Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010
Current assets:
Cash and cash equivalents	$ 333,765	$ 464,393
Marketable securities	902,414	612,346
Accounts receivable, net of allowance for bad debts	563,934	609,606
Prepaid expenses and other current assets	192,570	177,153
Total current assets	1,992,683	1,863,498
Drilling and other property and equipment, net of accumulated depreciation	4,667,469	4,283,792
Long-term receivable	0	35,361
Other assets	304,005	544,333
Total assets	6,964,157	6,726,984
Current liabilities:
Accounts payable	64,147	99,236
Accrued liabilities	336,400	469,190
Taxes payable	26,744	57,862
Total current liabilities	427,291	626,288
Long-term debt	1,495,823	1,495,593
Deferred tax liability	536,815	542,258
Other liabilities	171,165	201,133
Total liabilities	2,631,094	2,865,272
Commitments and contingencies (Note 11)
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; 143,944,009 shares issued and 139,027,209 shares outstanding at December 31, 2011; 143,943,624 shares issued and 139,026,824 shares outstanding at December 31, 2010)	1,439	1,439
Additional paid-in capital	1,978,369	1,972,550
Retained earnings	2,472,310	1,998,995
Accumulated other comprehensive gain (loss)	(4,642)	3,141
Treasury stock, at cost (4,916,800 shares at December 31, 2011 and 2010)	(114,413)	(114,413)
Total stockholders' equity	4,333,063	3,861,712
Total liabilities and stockholders' equity	$ 6,964,157	$ 6,726,984