Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (113,698)	$ (76,073)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities
Depreciation, depletion and amortization	36,062	103,073
Exploration expense	18,722	6,073
Pension benefit costs	0	101
Stock-based compensation	3,701	2,157
Impairment of proved oil and gas properties	17,665	0
Accretion of asset retirement obligations	175	785
(Gain) loss on derivative instruments	19,046	(7,848)
Net cash receipts (payments) on settled derivatives	31,258	14,422
(Gain) loss on sale of assets	(1,046)	(5,473)
Gain on early extinguishment of debt	(14,489)	0
Deferred income taxes	540	(34,107)
Interest not paid in cash	0	1,232
Amortization of deferred financing costs	972	1,018
Amortization of debt discount	691	1,193
Changes in operating assets and liabilities, net of acquisitions:
Accounts receivable	(1,238)	13,007
Other assets	(2,586)	225
Accounts payable and accrued liabilities	(13,026)	29,724
Net cash provided by (used in) operating activities	(17,251)	49,509
CASH FLOWS FROM INVESTING ACTIVITIES
Capital expenditures for oil and gas properties	(42,913)	(327,856)
Capital expenditures for other property and equipment	(416)	(1,284)
Proceeds from sale of assets	14,094	37,287
Net cash used in investing activities	(29,235)	(291,853)
CASH FLOWS FROM FINANCING ACTIVITIES
Debt issuance costs	261	(1,577)
Repayments of long-term debt	(23,786)	(207)
Proceeds from issuance of common stock	0	440,000
Equity issuance costs	(277)	(5,767)
Employee tax withholding for settlement of equity compensation awards	(61)	0
Net cash provided by (used in) financing activities	(23,863)	432,449
Net increase (decrease) in cash and cash equivalents	(70,349)	190,105
Cash and cash equivalents at beginning of period	184,405	67,517
Cash and cash equivalents at end of period	114,056	257,622
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION:
Cash paid for interest	25,175	13,080
Cash paid for income taxes	0	37
SUPPLEMENTAL DISCLOSURE OF NON-CASH ACTIVITIES:
Asset retirement obligations incurred, including changes in estimate	63	303
Additions of other property through debt financing	0	888
Additions to oil and natural gas properties - changes in accounts payable, accrued liabilities, and accrued capital expenditures	123	(88,418)
Interest paid-in-kind	$ 0	$ 14,786