CONDENSED CONSOLIDATED STATEMENT OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
CASH FLOWS FROM OPERATING ACTIVITIES
Net income	$ 443,772	$ 159,662
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation, depletion and amortization	188,405	167,038
Deferred income tax expense	152,647	66,976
Loss on sale of assets	1,500	40,505
Exploratory dry hole cost	16	51,085
Gain on derivative instruments	(71,906)	(1,909)
Net cash received (paid) in settlement of derivative instruments	68,377	(20,312)
(Earnings) loss on equity method investments	(7,334)	998
Distribution of earnings from equity method investments	8,750	0
Amortization of debt issuance costs	2,464	2,390
Stock-based compensation and other	21,058	10,364
Changes in assets and liabilities:
Accounts receivable, net	179,027	38,939
Income taxes	(5,577)	12,107
Inventories	(8,305)	(12,377)
Other current assets	(2,263)	(1,096)
Accounts payable and accrued liabilities	(35,867)	7,168
Interest payable	(216)	(215)
Other assets and liabilities	(22,611)	25,337
Net cash provided by operating activities	911,937	546,660
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(421,500)	(387,271)
Proceeds from sale of assets	2,346	646,868
Investment in equity method investments	(5,131)	(62,905)
Distribution of investment from equity method investments	758	0
Net cash (used in) provided by investing activities	(423,527)	196,692
CASH FLOWS FROM FINANCING ACTIVITIES
Borrowings from debt	95,000	0
Repayments of debt	(102,000)	0
Treasury stock repurchases	(156,638)	(419,654)
Dividends paid	(67,697)	(54,718)
Tax withholdings on vesting of stock awards	(10,557)	(8,033)
Capitalized debt issuance costs	(7,411)	0
Net cash used in financing activities	(249,303)	(482,405)
Net increase in cash and cash equivalents	239,107	260,947
Cash and cash equivalents, beginning of period	2,287	480,047
Cash and cash equivalents, end of period	$ 241,394	$ 740,994