Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income Statement [Abstract]
Contract revenues	$ 140,301	$ 86,091	$ 269,924	$ 167,546
Costs of contract revenues	123,355	80,066	238,267	153,065
Gross profit	16,946	6,025	31,657	14,481
Selling, general and administrative expenses	16,899	8,794	32,437	17,486
Gain on sale of assets, net	(234)	(57)	(606)	(100)
Operating income (loss) from operations	281	(2,712)	(174)	(2,905)
Other (expense) income
Other income	9	0	22	0
Interest income	0	4	1	17
Interest expense	(1,600)	(252)	(3,117)	(490)
Other expense, net	(1,591)	(248)	(3,094)	(473)
Loss before income taxes	(1,310)	(2,960)	(3,268)	(3,378)
Income tax benefit	(502)	(1,115)	(1,252)	(1,276)
Net loss attributable to Orion	$ (808)	$ (1,845)	$ (2,016)	$ (2,102)
Basic (loss) income per share (in dollars per share)	$ (0.03)	$ (0.07)	$ (0.07)	$ (0.08)
Diluted (loss) income per share (in dollars per share)	$ (0.03)	$ (0.07)	$ (0.07)	$ (0.08)
Shares used to compute loss per share
Basic (in shares)	27,464,683	27,352,523	27,383,748	27,478,514
Diluted (in shares)	27,464,683	27,352,523	27,383,748	27,478,514