Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities
Net income (loss)	$ 35,929	$ (565,861)
Adjustments to reconcile net income (loss) to cash flows from operating activities
Depletion, depreciation, and amortization	102,347	143,907
Write-down of oil and natural gas properties	0	735,400
Deferred income taxes	51,147	(318,055)
Stock-based compensation	8,941	4,122
Commodity derivatives expense (income)	(34,975)	121,035
Receipt (payment) on settlements of commodity derivatives	(38,707)	124,253
Gain on debt extinguishment	0	(107,269)
Debt issuance costs and discounts	3,344	14,072
Other, net	(1,006)	(1,743)
Changes in assets and liabilities, net of effects from acquisitions
Accrued production receivable	21,114	(20,060)
Trade and other receivables	(17,916)	17,568
Other current and long-term assets	(10,225)	(7,974)
Accounts payable and accrued liabilities	(26,611)	(71,830)
Oil and natural gas production payable	(12,652)	(3,624)
Other liabilities	(3,522)	(997)
Net cash provided by operating activities	77,208	62,944
Cash flows from investing activities
Oil and natural gas capital expenditures	(129,884)	(126,302)
Acquisitions of oil and natural gas properties	(89,208)	(904)
Other	(2,058)	(314)
Net cash used in investing activities	(221,150)	(127,520)
Cash flows from financing activities
Bank repayments	(796,000)	(994,000)
Bank borrowings	985,000	1,139,000
Interest payments on senior secured notes treated as a reduction of debt	(25,139)	0
Repurchases of senior subordinated notes	0	(55,521)
Pipeline financing and capital lease debt repayments	(13,728)	(14,336)
Other	(4,289)	(10,834)
Net cash provided by financing activities	145,844	64,309
Net increase (decrease) in cash and cash equivalents	1,902	(267)
Cash and cash equivalents at beginning of period	1,606	2,812
Cash and cash equivalents at end of period	$ 3,508	$ 2,545