CONSOLIDATED STATEMENT OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	$ 100,393	$ (417,124)	$ (113,891)
Adjustments to reconcile net income (loss) to cash provided by operating activities:
Depreciation, depletion and amortization	568,817	590,128	622,211
Impairment of oil and gas properties and other assets	482,811	435,619	114,875
Deferred income tax benefit	(321,113)	(230,707)	(72,968)
(Gain) loss on sale of assets	11,565	1,857	(3,866)
Exploratory dry hole cost	3,820	10,120	3,452
(Gain) loss on derivative instruments	(16,926)	38,950	(56,686)
Net cash received (paid) in settlement of derivative instruments	8,056	(1,682)	194,289
(Earnings) loss on equity method investments	100,486	2,477	(6,415)
Amortization of debt issuance costs	4,774	5,083	4,454
Stock-based compensation and other	33,419	25,982	13,645
Changes in assets and liabilities:
Accounts receivable, net	(25,036)	(71,060)	112,406
Income taxes	(46,368)	(5,975)	(711)
Inventories	1,334	3,044	(3,023)
Other current assets	(104)	(21)	(817)
Accounts payable and accrued liabilities	(2,552)	10,858	(55,217)
Interest payable	(75)	(2,573)	(455)
Other assets and liabilities	(5,141)	2,465	(1,685)
Net cash provided by operating activities	898,160	397,441	749,598
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(764,558)	(375,153)	(955,602)
Acquisitions	0	0	(16,312)
Proceeds from sale of assets	115,444	50,419	7,653
Investment in equity method investments	(57,039)	(28,484)	(29,073)
Net cash used in investing activities	(706,153)	(353,218)	(993,334)
CASH FLOWS FROM FINANCING ACTIVITIES
Borrowings from debt	0	90,000	877,000
Repayments of debt	0	(587,000)	(604,000)
Treasury stock repurchases	(123,741)	0	0
Sale of common stock, net	0	995,279	0
Dividends paid	(78,838)	(36,187)	(33,090)
Tax withholding on vesting of stock awards	(7,973)	(5,064)	(8,861)
Capitalized debt issuance costs	0	(3,223)	(7,838)
Other	50	0	85
Net cash (used in) provided by financing activities	(210,502)	453,805	223,296
Net (decrease) increase in cash and cash equivalents	(18,495)	498,028	(20,440)
Cash and cash equivalents, beginning of period	498,542	514	20,954
Cash and cash equivalents, end of period	$ 480,047	$ 498,542	$ 514