CONDENSED CONSOLIDATED STATEMENT OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 262,763	$ 117,231
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation, depletion and amortization	92,258	82,128
Deferred income tax expense	88,002	64,287
Loss on sale of assets	1,500	41,049
Exploratory dry hole cost	13	(60)
Gain on derivative instruments	(8,257)	(5,577)
Net cash received (paid) in settlement of derivative instruments	52,980	(26,131)
(Earnings) loss on equity method investments	(3,684)	994
Distribution of earnings from equity method investments	4,729	0
Amortization of debt issuance costs	1,089	1,195
Stock-based compensation and other	14,474	5,184
Changes in assets and liabilities:
Accounts receivable, net	141,671	50,216
Income taxes	6,786	(24,646)
Inventories	(7,201)	(4,309)
Other current assets	1,119	1,023
Accounts payable and accrued liabilities	(27,934)	(14,169)
Interest payable	(12,887)	(15,318)
Other assets and liabilities	(22,134)	(337)
Net cash provided by operating activities	585,287	272,760
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(195,650)	(156,257)
Proceeds from sale of assets	2,346	646,545
Investment in equity method investments	(1,828)	(35,418)
Net cash provided by (used in) investing activities	(195,132)	454,870
CASH FLOWS FROM FINANCING ACTIVITIES
Borrowings from debt	95,000	0
Repayments of debt	(102,000)	0
Treasury stock repurchases	(31,378)	(207,134)
Dividends paid	(29,605)	(27,647)
Tax withholdings on vesting of stock awards	(9,570)	(7,968)
Net cash used in financing activities	(77,553)	(242,749)
Net increase in cash and cash equivalents	312,602	484,881
Cash and cash equivalents, beginning of period	2,287	480,047
Cash and cash equivalents, end of period	$ 314,889	$ 964,928