CONSOLIDATED STATEMENT OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	$ 557,043	$ 100,393	$ (417,124)
Adjustments to reconcile net income (loss) to cash provided by operating activities:
Depreciation, depletion and amortization	417,479	568,817	590,128
Impairment of oil and gas properties	0	482,811	435,619
Deferred income tax expense (benefit)	229,603	(321,113)	(230,707)
Loss on sale of assets	16,327	11,565	1,857
Exploratory dry hole cost	97,741	3,820	10,120
(Gain) loss on derivative instruments	(44,432)	(16,926)	38,950
Net cash received (paid) in settlement of derivative instruments	(41,631)	8,056	(1,682)
(Earnings) loss on equity method investments	(1,137)	100,486	2,477
Distribution of earnings from equity method investments	1,296	0	0
Amortization of debt issuance costs	4,631	4,774	5,083
Stock-based compensation and other	31,443	33,419	25,982
Changes in assets and liabilities:
Accounts receivable, net	(146,921)	(25,036)	(71,060)
Income taxes	(59,616)	(46,368)	(5,975)
Inventories	(3,927)	1,334	3,044
Other current assets	934	(104)	(21)
Accounts payable and accrued liabilities	30,468	(2,552)	10,858
Interest payable	(7,477)	(75)	(2,573)
Other assets and liabilities	23,079	(5,141)	2,465
Net cash provided by operating activities	1,104,903	898,160	397,441
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(894,470)	(764,558)	(375,153)
Proceeds from sale of assets	678,350	115,444	50,419
Investment in equity method investments	(77,263)	(57,039)	(28,484)
Net cash used in investing activities	(293,383)	(706,153)	(353,218)
CASH FLOWS FROM FINANCING ACTIVITIES
Borrowings from debt	158,000	0	90,000
Repayments of debt	(455,000)	0	(587,000)
Treasury stock repurchases	(872,761)	(123,741)	0
Sale of common stock, net	0	0	995,279
Dividends paid	(111,369)	(78,838)	(36,187)
Tax withholding on vesting of stock awards	(8,150)	(7,973)	(5,064)
Capitalized debt issuance costs	0	0	(3,223)
Other	0	50	0
Net cash (used in) provided by financing activities	(1,289,280)	(210,502)	453,805
Net (decrease) increase in cash and cash equivalents	(477,760)	(18,495)	498,028
Cash and cash equivalents, beginning of period	480,047	498,542	514
Cash and cash equivalents, end of period	$ 2,287	$ 480,047	$ 498,542