CONSOLIDATED STATEMENT OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	$ (113,891)	$ 104,468	$ 279,773
Adjustments to reconcile net income (loss) to cash provided by operating activities:
Depreciation, depletion and amortization	622,211	632,760	651,052
Impairment of oil and gas properties	114,875	771,037	0
Deferred income tax expense (benefit)	(72,968)	(112,567)	138,380
(Gain) loss on sale of assets	(3,866)	(17,120)	(21,351)
Exploratory dry hole cost	3,452	7,907	808
(Gain) loss on derivative instruments	(56,686)	(219,319)	0
Net cash received (paid) in settlement of derivative instruments	194,289	81,716	0
Earnings of equity method investments	(6,415)	(3,080)	(1,102)
Amortization of debt issuance costs	4,454	4,754	3,693
Stock-based compensation and other	13,645	21,429	46,965
Changes in assets and liabilities:
Accounts receivable, net	112,406	(11,689)	(49,398)
Income taxes	(711)	(34,282)	29,002
Inventories	(3,023)	3,441	(3,033)
Other current assets	(817)	733	(428)
Accounts payable and accrued liabilities	(64,533)	2,883	(22,908)
Other assets and liabilities	(1,685)	1,989	(8,014)
Stock-based compensation tax benefit	0	1,375	(18,913)
Net cash provided by operating activities	740,737	1,236,435	1,024,526
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(955,602)	(1,479,632)	(1,194,739)
Acquisitions	(16,312)	(214,737)	0
Proceeds from sale of assets	7,653	39,492	323,501
Restricted cash	0	28,094	(28,094)
Investment in equity method investments	(29,073)	(38,057)	(18,875)
Net cash used in investing activities	(993,334)	(1,664,840)	(918,207)
CASH FLOWS FROM FINANCING ACTIVITIES
Borrowings from debt	877,000	2,032,000	955,000
Repayments of debt	(604,000)	(1,427,000)	(895,000)
Treasury stock repurchases	0	(138,852)	(164,634)
Dividends paid	(33,090)	(33,278)	(25,232)
Stock-based compensation tax benefit	0	(1,375)	18,913
Capitalized debt issuance costs	(7,838)	(5,626)	(2,750)
Other	85	90	48
Net cash provided by (used in) financing activities	232,157	425,959	(113,655)
Net decrease in cash and cash equivalents	(20,440)	(2,446)	(7,336)
Cash and cash equivalents, beginning of period	20,954	23,400	30,736
Cash and cash equivalents, end of period	$ 514	$ 20,954	$ 23,400