Condensed Consolidated Statements of Cash Flows - Unaudited - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Operating activities
Net loss	$ (213,414)	$ (207,213)
Adjustments to reconcile net loss to net cash provided by operating activities
Unrealized loss on derivatives	33,464	32,090
Depletion, depreciation and amortization	60,170	98,239
Accretion of asset retirement obligations	552	244
Full-cost ceiling impairment	158,633	296,153
Stock-based compensation expense	5,553	5,131
Deferred income tax benefit		(115,740)
Amortization of debt issuance cost	592	0
Net (gain) loss on asset sales and inventory impairment	(2,067)	97
Changes in operating assets and liabilities
Accounts receivable	(2,751)	(12,161)
Lease and well equipment inventory	(514)	(269)
Prepaid expenses	186	(1,143)
Other assets	520	446
Accounts payable, accrued liabilities and other current liabilities	2,451	13,316
Royalties payable	153	4,253
Advances from joint interest owners	5,083	447
Income taxes payable	(2,848)	(444)
Other long-term liabilities	3,837	(56)
Net cash provided by operating activities	49,600	113,390
Investing activities
Oil and natural gas properties capital expenditures	(162,381)	(237,027)
Expenditures for other property and equipment	(47,548)	(32,885)
Business combination, net of cash acquired	0	(23,671)
Restricted cash	43,437	0
Restricted cash in less-than-wholly-owned subsidiaries	460	(413)
Net cash used in investing activities	(166,032)	(293,996)
Financing activities
Repayments of borrowings	0	(476,982)
Borrowings under Credit Agreement	0	125,000
Proceeds from issuance of senior unsecured notes	0	400,000
Cost to issue senior unsecured notes	0	(8,789)
Proceeds from issuance of common stock	142,350	188,720
Cost to issue equity	(768)	(1,172)
Proceeds from stock options exercised	0	10
Capital contribution from non-controlling interest owners in less-than-wholly-owned subsidiaries	0	600
Taxes paid related to net share settlement of stock-based compensation	(1,009)	(1,565)
Net cash provided by financing activities	140,573	225,822
Increase in cash	24,141	45,216
Cash at beginning of period	16,732	8,407
Cash at end of period	$ 40,873	$ 53,623