in 2013. However, the customer who conveyed the NPI to us filed a voluntary petition for reorganization under Chapter 11 of the Bankruptcy Code on August 17, 2012. Certain parties (including the debtor) in the bankruptcy proceedings have questioned whether our NPI, and certain amounts we have received under it since the filing of the bankruptcy, should be included in the debtor’s estate under the bankruptcy proceeding. We have filed a declaratory judgment action in the bankruptcy court seeking a declaration that our NPI, and payments that we have received from it since the filing of the bankruptcy, are not part of the bankruptcy estate, and we will vigorously defend our rights and pursue our interests in this matter.
	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, U.S. Treasury Bills and Treasury notes. Our Level 1 assets at September 30, 2013 consisted of cash held in money market funds of $385.6 million, time deposits of $20.0 million and investments in U.S. Treasury securities of $800.0 million. Our Level 1 assets at December 31, 2012 consisted of cash held in money market funds of $284.9 million and investments in U.S. Treasury securities of $1,149.9 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. Level 2 assets and liabilities include residential mortgage-backed securities and over-the-counter FOREX contracts. Our residential mortgage-backed securities were valued using a model-derived valuation technique based on the quoted closing market prices received from a financial institution. Our FOREX contracts are valued based on quoted market prices, which are derived from observable inputs including current spot and forward rates, less the contract rate multiplied by the notional amount. The inputs used in our valuation are obtained from a Bloomberg curve analysis which uses par coupon swap rates to calculate implied forward rates so that projected floating rate cash flows can be calculated. The valuation techniques underlying the models are widely accepted in the financial services industry and do not involve significant judgment.
	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 September 30, 2013 and December 31, 2012 consisted of nonrecurring measurements of certain rigs held for sale for which we recorded an impairment loss in 2012. The value of these rigs was determined using a present value technique which utilized unobservable inputs such as assumptions for estimated proceeds that may be received on disposition of each rig and estimated costs to sell. See Note 1.
	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 nine-month periods ended September 30, 2013 and 2012.
	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 did not record any impairment charges related to assets measured at fair value on a nonrecurring basis during the three-month and nine-month periods ended September 30, 2013 and 2012.
	Assets and liabilities measured at fair value are summarized below:
			September 30, 2013
			Fair Value Measurements Using							Assets at Fair
			Level 1		Level 2			Level 3		Value
			(In thousands)
	Recurring fair value measurements:
	Assets:
	Short-term investments		$	1,205,626	$	—		$	—	$	1,205,626
	FOREX contracts			—		3,272			—		3,272
	Mortgage-backed securities			—		224			—		224
	Total assets		$	1,205,626	$	3,496		$	—	$	1,209,122
	Liabilities:
	FOREX contracts		$	—	$	(4,304	)	$	—	$	(4,304	)
	Nonrecurring fair value measurements:
	Assets:
	Assets held for sale		$	—	$	—		$	3,900	$	3,900
			December 31, 2012
			Fair Value Measurements Using							Assets at Fair
			Level 1		Level 2			Level 3		Value
			(In thousands)
	Recurring fair value measurements:
	Assets:
	Short-term investments		$	1,434,751	$	—		$	—	$	1,434,751
	FOREX contracts			—		3,627			—		3,627
	Mortgage-backed securities			—		301			—		301
	Total assets		$	1,434,751	$	3,928		$	—	$	1,438,679
	Liabilities:
	FOREX contracts		$	—	$	(29	)	$	—	$	(29	)
	Nonrecurring fair value measurements:
	Assets:
	Assets held for sale		$	—	$	—		$	3,900	$	3,900
	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 Consolidated Balance Sheets, approximate fair value based on the following assumptions:
		•		Cash and cash equivalents — The carrying amounts approximate fair value because of the short maturity of these instruments.
		•		Accounts receivable and accounts payable — The carrying amounts approximate fair value based on the nature of the instruments.
	We consider our long-term debt, including current maturities, to be Level 2 liabilities under the GAAP fair value hierarchy and, accordingly, the fair value of our 5.70% Senior Notes due 2039, 5.875% Senior Notes due 2019, 4.875% Senior Notes due July 1, 2015, and 5.15% Senior Notes due September 1, 2014 was derived using a third-party pricing service at September 30, 2013 and December 31, 2012. 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 around the report date. Fair values and related carrying values of our long-term debt instruments are shown below.
			September 30, 2013					December 31, 2012
			Fair Value		Carrying Value			Fair Value		Carrying Value
			(In millions)
	4.875% Senior Notes		$	268.1	$	249.9		$	275.5	$	249.8
	5.15% Senior Notes			260		249.9			269		249.9
	5.70% Senior Notes			567.9		496.9			641.4		496.9
	5.875% Senior Notes			587.1		499.5			617.1		499.5
	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_an

Drilling and Other Property and Equipment	9 Months Ended
	Sep. 30, 2013
Property Plant And Equipment [Abstract]
Drilling and Other Property and Equipment	7. Drilling and Other Property and Equipment
	Cost and accumulated depreciation of drilling and other property and equipment are summarized as follows:
		September 30,			December 31,
		2013			2012
		(In thousands)
	Drilling rigs and equipment	$	7,295,964		$	7,107,279
	Construction work-in-progress		1,553,430			990,964
	Land and buildings		65,362			64,296
	Office equipment and other		64,891			60,239
	Cost		8,979,647			8,222,778
	Less: accumulated depreciation		(3,648,177	)		(3,357,806	)
	Drilling and other property and equipment, net	$	5,331,470		$	4,864,972
	Construction work-in-progress, including capitalized interest, at September 30, 2013 and December 31, 2012 is summarized as follows:
		September 30,			December 31,
		2013			2012
		(In thousands)
	Ultra-deepwater drillships	$	834,476		$	741,059
	Ultra-deepwater semisubmersible:
	Ocean GreatWhite		192,311			—
	Deepwater semisubmersibles:
	Ocean Onyx		299,886			167,403
	Ocean Apex		226,757			82,502
	Total construction work-in-progress	$	1,553,430		$	990,964

Commitments_and_Contingencies

Commitments and Contingencies	9 Months Ended
	Sep. 30, 2013
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	8. 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 determined, we record a liability for the amount of the 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.
	Litigation. We are one of several unrelated defendants in lawsuits filed in state courts alleging that defendants manufactured, distributed or utilized drilling mud containing asbestos and, in our case, allowed such drilling mud to have been utilized aboard our offshore drilling rigs. The plaintiffs seek, among other things, an award of unspecified compensatory and punitive damages. The manufacture and use of asbestos-containing drilling mud had already ceased before we acquired any of the drilling rigs addressed in these lawsuits. We believe that we are not liable for the damages asserted and we expect to receive complete defense and indemnity with respect to a majority of the lawsuits from Murphy Exploration & Production Company pursuant to the terms of our 1992 asset purchase agreement with them. We also believe that we are not liable for the damages asserted in the remaining lawsuits pursuant to the terms of our 1989 asset purchase agreement with Diamond M Corporation, and we filed a declaratory judgment action in Texas state court against NuStar Energy LP, or NuStar, the successor to Diamond M Corporation, seeking a judicial determination that we did not assume liability for these claims. We obtained summary judgment on our claims in the declaratory judgment action, but NuStar appealed the trial court’s decision, and the appellate court has remanded the case to trial. We are unable to estimate our potential exposure, if any, to these lawsuits at this time but do not believe that ultimate liability, if any, resulting from this litigation will have a material effect on our consolidated financial condition, results of operations and cash flows.
	Various other claims have been filed against us in the ordinary course of business. In the opinion of our management, no pending or known threatened claims, actions or proceedings against us are expected to have a material adverse effect on our consolidated financial position, results of operations and cash flows.
	We intend to defend these matters vigorously; however, we cannot predict with certainty the outcome or effect of any litigation matters specifically described above or any other pending litigation or claims. There can be no assurance as to the ultimate outcome of these lawsuits.
	Personal Injury Claims. Our deductibles for marine liability insurance coverage, including personal injury claims, which primarily result from Jones Act liability in the Gulf of Mexico, are currently $10.0 million for the first occurrence, with no aggregate deductible, and vary in amounts ranging between $5.0 million and, if aggregate claims exceed certain thresholds, up to $100.0 million for each subsequent occurrence, depending on the nature, severity and frequency of claims which might arise during the policy year. 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 September 30, 2013, our estimated liability for personal injury claims was $35.5 million, of which $8.1 million and $27.4 million were recorded in “Accrued liabilities” and “Other liabilities,” respectively, in our Consolidated Balance Sheets. At December 31, 2012, our estimated liability for personal injury claims was $36.1 million, of which $9.9 million and $26.2 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.
	Purchase Obligations
	Ultra-Deepwater Floater Construction. In May 2013, we entered into an agreement with Hyundai Heavy Industries, Co., Ltd., or Hyundai, for the construction of a 10,000 foot dynamically positioned, harsh environment semisubmersible drilling rig. The Ocean GreatWhite is under construction in South Korea at an estimated cost of $755 million, including capital spares, commissioning and shipyard supervision. The contracted price to Hyundai totaling $628.5 million is payable in two installments, of which the first installment of $188.6 million has been paid. The final installment of $439.9 million is due upon delivery of the rig, which is expected to occur in the first quarter of 2016.
	Drillship Construction. We are financially obligated under four separate turnkey construction contracts with Hyundai for the construction of four ultra-deepwater drillships. We expect the aggregate cost of the construction of our drillships, including commissioning, capital spares and project management costs, to be approximately $2.6 billion. The contracted price of each drillship is payable to Hyundai in two installments, with final payment due on delivery of each drillship. We have paid the first installment for each of the four drillships, aggregating $647.6 million. The Ocean BlackHawk and Ocean BlackHornet are expected to be delivered in the fourth quarter of 2013 and in the first quarter of 2014, respectively, and, at those times, the second installment of approximately $394 million will be payable to Hyundai for each rig. The Ocean BlackRhino and Ocean BlackLion are expected to be delivered in the second and fourth quarters of 2014, respectively, at which times approximately $395 million will be payable to Hyundai for each rig.
	Ocean Onyx Construction. We are obligated under a vessel modification agreement with Keppel AmFELS, L.L.C., or Keppel, for the construction of the Ocean Onyx, a moored semisubmersible deepwater rig, which is expected to be delivered in the fourth quarter of 2013. We estimate the aggregate cost for the construction of the Ocean Onyx to be approximately $335.0 million, including commissioning, capital spares and project management costs. The contracted price due to Keppel is payable in 11 installments based on the occurrence of certain events as detailed in the vessel modification agreement. To date, we have paid the first nine installments, of which $58.4 million and $65.7 million was paid in 2013 and 2012, respectively. The balance payable to Keppel under the construction agreement of $21.9 million is payable in the fourth quarter of 2013.
	Ocean Apex Construction. We are obligated under a vessel modification agreement with Jurong Shipyard Pte Ltd, or Jurong, for the construction of the Ocean Apex, a moored semisubmersible deepwater rig, which is expected to be delivered in the third quarter of 2014 at an aggregate cost of approximately $370.0 million, including commissioning, capital spares and project management costs. The contracted price due to Jurong is payable in 12 installments based on the occurrence of certain events as detailed in the vessel modification agreement. We have paid the first five installments, of which $33.8 million and $27.0 million was paid in 2013 and 2012, respectively. The remaining $74.3 million in aggregate milestone payments are payable to Jurong during the remainder of 2013 and in 2014 as construction milestones are met.
	Ocean Patriot Enhancements. In February 2013, we entered into a vessel modification agreement with Keppel FELS Limited, or Keppel Singapore, for enhancements to the Ocean Patriot that will enable the rig to work in the North Sea. We estimate the cost of the enhancement project to be approximately $120.0 million, including shipyard costs, owner-furnished equipment and labor, commissioning and capital spares. Construction work is expected to begin in Singapore in the fourth quarter of 2013 and to be completed in the second quarter of 2014. The contracted price due Keppel Singapore is approximately $29.0 million, payable in seven installments based on the occurrence of certain events as detailed in the vessel modification agreement. We paid the first two installments due to Keppel Singapore aggregating $10.1 million in 2013. The remaining $18.8 million in aggregate milestone payments are payable to Keppel Singapore during the remainder of 2013 and in 2014 as construction milestones are met.
	At September 30, 2013 and December 31, 2012, we had no other purchase obligations for major rig upgrades or any other significant obligations, except for those related to our direct rig operations, which arise during the normal course of business.
	Letters of Credit and Other. We were contingently liable as of September 30, 2013 in the amount of $70.2 million under certain performance, bid, supersedeas and custom bonds and letters of credit. Agreements relating to approximately $58.2 million of performance, supersedeas and customs bonds can require collateral at any time. As of September 30, 2013, we had not been required to make any collateral deposits with respect to these agreements. The remaining agreements cannot require collateral except in events of default. On our behalf, banks have issued letters of credit securing certain of these bonds.

Accumulated_Other_Comprehensiv

Accumulated Other Comprehensive Gain (Loss)	9 Months Ended
	Sep. 30, 2013
Equity [Abstract]
Accumulated Other Comprehensive Gain (Loss)	9. Accumulated Other Comprehensive Gain (Loss)
	The components of our AOCGL and related changes thereto are as follows:
		Unrealized Gain (Loss) on
		FOREX			Marketable			Total
		Contracts			Securities			AOCGL
		(In thousands)
	Balance at January 1, 2013	$	2,350		$	146		$	2,496
	Change in other comprehensive gain (loss) before reclassifications, after tax of $2,638 and $6		(4,901	)		7			(4,894	)
	Reclassification adjustments for items included in Net Income, after tax of $(1,033) and $19		1,918			(146	)		1,772
	Balance at September 30, 2013	$	(633	)	$	7		$	(626	)
	The following table presents the line items in our Consolidated Statements of Operations affected by reclassification adjustments out of AOCGL.
	Major Category of AOCGL	Three Months			Nine Months			Consolidated Statements of
		Ended			Ended			Operations Line Items
		September 30, 2013
		(In thousands)
	Unrealized (gain) loss on FOREX contracts	$	5,572		$	2,951		Contract drilling, excluding depreciation
			(1,950	)		(1,033	)	Income tax expense
		$	3,622		$	1,918		Net of tax
	Unrealized (gain) loss on marketable securities	$	(15	)	$	(165	)	Other, net
			1			19		Income tax expense
		$	(14	)	$	(146	)	Net of tax

Segments_and_Geographic_Area_A

Segments and Geographic Area Analysis	9 Months Ended
	Sep. 30, 2013
Segment Reporting [Abstract]
Segments and Geographic Area Analysis	10. 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 earnings process as it relates to the offshore drilling industry over the operating lives of our drilling rigs.
	Revenues from contract drilling services by equipment type are listed below:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2013		2012		2013		2012
		(In thousands)
	Floaters:
	Ultra-Deepwater	$	195,215	$	195,574	$	617,673	$	673,233
	Deepwater		147,333		163,816		495,858		452,384
	Mid-Water		297,368		319,491		891,449		948,548
	Total Floaters		639,916		678,881		2,004,980		2,074,165
	Jack-ups		50,825		35,146		130,632		121,278
	Total contract drilling revenues		690,741		714,027		2,135,612		2,195,443
	Revenues related to reimbursable expenses		15,424		15,114		58,312		40,528
	Total revenues	$	706,165	$	729,141	$	2,193,924	$	2,235,971
	Geographic Areas
	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 September 30, 2013, our actively-marketed drilling rigs were en route to or located offshore 13 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.
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2013		2012		2013		2012
		(In thousands)
	United States	$	69,627	$	49,443	$	253,654	$	146,009
	International:
	South America		311,708		360,617		896,029		1,084,210
	Europe/Africa/Mediterranean		185,335		162,324		559,290		484,229
	Australia/Asia		88,054		111,850		333,728		379,240
	Mexico		51,441		44,907		151,223		142,283
	Total revenues	$	706,165	$	729,141	$	2,193,924	$	2,235,971

Income_Taxes

Income Taxes	9 Months Ended
	Sep. 30, 2013
Income Tax Disclosure [Abstract]
Income Taxes	11. Income Taxes
	Our income tax expense is a function of the mix between our domestic and international pre-tax earnings or losses, as well as the mix of international tax jurisdictions in which we operate. Certain of our international rigs are owned and operated, directly or indirectly, by one of our wholly owned foreign subsidiaries. It is our intention to indefinitely reinvest future earnings of this subsidiary to finance foreign activities. Accordingly, we have not made a provision for U.S. income taxes on such earnings except to the extent that such earnings were immediately subject to U.S. income taxes.
	During the first quarter of 2013, our tax expense was reduced by $27.5 million as a result of the American Taxpayer Relief Act of 2012, or the Act, which was signed into law on January 2, 2013. The Act extends through 2013 several expired temporary business provisions, commonly referred to as “extenders,” which were retroactively extended to the beginning of 2012. As required by GAAP, we recorded the retroactive effect of the extenders when the Act was signed into law.
	Tax Returns and Examinations. We file income tax returns in the U.S. federal jurisdiction, various state jurisdictions and various foreign jurisdictions. Tax years that remain subject to examination by these jurisdictions include years 2003 to 2012. We are currently under audit in several of these jurisdictions. We do not anticipate that any adjustments resulting from the tax audit of any of these years will have a material impact on our consolidated results of operations, financial condition and cash flows.
	Mexico Tax Jurisdiction. The tax authorities in Mexico previously audited our income tax returns for the years 2004 and 2006 and had issued assessments for tax years 2004 and 2006 of approximately $22.9 million and $24.4 million, respectively, including interest and penalties, which we had appealed. In 2013 the Mexican tax authorities initiated a tax amnesty program whereby income tax assessments, including penalties and interest, could be partially or completely waived. Under the tax amnesty we were able to settle our tax liabilities for the years 2004 and 2006 for a net cash cost of $3.7 million. As a result of increases in uncertain tax positions for later years, we recorded an additional $13.2 million of expense, including $5.0 million of interest and $2.7 million of penalties.
	Due to the expiration of the statute of limitations in Mexico for the 2007 tax year at the end of June 2013, during the second quarter of 2013, we reversed our $4.3 million accrual for this uncertain tax position, of which $1.5 million was interest and $0.6 million was penalty.
	On June 13, 2013 we received official notification that the Mexican tax authorities will be auditing the 2008 income tax return of one of our Mexican subsidiaries.
	U.S. Tax Jurisdiction. In May 2013, we were notified by the Department of the Treasury that the Internal Revenue Service audit of our 2010 corporate tax return was completed without adjustment.
	Brazil Tax Jurisdiction. In March 2013, the Brazilian tax authorities began an audit of our income tax returns for the years 2009 and 2010. We are continuing to defend tax assessments by the Brazilian tax authorities for the years 2000, 2004, 2005 and 2007.

General_Information_Policies

General Information (Policies)

9 Months Ended

Sep. 30, 2013

Accounting Policies [Abstract]

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.

Reclassifications

Reclassifications

Certain amounts applicable to the prior periods have been reclassified to conform to the classifications currently followed. Such reclassifications do not affect earnings.

Cash and Cash Equivalents

Cash and Cash Equivalents

We consider short-term, highly liquid investments that have an original maturity of three months or less and deposits in money market mutual funds that are readily convertible into cash to be cash equivalents.

The effect of exchange rate changes on cash balances held in foreign currencies was not material for each of the three and nine-month periods ended September 30, 2013 and 2012.

Marketable Securities

Marketable Securities

We classify our investments in marketable securities as available for sale and they are stated at fair value in our Consolidated Balance Sheets. Accordingly, any unrealized gains and losses, net of taxes, are reported in our Consolidated Balance Sheets in “Accumulated other comprehensive gain (loss),” or AOCGL, until realized. The cost of debt securities is adjusted for amortization of premiums and accretion of discounts to maturity and such adjustments are included in our Consolidated Statements of Operations in “Interest income.” The sale and purchase of securities are recorded on the date of the trade. The cost of debt securities sold is based on the specific identification method. Realized gains or losses, as well as any declines in value that are judged to be other than temporary, are reported in our Consolidated Statements of Operations in “Other income (expense) – Other, net.” See Note 4.

Provision for Bad Debts

Provision for Bad Debts

We record a provision for bad debts on a case-by-case basis when facts and circumstances indicate that a customer receivable may not be collectible. In establishing these reserves, we consider historical and other factors that predict collectability, including write-offs, recoveries and the monitoring of credit quality. Such provision is reported as a component of “Operating expenses” in our Consolidated Statements of Operations. See Note 2.

Derivative Financial Instruments

Derivative Financial Instruments

Our derivative financial instruments consist of foreign currency forward exchange, or FOREX, contracts which we may designate as cash flow hedges. In accordance with GAAP, each derivative contract is stated in the balance sheet at its fair value with gains and losses reflected in the income statement except that, to the extent the derivative qualifies for and is designated as an accounting hedge, the gains and losses are reflected in income in the same period as offsetting gains and losses on the qualifying hedged positions. Designated hedges are expected to be highly effective, and therefore, adjustments to record the carrying value of the effective portion of our derivative financial instruments to their fair value are recorded as a component of AOCGL in our Consolidated Balance Sheets. The effective portion of the cash flow hedge will remain in AOCGL until it is reclassified into earnings in the period or periods during which the hedged transaction affects earnings or it is determined that the hedged transaction will not occur. We report such realized gains and losses as a component of “Contract drilling, excluding depreciation” expense in our Consolidated Statements of Operations to offset the impact of foreign currency fluctuations in our expenditures in local foreign currencies in the countries in which we operate. See Note 9.

Adjustments to record the carrying value of the ineffective portion of our derivative financial instruments to fair value and realized gains or losses upon settlement of derivative contracts not designated as cash flow hedges are reported as “Foreign currency transaction gain (loss)” in our Consolidated Statements of Operations. See Notes 5 and 6.

Assets Held for Sale

Assets Held For Sale

In 2012, our management adopted a plan to actively market for sale three cold-stacked mid-water semisubmersibles (the Ocean Epoch, the Ocean New Era and the Ocean Whittington) and one cold-stacked jack-up rig (the Ocean Spartan). In connection with the reclassification of these rigs to “Assets held for sale,” we measured the fair value of each rig in the disposal group using a probability-weighted cash flow analysis that utilized significant unobservable inputs, representing a Level 3 fair value measurement, which included assumptions for estimated proceeds that may be received upon disposition of the rig and estimated costs to sell. For our three mid-water semisubmersibles in the disposal group, we determined that, due to the expected resale market for rigs of this type and age, the highest and best use of these rigs would be for sale as scrap. Based on our analyses, we determined that the carrying values of the mid-water semisubmersible rigs in the disposal group were impaired, as the carrying value for each exceeded its aggregate fair value, and recognized an impairment loss in the fourth quarter of 2012. We determined that the carrying value of the Ocean Spartan was not impaired. At both September 30, 2013 and December 31, 2012, we reported “Assets held for sale” aggregating $11.6 million in our Consolidated Balance Sheets. See Note 6.

Drilling and Other Property and Equipment

Drilling and Other Property and Equipment

We carry our drilling and other property and equipment at cost. Maintenance and routine repairs are charged to income currently while replacements and betterments, which upgrade or increase the functionality of our existing equipment and that significantly extend the useful life of an existing asset, are capitalized. Significant judgments, assumptions and estimates may be required in determining whether or not such replacements and betterments meet the criteria for capitalization and in determining useful lives and salvage values of such assets. Changes in these judgments, assumptions and estimates could produce results that differ from those reported. Historically, the amount of capital additions requiring significant judgments, assumptions or estimates has not been significant. During the nine months ended September 30, 2013 and the year ended December 31, 2012, we capitalized $189.2 million and $220.3 million, respectively, in replacements and betterments of our drilling fleet, resulting from numerous projects ranging from $25,000 to $60 million per project.

Costs incurred for major rig upgrades and/or the construction of rigs are accumulated in construction work-in-progress, with no depreciation recorded on the additions, until the month the upgrade or newbuild is completed and the rig is placed in service. Upon retirement or sale of a rig, the cost and related accumulated depreciation are removed from the respective accounts and any gains or losses are included in our results of operations as “Gain on disposition of assets.” Depreciation is recognized up to applicable salvage values by applying the straight-line method over the remaining estimated useful lives from the year the asset is placed in service. Drilling rigs and equipment are depreciated over their estimated useful lives ranging from three to 30 years.

Capitalized Interest

Capitalized Interest

We capitalize interest cost for qualifying construction and upgrade projects. See Note 7. A reconciliation of our total interest cost to “Interest expense” as reported in our Consolidated Statements of Operations is as follows:

Three Months Ended

Nine Months Ended

September 30,

September 30,

2013

2012

2013

2012

(In thousands)

Total interest cost, including amortization of debt issuance costs

$

22,234

$

19,145

$

71,229

$

62,782

Capitalized interest

(20,541

)

(10,425

)

(53,516

)

(26,002

)

Total interest expense as reported

$

1,693

$

8,720

$

17,713

$

36,780

Impairment of Long-Lived Assets

Impairment of Long-Lived Assets

We evaluate our property and equipment for impairment whenever changes in circumstances indicate that the carrying amount of an asset may not be recoverable, such as cold stacking a rig or excess spending over budget on a newbuild, construction project or major rig upgrade. There were no cold-stacked rigs at September 30, 2013 that were not being marketed for sale.

Current Portion of Long-Term Debt

Current Portion of Long-Term Debt

Our 5.15% Senior Notes due September 1, 2014, or 5.15% Senior Notes, in the aggregate principal amount of $250.0 million will mature on September 1, 2014. Accordingly, the aggregate $249.9 million accreted value of our 5.15% Senior Notes has been presented as “Current portion of long-term debt” in our Consolidated Balance Sheets at September 30, 2013.

Foreign Currency

Foreign Currency

Our functional currency is the U.S. dollar. Foreign currency transaction gains and losses are reported as “Foreign currency transaction gain (loss)” in our Consolidated Statements of Operations and include, when applicable, unrealized gains and losses to record the carrying value of our FOREX contracts not designated as accounting hedges, as well as realized gains and losses from the settlement of such contracts. For the three-month and nine-month periods ended September 30, 2013, we recognized net foreign currency transaction (losses) of $(4.6) million and $(3.9) million, respectively. For the three-month and nine-month periods ended September 30, 2012, we recognized net foreign currency transaction (losses) of $(1.9) million and $(0.9) million, respectively. See Note 5.

Revenue Recognition

Revenue Recognition

We recognize revenue from dayrate drilling contracts as services are performed. In connection with such drilling contracts, we may receive fees (either lump-sum or dayrate) for the mobilization of equipment. We earn these fees as services are performed over the initial term of the related drilling contracts. We defer mobilization fees received, as well as direct and incremental mobilization costs incurred, and amortize each, on a straight-line basis, over the term of the related drilling contracts (which is the period we estimate to be benefited from the mobilization activity). Straight-line amortization of mobilization revenues and related costs over the term of the related drilling contracts (which generally range from two to 60 months) is consistent with the timing of net cash flows generated from the actual drilling services performed. Absent a contract, mobilization costs are recognized currently.

Some of our drilling contracts require downtime before the start of the contract to prepare the rig to meet customer requirements. At times, we may be compensated by the customer for such work (either lump-sum or dayrate). These fees are generally earned as services are performed over the initial term of the related drilling contracts. We defer contract preparation fees received as well as direct and incremental costs associated with the contract preparation activities and amortize each, on a straight-line basis, over the term of the related drilling contracts (which we estimate to be benefited from the contract preparation activity).

From time to time, we may receive fees from our customers for capital improvements to our rigs (either lump-sum or dayrate). We defer such fees received in “Accrued liabilities” and “Other liabilities” in our Consolidated Balance Sheets and recognize these fees into income on a straight-line basis over the period of the related drilling contract. We capitalize the costs of such capital improvements and depreciate them over the estimated useful life of the improvement.

We record reimbursements received for the purchase of supplies, equipment, personnel services and other services provided at the request of our customers in accordance with a contract or agreement, for the gross amount billed to the customer, as “Revenues related to reimbursable expenses” in our Consolidated Statements of Operations.

Recent Accounting Pronouncements

Recent Accounting Pronouncements

In July 2013, the Financial Accounting Standards Board issued Accounting Standards Update 2013-11, or ASU 2013-11, which eliminates diversity in practice for the presentation of an unrecognized tax benefit when a net operating loss carryforward, a similar tax loss or a tax credit carryforward is available to reduce the taxable income or tax payable that would result from disallowance of a tax position. ASU 2013-11 affects only the presentation of such amounts in an entity’s balance sheet and is effective for fiscal years beginning after December 15, 2013 and interim periods within those years. Early adoption is permitted. We are evaluating the impact, if any, of the adoption of ASU 2013-11 on our consolidated balance sheets.

General_Information_Tables

General Information (Tables)	9 Months Ended
	Sep. 30, 2013
Accounting Policies [Abstract]
Reconciliation of Total Interest Cost to Interest Expense	A reconciliation of our total interest cost to “Interest expense” as reported in our Consolidated Statements of Operations is as follows:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2013			2012			2013			2012
		(In thousands)
	Total interest cost, including amortization of debt issuance costs	$	22,234		$	19,145		$	71,229		$	62,782
	Capitalized interest		(20,541	)		(10,425	)		(53,516	)		(26,002	)
	Total interest expense as reported	$	1,693		$	8,720		$	17,713		$	36,780

Supplemental_Financial_Informa1

Supplemental Financial Information (Tables)	9 Months Ended
	Sep. 30, 2013
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Accounts Receivable, Net of Allowance for Doubtful Accounts	Accounts receivable, net of allowance for bad debts, consists of the following:
			September 30,			December 31,
			2013			2012
			(In thousands)
	Trade receivables		$	422,708		$	478,987
	Value added tax receivables			17,750			13,884
	Amounts held in escrow			12,025			11,555
	Related party receivables			353			527
	Other			124			165
				452,960			505,118
	Allowance for bad debts			(28,152	)		(5,458	)
	Total		$	424,808		$	499,660
Prepaid Expenses and Other Current Assets	Prepaid expenses and other current assets consist of the following:
			September 30,			December 31,
			2013			2012
			(In thousands)
	Rig spare parts and supplies		$	52,195		$	57,558
	Deferred mobilization costs			23,974			38,074
	Prepaid insurance			20,329			12,549
	Deferred tax assets			8,619			8,619
	Prepaid taxes			25,892			5,950
	FOREX contracts			3,272			3,627
	Other			7,871			9,722
	Total		$	142,152		$	136,099
Accrued Liabilities	Accrued liabilities consist of the following:
			September 30,			December 31,
			2013			2012
			(In thousands)
	Rig operating expenses		$	87,069		$	70,078
	Payroll and benefits			107,210			88,612
	Deferred revenue			34,457			71,699
	Accrued capital project/upgrade costs			74,308			56,595
	Interest payable			29,422			21,219
	Personal injury and other claims			10,065			10,312
	FOREX contracts			4,304			29
	Other			7,397			5,890
	Total		$	354,232		$	324,434
Noncash Investing and Financing Activities	Consolidated Statements of Cash Flows Information
	Noncash investing activities excluded from the Consolidated Statements of Cash Flows and other supplemental cash flow information is as follows:
			Nine Months Ended
			September 30,
			2013			2012
			(In thousands)
	Accrued but unpaid capital expenditures at period end		$	74,308		$	48,620
	Cash interest payments(1)(2)			54,000			54,187
	Cash income taxes paid, net of refunds:
	U.S. federal			47,000			53,000
	Foreign			62,951			56,070
	State			190			212
	-1	Interest payments, net of amounts capitalized, were $8.9 million and $31.9 million for the nine months ended September 30, 2013 and 2012, respectively.
	-2	Interest paid on Internal Revenue Service assessments was $0.2 million during the nine months ended September 30, 2012.

Earnings_Per_Share_Tables

Earnings Per Share (Tables)	9 Months Ended
	Sep. 30, 2013
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 computations follows:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2013		2012		2013		2012
		(In thousands, except per share data)
	Net income – basic and diluted numerator:	$	94,748	$	178,186	$	456,071	$	564,816
	Weighted average shares – basic (denominator):		139,035		139,030		139,034		139,029
	Effect of dilutive potential shares
	Stock options and stock appreciation rights		30		23		38		17
	Weighted average shares including conversions – diluted (denominator)		139,065		139,053		139,072		139,046
	Earnings per share:
	Basic	$	0.68	$	1.28	$	3.28	$	4.06
	Diluted	$	0.68	$	1.28	$	3.28	$	4.06
Securities Excluded from Computation of Diluted Earning Per Share	The following table sets forth the share effects of stock options and the number of stock appreciation rights excluded from our computations of diluted earnings per share, or EPS, as the inclusion of such potentially dilutive shares would have been antidilutive for the periods presented:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2013		2012		2013		2012
		(In thousands)
	Employee and director:
	Stock options		18		18		18		18
	Stock appreciation rights		982		874		885		900

Marketable_Securities_Tables

Marketable Securities (Tables)	9 Months Ended
	Sep. 30, 2013
Investments Debt And Equity Securities [Abstract]
Investments in Marketable Securities as Available for Sale	Our investments in marketable securities are classified as available for sale and are summarized as follows:
		September 30, 2013
		Amortized			Unrealized			Market
		Cost			Gain (Loss)			Value
		(In thousands)
	U.S. Treasury Bills and Notes (due within one year)	$	799,981		$	(1	)	$	799,980
	Mortgage-backed securities		212			12			224
	Total	$	800,193		$	11		$	800,204
		31-Dec-12
		Amortized			Unrealized			Market
		Cost			Gain (Loss)			Value
		(In thousands)
	U.S. Treasury Bills and Notes (due within one year)	$	1,149,707		$	150		$	1,149,857
	Mortgage-backed securities		276			25			301
	Total	$	1,149,983		$	175		$	1,150,158
Summary of Proceeds from Sales and Maturities of Marketable Securities and Gross Realized Gains and Losses	Proceeds from maturities and sales of marketable securities and gross realized gains and losses are summarized as follows:
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2013			2012			2013			2012
		(In thousands)
	Proceeds from maturities	$	1,475,000		$	675,000		$	3,225,000		$	1,925,000
	Proceeds from sales		25			56			62			150,106
	Gross realized gains		—			—			—			—
	Gross realized losses		(1	)		(1	)		(1	)		(6	)

Derivative_Financial_Instrumen1

Derivative Financial Instruments (Tables)	9 Months Ended
	Sep. 30, 2013
Derivative Instruments And Hedging Activities Disclosure [Abstract]
Amounts Recognized in our Consolidated Statements of Operations Related to our FOREX Contracts Designated as Accounting Hedges	The following table presents the aggregate amount of loss recognized in our Consolidated Statements of Operations related to our FOREX contracts designated as accounting hedges for the three-month and nine-month periods ended September 30, 2013 and 2012.
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
	Location of Loss Recognized in Income	2013			2012			2013				2012
		(In thousands)
	Contract drilling expense	$	(5,018	)	$	(2,715	)	$	(2,246	)		$	(5,692	)
Fair Values of our Derivative Financial Instruments	The following table presents the fair values of our derivative FOREX contracts designated as hedging instruments at September 30, 2013 and December 31, 2012.
		Fair Value						Balance Sheet Location		Fair Value
	Balance Sheet Location	September 30,			December 31,					September 30,				December 31,
		2013			2012					2013				2012
		(In thousands)								(In thousands)
	Prepaid expenses and other current assets	$	3,272		$	3,627		Accrued liabilities		$	(4,304	)		$	(29	)
Amounts Recognized in our Consolidated Balance Sheets and Consolidated Statements of Operations Related to our FOREX Contracts Designated as Cash Flow Hedges	The following table presents the amounts recognized in our Consolidated Balance Sheets and Consolidated Statements of Operations related to our FOREX contracts designated as cash flow hedges for the three-month and nine-month periods ended September 30, 2013 and 2012.
		Three Months Ended						Nine Months Ended
		September 30,						September 30,
		2013			2012			2013				2012
		(In thousands)
	Amount of gain (loss) recognized in AOCGL on derivative (effective portion)	$	2,486		$	1,720		$	(7,539	)		$	6,191
	Location of loss reclassified from AOCGL into income (effective portion)		Contract			Contract			Contract				Contract
			drilling			drilling			drilling				drilling
			expense			expense			expense				expense
	Amount of loss reclassified from AOCGL into income (effective portion)	$	(5,572	)	$	(2,873	)	$	(2,951	)		$	(5,300	)
	Location of gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)		Foreign			Foreign			Foreign				Foreign
			currency			currency			currency				currency
			transaction			transaction			transaction				transaction
			gain (loss)			gain (loss)			gain (loss)				gain (loss)
	Amount of gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	$	59		$	—		$	(59	)		$	(39	)

Financial_Instruments_and_Fair1

Financial Instruments and Fair Value Disclosures (Tables)	9 Months Ended
	Sep. 30, 2013
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:
		September 30, 2013
		Fair Value Measurements Using							Assets at Fair
		Level 1		Level 2			Level 3		Value
		(In thousands)
	Recurring fair value measurements:
	Assets:
	Short-term investments	$	1,205,626	$	—		$	—	$	1,205,626
	FOREX contracts		—		3,272			—		3,272
	Mortgage-backed securities		—		224			—		224
	Total assets	$	1,205,626	$	3,496		$	—	$	1,209,122
	Liabilities:
	FOREX contracts	$	—	$	(4,304	)	$	—	$	(4,304	)
	Nonrecurring fair value measurements:
	Assets:
	Assets held for sale	$	—	$	—		$	3,900	$	3,900
		December 31, 2012
		Fair Value Measurements Using							Assets at Fair
		Level 1		Level 2			Level 3		Value
		(In thousands)
	Recurring fair value measurements:
	Assets:
	Short-term investments	$	1,434,751	$	—		$	—	$	1,434,751
	FOREX contracts		—		3,627			—		3,627
	Mortgage-backed securities		—		301			—		301
	Total assets	$	1,434,751	$	3,928		$	—	$	1,438,679
	Liabilities:
	FOREX contracts	$	—	$	(29	)	$	—	$	(29	)
	Nonrecurring fair value measurements:
	Assets:
	Assets held for sale	$	—	$	—		$	3,900	$	3,900
Fair Values and Related Carrying Values of Our Debt Instruments	Fair values and related carrying values of our long-term debt instruments are shown below.
		September 30, 2013					December 31, 2012
		Fair Value		Carrying Value			Fair Value		Carrying Value
		(In millions)
	4.875% Senior Notes	$	268.1	$	249.9		$	275.5	$	249.8
	5.15% Senior Notes		260		249.9			269		249.9
	5.70% Senior Notes		567.9		496.9			641.4		496.9
	5.875% Senior Notes		587.1		499.5			617.1		499.5

Drilling_and_Other_Property_an1

Drilling and Other Property and Equipment (Tables)	9 Months Ended
	Sep. 30, 2013
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:
		September 30,			December 31,
		2013			2012
		(In thousands)
	Drilling rigs and equipment	$	7,295,964		$	7,107,279
	Construction work-in-progress		1,553,430			990,964
	Land and buildings		65,362			64,296
	Office equipment and other		64,891			60,239
	Cost		8,979,647			8,222,778
	Less: accumulated depreciation		(3,648,177	)		(3,357,806	)
	Drilling and other property and equipment, net	$	5,331,470		$	4,864,972
Summary of Construction Work-in-Progress, Including Capitalized Interest	Construction work-in-progress, including capitalized interest, at September 30, 2013 and December 31, 2012 is summarized as follows:
		September 30,			December 31,
		2013			2012
		(In thousands)
	Ultra-deepwater drillships	$	834,476		$	741,059
	Ultra-deepwater semisubmersible:
	Ocean GreatWhite		192,311			—
	Deepwater semisubmersibles:
	Ocean Onyx		299,886			167,403
	Ocean Apex		226,757			82,502
	Total construction work-in-progress	$	1,553,430		$	990,964

Accumulated_Other_Comprehensiv1

Accumulated Other Comprehensive Gain (Loss) (Tables)	9 Months Ended
	Sep. 30, 2013
Equity [Abstract]
Components of Accumulated Other Comprehensive Gain Loss	The components of our AOCGL and related changes thereto are as follows:
		Unrealized Gain (Loss) on
		FOREX			Marketable			Total
		Contracts			Securities			AOCGL
		(In thousands)
	Balance at January 1, 2013	$	2,350		$	146		$	2,496
	Change in other comprehensive gain (loss) before reclassifications, after tax of $2,638 and $6		(4,901	)		7			(4,894	)
	Reclassification adjustments for items included in Net Income, after tax of $(1,033) and $19		1,918			(146	)		1,772
	Balance at September 30, 2013	$	(633	)	$	7		$	(626	)
Changes in Accumulated Other Comprehensive Income Loss	The following table presents the line items in our Consolidated Statements of Operations affected by reclassification adjustments out of AOCGL.
	Major Category of AOCGL	Three Months			Nine Months			Consolidated Statements of
		Ended			Ended			Operations Line Items
		September 30, 2013
		(In thousands)
	Unrealized (gain) loss on FOREX contracts	$	5,572		$	2,951		Contract drilling, excluding depreciation
			(1,950	)		(1,033	)	Income tax expense
		$	3,622		$	1,918		Net of tax
	Unrealized (gain) loss on marketable securities	$	(15	)	$	(165	)	Other, net
			1			19		Income tax expense
		$	(14	)	$	(146	)	Net of tax

Segments_and_Geographic_Area_A1

Segments and Geographic Area Analysis (Tables)	9 Months Ended
	Sep. 30, 2013
Segment Reporting [Abstract]
Revenues from Contract Drilling Services by Equipment Type	Revenues from contract drilling services by equipment type are listed below:
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2013		2012		2013		2012
		(In thousands)
	Floaters:
	Ultra-Deepwater	$	195,215	$	195,574	$	617,673	$	673,233
	Deepwater		147,333		163,816		495,858		452,384
	Mid-Water		297,368		319,491		891,449		948,548
	Total Floaters		639,916		678,881		2,004,980		2,074,165
	Jack-ups		50,825		35,146		130,632		121,278
	Total contract drilling revenues		690,741		714,027		2,135,612		2,195,443
	Revenues related to reimbursable expenses		15,424		15,114		58,312		40,528
	Total revenues	$	706,165	$	729,141	$	2,193,924	$	2,235,971
Revenues by Geographic Area Presented by Attributing Revenues to Individual Country	Revenues by geographic area are presented by attributing revenues to the individual country or areas where the services were performed.
		Three Months Ended				Nine Months Ended
		September 30,				September 30,
		2013		2012		2013		2012
		(In thousands)
	United States	$	69,627	$	49,443	$	253,654	$	146,009
	International:
	South America		311,708		360,617		896,029		1,084,210
	Europe/Africa/Mediterranean		185,335		162,324		559,290		484,229
	Australia/Asia		88,054		111,850		333,728		379,240
	Mexico		51,441		44,907		151,223		142,283
	Total revenues	$	706,165	$	729,141	$	2,193,924	$	2,235,971

General_Information_Additional

General Information - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012
	Rigs		Rigs
General Information [Line Items]
Outstanding common stock owned by Loews Corporation	50.40%		50.40%
Period considered to treat short-term, highly liquid investments as cash equivalents			Three months or less
Effect of exchange rate changes on cash balances held in foreign currencies	$0	$0	$0	$0
Recoverable amount of assets held for sale	11,594,000		11,594,000		11,594,000
Amount capitalized for asset replacements and betterments			189,200,000		220,300,000
Number of cold-stacked rigs which were not classified as held for sale	0		0
Senior Notes, current	250,000,000		250,000,000
Current portion of long-term debt	249,935,000		249,935,000
Gain (loss) on foreign currency transactions recognized in income	-4,600,000	-1,900,000	-3,900,000	-900,000
Initial term of contracts minimum months			2 months
Initial term of contracts maximum months			60 months
Minimum [Member]
General Information [Line Items]
Range of rig and equipment project costs, lower limit			25,000		25,000
Estimated useful life for drilling rigs and equipment			3 years
Maximum [Member]
General Information [Line Items]
Range of rig and equipment project costs, upper limit			60,000,000		60,000,000
Estimated useful life for drilling rigs and equipment			30 years
Mid-Water Floaters [Member]
General Information [Line Items]
Number of offshore rigs held for sale	3		3		3
Jack-Ups [Member]
General Information [Line Items]
Number of offshore rigs held for sale	1		1		1
5.15% Senior Notes [Member]
General Information [Line Items]
Interest rate of senior notes	5.15%		5.15%		5.15%
Senior Notes, current maturity date			1-Sep-14
Current portion of long-term debt	$249,935,000		$249,935,000

General_Information_Reconcilia

General Information - Reconciliation of Total Interest Cost to Interest Expense (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Interest Costs Incurred [Abstract]
Total interest cost, including amortization of debt issuance costs	$22,234	$19,145	$71,229	$62,782
Capitalized interest	-20,541	-10,425	-53,516	-26,002
Total interest expense as reported	$1,693	$8,720	$17,713	$36,780

Supplemental_Financial_Informa2

Supplemental Financial Information - Accounts Receivable, Net of Allowance for Doubtful Accounts (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Receivables [Abstract]
Trade receivables	$422,708	$478,987
Value added tax receivables	17,750	13,884
Amounts held in escrow	12,025	11,555
Related party receivables	353	527
Other	124	165
Receivables Gross Current, Total	452,960	505,118
Allowance for bad debts	-28,152	-5,458
Total	$424,808	$499,660

Supplemental_Financial_Informa3

Supplemental Financial Information - Additional Information (Detail) (USD $)	3 Months Ended	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2013
	Customer	Customer
Receivables [Abstract]
Bad debt expense	$22.60	$22.60
Number of customers	2	2

Supplemental_Financial_Informa4

Supplemental Financial Information - Prepaid Expenses and Other Current Assets (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Deferred Costs Capitalized Prepaid And Other Assets Disclosure [Abstract]
Rig spare parts and supplies	$52,195	$57,558
Deferred mobilization costs	23,974	38,074
Prepaid insurance	20,329	12,549
Deferred tax assets	8,619	8,619
Prepaid taxes	25,892	5,950
FOREX contracts	3,272	3,627
Other	7,871	9,722
Total	$142,152	$136,099

Supplemental_Financial_Informa5

Supplemental Financial Information - Accrued Liabilities (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Payables And Accruals [Abstract]
Rig operating expenses	$87,069	$70,078
Payroll and benefits	107,210	88,612
Deferred revenue	34,457	71,699
Accrued capital project/upgrade costs	74,308	56,595
Interest payable	29,422	21,219
Personal injury and other claims	10,065	10,312
FOREX contracts	4,304	29
Other	7,397	5,890
Total	$354,232	$324,434

Supplemental_Financial_Informa6

Supplemental Financial Information - Noncash Investing and Financing Activities (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Condensed Financial Statements, Captions [Line Items]
Accrued but unpaid capital expenditures at period end	$74,308	$48,620
Cash interest payments	54,000	54,187
U.S Federal [Member]
Cash income taxes paid, net of refunds:
Cash income taxes paid, net of refunds	47,000	53,000
Foreign [Member]
Cash income taxes paid, net of refunds:
Cash income taxes paid, net of refunds	62,951	56,070
State [Member]
Cash income taxes paid, net of refunds:
Cash income taxes paid, net of refunds	$190	$212

Supplemental_Financial_Informa7

Supplemental Financial Information - Noncash Investing and Financing Activities (Parenthetical) (Detail) (USD $)	9 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012
Supplemental Cash Flow Information [Abstract]
Interest Paid, Net	$8.90	$31.90
Interest on Internal Revenue Service Assessment		$0.20

Earnings_Per_Share_Reconciliat

Earnings Per Share - Reconciliation of Numerators and Denominators of Basic and Diluted Per-Share Computations (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, except Per Share data, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Earnings Per Share [Abstract]
Net income - basic and diluted numerator:	$94,748	$178,186	$456,071	$564,816
Weighted average shares - basic (denominator):	139,035	139,030	139,034	139,029
Effect of dilutive potential shares
Stock options and stock appreciation rights	30	23	38	17
Total weighted-average shares outstanding	139,065	139,053	139,072	139,046
Earnings per share:
Basic	$0.68	$1.28	$3.28	$4.06
Diluted	$0.68	$1.28	$3.28	$4.06

Earnings_Per_Share_Securities_

Earnings Per Share - Securities Excluded from Computation of Diluted Earning Per Share (Detail)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Stock options [Member]
Employee and director:
Securities excluded from computation of diluted earning per share	18	18	18	18
Stock appreciation rights [Member]
Employee and director:
Securities excluded from computation of diluted earning per share	982	874	885	900

Marketable_Securities_Investme

Marketable Securities - Investments in Marketable Securities as Available for Sale (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$800,193	$1,149,983
Unrealized Gain (Loss)	11	175
Market Value	800,204	1,150,158
U.S. Treasury Bills and Notes (due within one year) [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	799,981	1,149,707
Unrealized Gain (Loss)	-1	150
Market Value	799,980	1,149,857
Mortgage-backed securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	212	276
Unrealized Gain (Loss)	12	25
Market Value	$224	$301

Marketable_Securities_Summary_

Marketable Securities - Summary of Proceeds from Sales and Maturities of Marketable Securities and Gross Realized Gains and Losses (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Investments Debt And Equity Securities [Abstract]
Proceeds from maturities	$1,475,000	$675,000	$3,225,000	$1,925,000
Proceeds from sales	25	56	62	150,106
Gross realized gains
Gross realized losses	($1)	($1)	($1)	($6)

Derivative_Financial_Instrumen2

Derivative Financial Instruments - Additional Information (Detail)

9 Months Ended

3 Months Ended

9 Months Ended

In Millions, unless otherwise specified

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2012

Sep. 30, 2013

Sep. 30, 2012

USD ($)

USD ($)

AUD

BRL

GBP (£)

MXN

NOK

FOREX contracts [Member]

Reclassification out of Accumulated Other Comprehensive Income [Member]

Reclassification out of Accumulated Other Comprehensive Income [Member]

Reclassification out of Accumulated Other Comprehensive Income [Member]

Reclassification out of Accumulated Other Comprehensive Income [Member]

Counterparty

USD ($)

USD ($)

USD ($)

USD ($)

Derivative Instruments And Hedging Activities [Line Items]

Notional amount of foreign currency contracts settled

$233.90

$236.30

FOREX contracts outstanding in the aggregate notional amount

151.6

20.7

86.7

20.5

11.7

12

Number of counterparties to FOREX contracts

2

Net unrealized gains (losses) associated with FOREX contracts to be reclassified to earnings

-1

Amount reclassified from AOCGL due to the probability of a forecasted transaction not occurring

$0

$0

$0

$0

Derivative_Financial_Instrumen3

Derivative Financial Instruments - Amounts Recognized in our Consolidated Statements of Operations Related to our FOREX Contracts Designated as Accounting Hedges (Detail) (Contract drilling expense [Member], Designated as hedging instrument [Member], USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Contract drilling expense [Member] | Designated as hedging instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in Income	($5,018)	($2,715)	($2,246)	($5,692)

Derivative_Financial_Instrumen4

Derivative Financial Instruments - Fair Values of our Derivative Financial Instruments (Detail) (FOREX contracts [Member], USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Accrued liabilities [Member]
Derivatives, Fair Value [Line Items]
Derivative liabilities designated as hedging instruments, current	($4,304)	($29)
Prepaid expenses and other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivative assets designated as hedging instruments, current	$3,272	$3,627

Derivative_Financial_Instrumen5

Derivative Financial Instruments - Recognized in our Consolidated Balance Sheets and Consolidated Statements of Operations Related to our FOREX Contracts Designated as Cash Flow Hedges (Detail) (FOREX contracts [Member], Derivative designated as accounting hedges [Member], USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in AOCGL on derivative (effective portion)	$2,486	$1,720	($7,539)	$6,191
Contract drilling expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of loss reclassified from AOCGL into income (effective portion)	-5,572	-2,873	-2,951	-5,300
Foreign currency transaction gain (loss) [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of gain (loss) recognized in income on derivative (ineffective portion and amount excluded from effectiveness testing)	$59		($59)	($39)

Financial_Instruments_and_Fair2

Financial Instruments and Fair Value Disclosures - Additional Information (Detail) (USD $)

3 Months Ended

9 Months Ended

12 Months Ended

3 Months Ended

9 Months Ended

12 Months Ended

Sep. 30, 2013

Sep. 30, 2013

Sep. 30, 2012

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Dec. 31, 2012

Sep. 30, 2013

Sep. 30, 2013

Dec. 31, 2012

Dec. 31, 2012

Sep. 30, 2013

Sep. 30, 2013

Dec. 31, 2012

Dec. 31, 2012

Customer

Customer

5.70% Senior Notes [Member]

5.70% Senior Notes [Member]

5.875% Senior Notes [Member]

5.875% Senior Notes [Member]

4.875% Senior Notes [Member]

4.875% Senior Notes [Member]

5.15% Senior Notes [Member]

5.15% Senior Notes [Member]

Level 1 [Member]

Level 1 [Member]

Level 1 [Member]

Level 1 [Member]

Level 1 [Member]

Net Profits Interest [Member]

Ogx and Niko Resources [Member]

Accounts Receivable [Member]

Accounts Receivable [Member]

Accounts Receivable [Member]

Cash Held in Money Market Funds [Member]

Cash Held in Money Market Funds [Member]

Time Deposits [Member]

U.S. Treasury Bills [Member]

U.S. Treasury Bills [Member]

Customer

Petroleo Brasileiro S.A. [Member]

Petroleo Brasileiro S.A. [Member]

OGX Petroleo e Gas Ltda [Member]

Customer Concentration Risk [Member]

Customer Concentration Risk [Member]

Customer Concentration Risk [Member]

Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]

Accounts receivable due from major customer

$424,808,000

$424,808,000

$499,660,000

$17,200,000

$120,400,000

$116,400,000

$80,300,000

Percentage of accounts receivable due from major customer

28.00%

24.00%

17.00%

Number of customers

2

2

2

Allowance for bad debts

28,152,000

28,152,000

5,458,000

Bad debt expense

22,600,000

22,600,000

22,600,000

Net profits interest percent

27.00%

Fair value of investments

385,600,000

284,900,000

20,000,000

800,000,000

1,149,900,000

Transfers between fair value levels

$0

$0

Interest rate of senior notes

5.70%

5.70%

5.88%

5.88%

4.88%

4.88%

5.15%

5.15%

Financial_Instruments_and_Fair3

Financial Instruments and Fair Value Disclosures - Assets and Liabilities Measured at Fair Value on Recurring and Nonrecurring Basis (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Fair Value, Measurements, Nonrecurring [Member]
Assets:
Assets held for sale	$3,900	$3,900
Fair Value Measurements, Recurring [Member]
Assets:
Short-term investments	1,205,626	1,434,751
FOREX contracts	3,272	3,627
Mortgage-backed securities	224	301
Total assets	1,209,122	1,438,679
Liabilities:
FOREX contracts	-4,304	-29
Level 1 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets:
Assets held for sale
Level 1 [Member] | Fair Value Measurements, Recurring [Member]
Assets:
Short-term investments	1,205,626	1,434,751
FOREX contracts
Mortgage-backed securities
Total assets	1,205,626	1,434,751
Liabilities:
FOREX contracts
Level 2 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets:
Assets held for sale
Level 2 [Member] | Fair Value Measurements, Recurring [Member]
Assets:
Short-term investments
FOREX contracts	3,272	3,627
Mortgage-backed securities	224	301
Total assets	3,496	3,928
Liabilities:
FOREX contracts	-4,304	-29
Level 3 [Member] | Fair Value, Measurements, Nonrecurring [Member]
Assets:
Assets held for sale	3,900	3,900
Level 3 [Member] | Fair Value Measurements, Recurring [Member]
Assets:
Short-term investments
FOREX contracts
Mortgage-backed securities
Total assets
Liabilities:
FOREX contracts

Financial_Instruments_and_Fair4

Financial Instruments and Fair Value Disclosures - Fair Value and Related Carrying Values of Our Debt Instruments (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Millions, unless otherwise specified
4.875% Senior Notes [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	$268.10	$275.50
4.875% Senior Notes [Member] | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	249.9	249.8
5.15% Senior Notes [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	260	269
5.15% Senior Notes [Member] | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	249.9	249.9
5.70% Senior Notes [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	567.9	641.4
5.70% Senior Notes [Member] | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	496.9	496.9
5.875% Senior Notes [Member] | Fair Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Fair Value	587.1	617.1
5.875% Senior Notes [Member] | Carrying Value [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Carrying Value	$499.50	$499.50

Financial_Instruments_and_Fair5

Financial Instruments and Fair Value Disclosures - Fair Value and Related Carrying Values of Our Debt Instruments (Parenthetical) (Detail)	Sep. 30, 2013	Dec. 31, 2012
4.875% Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate of senior notes	4.88%	4.88%
5.15% Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate of senior notes	5.15%	5.15%
5.70% Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate of senior notes	5.70%	5.70%
5.875% Senior Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Interest rate of senior notes	5.88%	5.88%

Drilling_and_Other_Property_an2

Drilling and Other Property and Equipment - Summary of Cost and Accumulated Depreciation of Drilling and Other Property and Equipment (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Property, Plant and Equipment [Line Items]
Property and equipment	$8,979,647	$8,222,778
Less: accumulated depreciation	-3,648,177	-3,357,806
Drilling and other property and equipment, net	5,331,470	4,864,972
Drilling rigs and equipment [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	7,295,964	7,107,279
Construction work-in-progress [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	1,553,430	990,964
Land and buildings [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	65,362	64,296
Office equipment and other [Member]
Property, Plant and Equipment [Line Items]
Property and equipment	$64,891	$60,239

Drilling_and_Other_Property_an3

Drilling and Other Property and Equipment - Summary of Construction Work-in-Progress, Including Capitalized Interest (Detail) (USD $)	Sep. 30, 2013	Dec. 31, 2012
In Thousands, unless otherwise specified
Property, Plant and Equipment [Line Items]
Rig(s) Under Construction	$1,553,430	$990,964
Ultra-deepwater drillships [Member]
Property, Plant and Equipment [Line Items]
Rig(s) Under Construction	834,476	741,059
Ocean Great White [Member] | Ultra-deepwater semisubmersible [Member]
Property, Plant and Equipment [Line Items]
Rig(s) Under Construction	192,311
Ocean Onyx [Member] | Deepwater semisubmersibles [Member]
Property, Plant and Equipment [Line Items]
Rig(s) Under Construction	299,886	167,403
Ocean Apex [Member] | Deepwater semisubmersibles [Member]
Property, Plant and Equipment [Line Items]
Rig(s) Under Construction	$226,757	$82,502

Commitments_and_Contingencies_

Commitments and Contingencies - Additional Information (Detail) (USD $)	9 Months Ended	12 Months Ended
In Millions, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
	Installment
Schedule Of Commitments And Contingencies [Line Items]
Deductible for marine liability coverage including personal injury claims, per first occurrence	$10
Range of deductible for liability coverage for personal injury claims, lower limit	5
Range of deductible for liability coverage for personal injury claims, upper limit	100
Other purchase obligations	0	0
Contingent liability under letters of credit and other bonds	70.2
Collateral deposits related to agreements	58.2
Personal Injury Claims [Member]
Schedule Of Commitments And Contingencies [Line Items]
Personal injury claims recorded	35.5	36.1
Personal Injury Claims [Member] | Accrued Liabilities [Member]
Schedule Of Commitments And Contingencies [Line Items]
Personal injury claims recorded	8.1	9.9
Personal Injury Claims [Member] | Other Liabilities [Member]
Schedule Of Commitments And Contingencies [Line Items]
Personal injury claims recorded	27.4	26.2
Keppel AmFELS LLC [Member]
Schedule Of Commitments And Contingencies [Line Items]
Cost of enhancement of project	335
Expected amount of second installments payable in next 12 months	21.9
Number of installments due under each rig construction agreement	11
Number of installments paid	9
Vessel modification agreement Payment during the period	58.4	65.7
Hyundai Heavy Industries Co Ltd [Member] | UltraDeepwater Floater Rig [Member]
Schedule Of Commitments And Contingencies [Line Items]
Water depth of rig	10,000
Cost of enhancement of project	755
Total number of installments due under each turnkey construction agreements	2
Cost of construction per shipyard agreement	628.5
First installment for Ultra-Deep water Floater Construction	188.6
Final installment for Ultra-Deep water Floater Construction	439.9
Hyundai Heavy Industries Co Ltd [Member] | Ultra-deepwater drillships [Member]
Schedule Of Commitments And Contingencies [Line Items]
Cost of enhancement of project	2,600
Total number of installments due under each turnkey construction agreements	2
Number of turnkey contracts for drill ship construction	4
First Installments on Drill ships aggregate amount for Drill ship Construction	647.6
Hyundai Heavy Industries Co Ltd [Member] | Ultra-deepwater drillships [Member] | First Quarter 2014 [Member]
Schedule Of Commitments And Contingencies [Line Items]
Expected amount of second installments payable in next 12 months	394
Hyundai Heavy Industries Co Ltd [Member] | Ultra-deepwater drillships [Member] | Fourth Quarter of 2013 [Member]
Schedule Of Commitments And Contingencies [Line Items]
Expected amount of second installments payable in next 12 months	394
Hyundai Heavy Industries Co Ltd [Member] | Ultra-deepwater drillships [Member] | Second Quarter of 2014 [Member]
Schedule Of Commitments And Contingencies [Line Items]
Expected amount of second installments payable in next 12 months	395
Hyundai Heavy Industries Co Ltd [Member] | Ultra-deepwater drillships [Member] | Fourth Quarter of 2014 [Member]
Schedule Of Commitments And Contingencies [Line Items]
Expected amount of second installments payable in second year	395
Jurong Shipyard Pte Ltd [Member]
Schedule Of Commitments And Contingencies [Line Items]
Cost of enhancement of project	370
Number of installments due under each rig construction agreement	12
Number of installments paid	5
Vessel modification agreement Payment during the period	33.8	27
Construction agreement balance amount payable	74.3
Keppel FELS Limited [Member]
Schedule Of Commitments And Contingencies [Line Items]
Cost of enhancement of project	120
Cost of construction per shipyard agreement	29
Number of installments due under each rig construction agreement	7
Number of installments paid	2
Vessel modification agreement Payment during the period	10.1
Construction agreement balance amount payable	$18.80

Accumulated_Other_Comprehensiv2

Accumulated Other Comprehensive Gain (Loss) - Components of Accumulated Other Comprehensive Gain Loss (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$2,496
Change in other comprehensive gain (loss) before reclassifications, after tax of $2,638 and $6	-4,894
Reclassification adjustments for items included in Net Income, after tax of $(1,033) and $19	1,772
Ending balance	-626
FOREX Contracts [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	2,350
Change in other comprehensive gain (loss) before reclassifications, after tax of $2,638 and $6	-4,901
Reclassification adjustments for items included in Net Income, after tax of $(1,033) and $19	1,918
Ending balance	-633
Marketable Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	146
Change in other comprehensive gain (loss) before reclassifications, after tax of $2,638 and $6	7
Reclassification adjustments for items included in Net Income, after tax of $(1,033) and $19	-146
Ending balance	$7

Accumulated_Other_Comprehensiv3

Accumulated Other Comprehensive Gain (Loss) - Components of Accumulated Other Comprehensive Gain Loss (Parenthetical) (Detail) (USD $)	9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013
Amounts Reclassified Out Of Accumulated Other Comprehensive Income Loss [Abstract]
Change in other comprehensive gain (loss), tax	$2,638
Change in other comprehensive gain (loss), tax	6
Reclassification adjustments for items included in Net Income, tax	-1,033
Reclassification adjustments for items included in Net Income, tax	$19

Accumulated_Other_Comprehensiv4

Accumulated Other Comprehensive Gain (Loss) - Changes in Accumulated Other Comprehensive Income Loss (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Contract drilling, excluding depreciation	$419,488	$357,281	$1,163,618	$1,159,635
Other, net	-326	168	-746	767
Income tax expense	36,817	56,661	137,974	168,224
Net of tax	-94,748	-178,186	-456,071	-564,816
Reclassification out of Accumulated Other Comprehensive Income [Member] | Marketable Securities [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other, net	-15		-165
Income tax expense	1		19
Net of tax	-14		-146
FOREX contracts [Member] | Reclassification out of Accumulated Other Comprehensive Income [Member] | Cash Flow Hedges [Member]
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Contract drilling, excluding depreciation	5,572		2,951
Income tax expense	-1,950		-1,033
Net of tax	$3,622		$1,918

Segments_and_Geographic_Area_A2

Segments and Geographic Area Analysis - Additional Information (Detail)	9 Months Ended
	Sep. 30, 2013
	Segment
	Country
Segment Reporting [Abstract]
Number of reportable segments	1
Number of countries with rigs	13

Segments_and_Geographic_Area_A3

Segments and Geographic Area Analysis - Revenues from Contract Drilling Services by Equipment Type (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Segment Reporting Information [Line Items]
Contract drilling	$690,741	$714,027	$2,135,612	$2,195,443
Revenues related to reimbursable expenses	15,424	15,114	58,312	40,528
Total revenues	706,165	729,141	2,193,924	2,235,971
Ultra-deepwater semisubmersible [Member]
Segment Reporting Information [Line Items]
Contract drilling	195,215	195,574	617,673	673,233
Deepwater [Member]
Segment Reporting Information [Line Items]
Contract drilling	147,333	163,816	495,858	452,384
Mid-Water [Member]
Segment Reporting Information [Line Items]
Contract drilling	297,368	319,491	891,449	948,548
Total Floaters [Member]
Segment Reporting Information [Line Items]
Contract drilling	639,916	678,881	2,004,980	2,074,165
Jack-Ups [Member]
Segment Reporting Information [Line Items]
Contract drilling	$50,825	$35,146	$130,632	$121,278

Segments_and_Geographic_Area_A4

Segments and Geographic Area Analysis - Revenues by Geographic Area Presented by Attributing Revenues to Individual Country (Detail) (USD $)	3 Months Ended		9 Months Ended
In Thousands, unless otherwise specified	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	$706,165	$729,141	$2,193,924	$2,235,971
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	69,627	49,443	253,654	146,009
South America [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	311,708	360,617	896,029	1,084,210
Europe/Africa/Mediterranean [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	185,335	162,324	559,290	484,229
Australia/Asia [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	88,054	111,850	333,728	379,240
Mexico [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Total revenues	$51,441	$44,907	$151,223	$142,283

Income_Taxes_Additional_Inform

Income Taxes - Additional Information (Detail) (USD $)	3 Months Ended	9 Months Ended	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Sep. 30, 2013	Sep. 30, 2013
		Mexico [Member]	Mexico [Member]	Mexico [Member]	Mexico [Member]
			2007 Tax year [Member]	2004 Tax Year [Member]	2006 Tax Year [Member]
Income Taxes [Line Items]
Tax expense increase (decrease)	($27.50)
Total tax assessment including interest and penalty				22.9	24.4
Net cash cost on settlement of tax liability		3.7
Increase in uncertain tax position due to tax settlement		13.2
Change in interest on uncertain tax positions		5
Change in penalties on uncertain tax positions		2.7
Reduction in uncertain tax positions related to statute of limitations expirations			4.3
Reversal of accrued interest on uncertain tax position			1.5
Reversal of accrued penalty on uncertain tax position			$0.60