Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Statement [Abstract]
Contract revenues	$ 466,498	$ 385,818	$ 354,544
Costs of contract revenues	426,316	341,224	322,540
Gross profit	40,182	44,594	32,004
Selling, general and administrative expenses	47,715	34,691	32,110
Operating (loss) income	(7,533)	9,903	(106)
Other (expense) income:
(Loss) gain from sale of assets, net	(466)	359	(153)
Other income	536	467	165
Interest income	32	17	13
Interest expense	(3,148)	(694)	(525)
Other (expense) income, net	(3,046)	149	(500)
(Loss) income before income taxes	(10,579)	10,052	(606)
Income tax (benefit) expense	(2,519)	3,175	(937)
Net (loss) income attributable to Orion common stockholders	$ (8,060)	$ 6,877	$ 331
Basic income (loss) per share (USD per share)	$ (0.29)	$ 0.25	$ 0.01
Diluted income (loss) per share (USD per share)	$ (0.29)	$ 0.25	$ 0.01
Shares used to compute (loss) income per share
Basic (in shares)	27,366,528	27,421,441	27,296,732
Diluted (in shares)	27,366,528	27,787,613	27,613,054