Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 123,521	$ 333,765
Marketable securities	1,276,592	902,414
Accounts receivable, net of allowance for bad debts	574,906	563,934
Prepaid expenses and other current assets	134,682	192,570
Assets held for sale	22,223
Total current assets	2,131,924	1,992,683
Drilling and other property and equipment, net of accumulated depreciation	4,611,233	4,667,469
Other assets	282,381	304,005
Total assets	7,025,538	6,964,157
Current liabilities:
Accounts payable	59,460	64,147
Accrued liabilities	306,975	336,400
Taxes payable	43,259	26,744
Total current liabilities	409,694	427,291
Long-term debt	1,495,883	1,495,823
Deferred tax liability	538,980	536,815
Other liabilities	178,432	171,165
Total liabilities	2,622,989	2,631,094
Commitments and contingencies (Note 8)
Stockholders' equity:
Common stock (par value $0.01, 500,000,000 shares authorized; 143,944,709 shares issued and 139,027,909 shares outstanding at March 31, 2012; 143,944,009 shares issued and 139,027,209 shares outstanding at December 31, 2011)	1,439	1,439
Additional paid-in capital	1,979,636	1,978,369
Retained earnings	2,535,071	2,472,310
Accumulated other comprehensive gain (loss)	816	(4,642)
Treasury stock, at cost (4,916,800 shares at March 31, 2012 and December 31, 2011)	(114,413)	(114,413)
Total stockholders' equity	4,402,549	4,333,063
Total liabilities and stockholders' equity	$ 7,025,538	$ 6,964,157