CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Natural gas sales	$ 208,741	$ 122,623	$ 109,753
Oil sales	46,590	53,083	142,669
Total oil and gas sales	255,331	175,706	252,422
Operating expenses:
Production taxes	5,373	4,933	10,286
Gathering and transportation	17,538	15,824	14,298
Lease operating	37,859	47,696	64,502
Exploration		84,144	70,694
Depreciation, depletion and amortization	123,557	141,487	321,323
General and administrative, net	26,137	23,963	23,541
Impairment of oil and gas properties	43,990	27,134	801,347
Loss on sale of oil and gas properties	1,060	14,315	112,085
Total operating expenses	255,514	359,496	1,418,076
Operating loss	(183)	(183,790)	(1,165,654)
Other income (expenses):
Gain (loss) from derivative financial instruments	16,753	(5,356)	2,676
Net gain on extinguishment of debt		189,052	78,741
Interest expense	(146,449)	(128,743)	(118,592)
Other income	530	872	1,275
Total other income (expenses)	(129,166)	55,825	(35,900)
Loss before income taxes	(129,349)	(127,965)	(1,201,554)
Benefit from (provision for) income taxes	17,944	(7,169)	154,445
Net loss	$ (111,405)	$ (135,134)	$ (1,047,109)
Net loss per share – basic and diluted	$ (7.61)	$ (11.52)	$ (113.53)
Basic and diluted weighted average shares outstanding	14,644	11,729	9,223