Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Income Statement [Abstract]
Contract revenues	$ 164,017	$ 137,061	$ 433,941	$ 304,607
Costs of contract revenues	139,849	128,783	378,116	281,848
Gross profit	24,168	8,278	55,825	22,759
Selling, general and administrative expenses	15,291	14,496	47,728	31,982
(Gain) loss on sale of assets, net	(654)	2,107	(1,260)	2,007
Operating income (loss) from operations	9,531	(8,325)	9,357	(11,230)
Other (expense) income
Other income	10	190	32	190
Interest income	0	13	1	30
Interest expense	(1,578)	(943)	(4,695)	(1,433)
Other expense, net	(1,568)	(740)	(4,662)	(1,213)
Income (loss) before income taxes	7,963	(9,065)	4,695	(12,443)
Income tax expense (benefit)	3,224	(1,669)	1,972	(2,945)
Net income (loss)	$ 4,739	$ (7,396)	$ 2,723	$ (9,498)
Basic income (loss) per share (in dollars per share)	$ 0.17	$ (0.27)	$ 0.10	$ (0.35)
Diluted income (loss) per share (in dollars per share)	$ 0.17	$ (0.27)	$ 0.10	$ (0.35)
Shares used to compute income (loss) per share
Basic (in shares)	27,462,794	27,243,128	27,485,730	27,397,342
Diluted (in shares)	27,463,987	27,243,128	27,485,730	27,397,342