CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Operating activities:
Net income	$ 720,477	$ 962,542	$ 955,457
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	392,913	398,612	393,177
Impairment of assets	62,437
Gain on disposition of assets	(80,844)	(4,758)	(34,714)
Loss (gain) on foreign currency forward exchange contracts	4,302	(7,206)	(3,307)
Deferred tax provision	(51,472)	2,141	(6,916)
Accretion of discounts on marketable securities	4,622	1,586	(648)
Stock-based compensation expense	4,357	4,956	5,928
Deferred income, net	1,767	(32,219)	17,777
Deferred expenses, net	67,824	53,317	(59,208)
Long-term employee remuneration programs	7,611	3,944	3,140
Other assets, noncurrent	(2,794)	2,220	2,477
Other liabilities, noncurrent	3,614	6,921	7,801
(Payments of) proceeds from settlement of foreign currency forward exchange contracts designated as accounting hedges	(4,302)	7,206	3,307
Other	1,258	319	1,166
Changes in operating assets and liabilities:
Accounts receivable	64,056	60,785	143,096
Prepaid expenses and other current assets	(8,960)	(6,406)	1,519
Accounts payable and accrued liabilities	10,354	(9,842)	33,326
Taxes payable	114,049	(24,013)	(181,060)
Net cash provided by operating activities	1,311,269	1,420,105	1,282,318
Investing activities:
Capital expenditures (including rig construction)	(702,041)	(774,756)	(434,262)
Proceeds from disposition of assets, net of disposal costs	138,495	5,603	188,066
Proceeds from sale and maturities of marketable securities	2,725,118	5,362,138	5,450,230
Purchases of marketable securities	(2,977,290)	(5,653,665)	(5,660,518)
Net cash used in investing activities	(815,718)	(1,060,680)	(456,484)
Financing activities:
Redemption of zero coupon debentures			(4,238)
Debt issuance costs and arrangement fees	(3,838)		(98)
Payment of dividends	(490,245)	(490,057)	(733,661)
Other	199	4	139
Net cash used in financing activities	(493,884)	(490,053)	(737,858)
Net change in cash and cash equivalents	1,667	(130,628)	87,976
Cash and cash equivalents, beginning of year	333,765	464,393	376,417
Cash and cash equivalents, end of year	$ 335,432	$ 333,765	$ 464,393