Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 376,359	$ 333,765
Marketable securities	975,947	902,414
Accounts receivable, net of allowance for bad debts	532,302	563,934
Prepaid expenses and other current assets	160,012	192,570
Total current assets	2,044,620	1,992,683
Drilling and other property and equipment, net of accumulated depreciation	4,780,747	4,667,469
Other assets	257,530	304,005
Total assets	7,082,897	6,964,157
Current liabilities:
Accounts payable	63,953	64,147
Accrued liabilities	303,718	336,400
Taxes payable	24,787	26,744
Total current liabilities	392,458	427,291
Long-term debt	1,495,943	1,495,823
Deferred tax liability	535,965	536,815
Other liabilities	176,539	171,165
Total liabilities	2,600,905	2,631,094
Commitments and contingencies (Note 8)
Stockholders' equity:
Common stock (par value $0.01, 500,000,000 shares authorized; 143,946,586 shares issued and 139,029,786 shares outstanding at June 30, 2012; 143,944,009 shares issued and 139,027,209 shares outstanding at December 31, 2011)	1,439	1,439
Additional paid-in capital	1,980,980	1,978,369
Retained earnings	2,614,072	2,472,310
Accumulated other comprehensive gain (loss)	(86)	(4,642)
Treasury stock, at cost (4,916,800 shares at June 30, 2012 and December 31, 2011)	(114,413)	(114,413)
Total stockholders' equity	4,481,992	4,333,063
Total liabilities and stockholders' equity	$ 7,082,897	$ 6,964,157