Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
Contract revenues	$ 578,553	$ 578,236	$ 466,498
Costs of contract revenues	511,663	510,754	426,316
Gross profit	66,890	67,482	40,182
Selling, general and administrative expenses	66,026	64,987	47,715
Gain (Loss) on Disposition of Assets	(674)	(1,579)	466
Operating income (loss)	1,538	4,074	(7,999)
Other (expense) income:
(Gain) loss from sale of assets, net	674	1,579	(466)
Other income	41	59	536
Interest income	11	3	32
Interest expense	(5,731)	(6,175)	(3,148)
Other (expense) income, net	(5,679)	(6,113)	(2,580)
Loss before income taxes	(4,141)	(2,039)	(10,579)
Income tax (benefit) expense	(4,541)	1,581	(2,519)
Net income (loss)	$ 400	$ (3,620)	$ (8,060)
Basic income (loss) per share (USD per share)	$ 0.01	$ (0.13)	$ (0.29)
Diluted income (loss) per share (USD per share)	$ 0.01	$ (0.13)	$ (0.29)
Shares used to compute income (loss) per share
Basic (in shares)	28,029,936	27,536,967	27,366,528
Diluted (in shares)	28,354,280	27,536,967	27,366,528