Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Revenues:
Oil and gas sales	$ 108,287	$ 66,667	$ 115,969
Expenses:
Lease operating expenses	33,162	28,508	40,130
Production taxes	3,302	354	2,470
Depreciation, depletion and amortization	32,053	28,720	63,497
Ceiling test write-down	0	40,304	266,562
General and administrative	15,860	26,040	20,777
Accretion of asset retirement obligation	2,252	2,515	3,259
Interest expense	28,836	30,019	33,766
Total expenses	115,465	156,460	430,461
Other income (expense):
Gain on sale of assets	0	0	21,937
Other income (expense)	(408)	(560)	391
Other income (expense), net	(408)	(560)	22,328
Loss from operations	(7,586)	(90,353)	(292,164)
Income tax expense (benefit)	(949)	543	2,626
Net loss	(6,637)	(90,896)	(294,790)
Preferred stock dividend	5,139	5,349	5,139
Net loss available to common stockholders	$ (11,776)	$ (96,245)	$ (299,929)
Basic
Net loss per share (in usd per share)	$ (0.55)	$ (5.24)	$ (18.45)
Diluted
Net loss per share (in usd per share)	$ (0.55)	$ (5.24)	$ (18.45)
Weighted average number of common shares:
Basic (shares)	21,330	18,354	16,256
Diluted (shares)	21,330	18,354	16,256