Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Operating activities:
Net income	$ 962,542	$ 955,457	$ 1,376,219
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	398,612	393,177	346,446
Gain on disposition of assets	(4,758)	(34,714)	(7,902)
Loss (gain) on sale of marketable securities, net	(779)	7	(619)
(Gain) loss on foreign currency forward exchange contracts	(7,206)	(3,307)	(17,751)
Deferred tax provision	2,141	(6,916)	85,524
Accretion of discounts on marketable securities	1,586	(648)	(679)
Amortization/write-off of debt issuance costs	868	882	672
Amortization of debt discounts	230	277	299
Stock-based compensation expense	4,956	5,928	6,440
Excess tax benefits from stock-based payment arrangements			(99)
Deferred income, net	(32,219)	17,777	37,405
Deferred expenses, net	53,317	(59,208)	(46,640)
Other assets, noncurrent	2,220	2,477	(2,775)
Other liabilities, noncurrent	10,865	10,941	17,448
Proceeds from settlement of foreign currency forward exchange contracts designated as accounting hedges	7,206	3,307	8,895
Changes in operating assets and liabilities:
Accounts receivable	60,785	143,096	(219,867)
Prepaid expenses and other current assets	(6,406)	1,519	3,503
Accounts payable and accrued liabilities	(9,842)	33,326	(26,698)
Taxes payable	(24,013)	(181,060)	(43,007)
Net cash provided by operating activities	1,420,105	1,282,318	1,516,814
Investing activities:
Capital expenditures (including rig construction)	(774,756)	(434,262)	(412,444)
Rig Acquisitions			(950,024)
Proceeds from disposition of assets, net of disposal costs	5,603	188,066	40,462
Proceeds from sale and maturities of marketable securities	5,362,138	5,450,230	4,473,891
Purchases of marketable securities	(5,653,665)	(5,660,518)	(4,473,575)
Cost to settle foreign currency forward exchange contracts not designated as accounting hedges			(28,445)
Net cash used in investing activities	(1,060,680)	(456,484)	(1,350,135)
Financing activities:
Redemption of zero coupon debentures		(4,238)
Issuance of 5.875% senior unsecured notes			499,255
Issuance of 5.70% senior unsecured notes			496,720
Debt issuance costs and arrangement fees		(98)	(8,671)
Payment of dividends	(490,057)	(733,661)	(1,115,211)
Other	4	139	1,593
Net cash used in financing activities	(490,053)	(737,858)	(126,314)
Net change in cash and cash equivalents	(130,628)	87,976	40,365
Cash and cash equivalents, beginning of year	464,393	376,417	336,052
Cash and cash equivalents, end of year	$ 333,765	$ 464,393	$ 376,417