Statements of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income Statement [Abstract]
Revenues	$ 15,155	$ 21,082	$ 37,610	$ 43,388
Costs and expenses
Operating costs	7,398	12,057	19,965	25,163
Selling, general and administrative	5,005	3,755	8,626	7,582
Depreciation and amortization	5,816	5,169	11,641	9,458
(Insurance recoveries) asset impairment, net	0	0	0	(841)
Loss (gain) on disposition of assets	37	(59)	(88)	334
Total costs and expenses	18,256	20,922	40,144	41,696
Operating (loss) income	(3,101)	160	(2,534)	1,692
Interest expense	(1,059)	(717)	(2,036)	(1,029)
(Loss) income before income taxes	(4,160)	(557)	(4,570)	663
Income tax expense (benefit)	31	95	35	(60)
Net (loss) income	$ (4,191)	$ (652)	$ (4,605)	$ 723
Net (loss) income per share:
Basic and diluted (usd per share)	$ (0.12)	$ (0.03)	$ (0.16)	$ 0.03
Weighted average number of common shares outstanding:
Basic and diluted (shares)	33,608	23,851	28,812	24,455