Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 347,011	$ 335,432
Marketable securities	1,750,053	1,150,158
Accounts receivable, net of allowance for bad debts	469,355	499,660
Prepaid expenses and other current assets	143,997	136,099
Assets held for sale	7,694	11,594
Total current assets	2,718,110	2,132,943
Drilling and other property and equipment, net of accumulated depreciation	5,467,227	4,864,972
Other assets	206,097	237,371
Total assets	8,391,434	7,235,286
Current liabilities:
Accounts payable	94,151	96,631
Accrued liabilities	370,671	324,434
Taxes payable	30,806	64,481
Current portion of long-term debt	249,954
Total current liabilities	745,582	485,546
Long-term debt	2,244,189	1,496,066
Deferred tax liability	525,541	490,946
Other liabilities	238,864	186,334
Total liabilities	3,754,176	2,658,892
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; 143,952,248 shares issued and 139,035,448 shares outstanding at December 31, 2013; 143,948,370 shares issued and 139,031,570 shares outstanding at December 31, 2012)	1,440	1,439
Additional paid-in capital	1,988,720	1,983,957
Retained earnings	2,761,161	2,702,915
Accumulated other comprehensive gain (loss)	350	2,496
Treasury stock, at cost (4,916,800 shares of common stock at December 31, 2013 and 2012)	(114,413)	(114,413)
Total stockholders' equity	4,637,258	4,576,394
Total liabilities and stockholders' equity	$ 8,391,434	$ 7,235,286