CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 335,432	$ 333,765
Marketable securities	1,150,158	902,414
Accounts receivable, net of allowance for bad debts	499,660	563,934
Prepaid expenses and other current assets	136,099	192,570
Assets held for sale	11,594
Total current assets	2,132,943	1,992,683
Drilling and other property and equipment, net of accumulated depreciation	4,864,972	4,667,469
Other assets	237,371	304,005
Total assets	7,235,286	6,964,157
Current liabilities:
Accounts payable	96,631	64,147
Accrued liabilities	324,434	336,400
Taxes payable	64,481	26,744
Total current liabilities	485,546	427,291
Long-term debt	1,496,066	1,495,823
Deferred tax liability	490,946	536,815
Other liabilities	186,334	171,165
Total liabilities	2,658,892	2,631,094
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; 143,948,370 shares issued and 139,031,570 shares outstanding at December 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	1,983,957	1,978,369
Retained earnings	2,702,915	2,472,310
Accumulated other comprehensive gain (loss)	2,496	(4,642)
Treasury stock, at cost (4,916,800 shares of common stock at December 31, 2012 and 2011)	(114,413)	(114,413)
Total stockholders' equity	4,576,394	4,333,063
Total liabilities and stockholders' equity	$ 7,235,286	$ 6,964,157