Condensed Consolidated Statements of Operations (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Contract revenues	$ 140,162	$ 164,017	$ 416,339	$ 433,941
Costs of contract revenues	129,405	139,849	377,200	378,116
Gross profit	10,757	24,168	39,139	55,825
Selling, general and administrative expenses	16,524	15,291	49,031	47,728
Gain on sale of assets, net	(413)	(654)	(590)	(1,260)
Operating (loss) income from operations	(5,354)	9,531	(9,302)	9,357
Other (expense) income
Other income	9	10	30	32
Interest income	11	0	11	1
Interest expense	(1,369)	(1,578)	(4,186)	(4,695)
Other expense, net	(1,349)	(1,568)	(4,145)	(4,662)
(Loss) income before income taxes	(6,703)	7,963	(13,447)	4,695
Income tax (benefit) expense	(1,666)	3,224	(4,309)	1,972
Net (loss) income	$ (5,037)	$ 4,739	$ (9,138)	$ 2,723
Basic (loss) income per share (in dollars per share)	$ (0.18)	$ 0.17	$ (0.33)	$ 0.10
Diluted (loss) income per share (in dollars per share)	$ (0.18)	$ 0.17	$ (0.33)	$ 0.10
Shares used to compute (loss) income per share
Basic (in shares)	27,950,829	27,462,794	27,980,074	27,485,730
Diluted (in shares)	27,950,829	27,463,987	27,980,074	27,485,730