Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 438,794	$ 335,432
Marketable securities	800,204	1,150,158
Accounts receivable, net of allowance for bad debts	424,808	499,660
Prepaid expenses and other current assets	142,152	136,099
Assets held for sale	11,594	11,594
Total current assets	1,817,552	2,132,943
Drilling and other property and equipment, net of accumulated depreciation	5,331,470	4,864,972
Other assets	193,586	237,371
Total assets	7,342,608	7,235,286
Current liabilities:
Accounts payable	86,533	96,631
Accrued liabilities	354,232	324,434
Taxes payable	26,175	64,481
Current portion of long-term debt	249,935
Total current liabilities	716,875	485,546
Long-term debt	1,246,321	1,496,066
Deferred tax liability	532,729	490,946
Other liabilities	182,347	186,334
Total liabilities	2,678,272	2,658,892
Commitments and contingencies (Note 8)
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 September 30, 2013; 143,948,370 shares issued and 139,031,570 shares outstanding at December 31, 2012)	1,440	1,439
Additional paid-in capital	1,986,693	1,983,957
Retained earnings	2,791,242	2,702,915
Accumulated other comprehensive gain (loss)	(626)	2,496
Treasury stock, at cost (4,916,800 shares of common stock at September 30, 2013 and December 31, 2012)	(114,413)	(114,413)
Total stockholders' equity	4,664,336	4,576,394
Total liabilities and stockholders' equity	$ 7,342,608	$ 7,235,286