CONDENSED CONSOLIDATED STATEMENT OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
CASH FLOWS FROM OPERATING ACTIVITIES
Net income (loss)	$ 105,720	$ (51,194)
Adjustments to reconcile net income (loss) to cash provided by operating activities:
Depreciation, depletion and amortization	135,100	161,887
Deferred income tax expense (benefit)	53,289	(28,973)
(Gain) loss on sale of assets	223	(1,354)
Exploratory dry hole cost	2,842	0
Gain on derivative instruments	(33,384)	(18,994)
Net cash paid in settlement of derivative instruments	(1,524)	0
(Earnings) loss on equity method investments	1,283	(2,009)
Amortization of debt issuance costs	1,189	1,191
Stock-based compensation and other	8,283	10,606
Changes in assets and liabilities:
Accounts receivable, net	(1,738)	19,358
Income taxes	10,534	233
Inventories	1,209	1,101
Other current assets	1,170	1,300
Accounts payable and accrued liabilities	151	(9,610)
Interest payable	(15,388)	(16,660)
Other assets and liabilities	419	230
Net cash provided by operating activities	269,378	67,112
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures	(208,384)	(92,237)
Proceeds from sale of assets	374	49,828
Investment in equity method investments	(7,742)	(11,652)
Net cash used in investing activities	(215,752)	(54,061)
CASH FLOWS FROM FINANCING ACTIVITIES
Borrowings from debt	0	90,000
Repayments of debt	0	(503,000)
Sale of common stock, net	0	995,278
Dividends paid	(9,306)	(8,282)
Tax withholdings on stock award vestings	(5,414)	(5,022)
Capitalized debt issuance costs	0	(3,223)
Other	37	0
Net cash provided by (used in) financing activities	(14,683)	565,751
Net increase in cash and cash equivalents	38,943	578,802
Cash and cash equivalents, beginning of period	498,542	514
Cash and cash equivalents, end of period	537,485	579,316
Supplemental non-cash investing transactions:
Change in accrued capital costs	$ 6,695	$ (549)