Condensed Consolidated Statements of Operations - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Income Statement [Abstract]
Contract revenues	$ 137,061	$ 106,976	$ 304,607	$ 278,485
Costs of contract revenues	128,783	94,070	281,848	252,060
Gross profit	8,278	12,906	22,759	26,425
Selling, general and administrative expenses	14,496	7,859	31,982	23,953
(Loss) income from operations	(6,218)	5,047	(9,223)	2,472
Other (expense) income
(Loss) gain from sale of assets, net	(2,107)	(12)	(2,007)	165
Other income	190	1	190	467
Interest income	13	0	30	12
Interest expense	(943)	(198)	(1,433)	(523)
Other (expense) income, net	(2,847)	(209)	(3,220)	121
(Loss) income before income taxes	(9,065)	4,838	(12,443)	2,593
Income tax (benefit) expense	(1,669)	1,876	(2,945)	1,006
Net (loss) income attributable to Orion common stockholders	$ (7,396)	$ 2,962	$ (9,498)	$ 1,587
Basic (loss) income per share (in dollars per share)	$ (0.27)	$ 0.11	$ (0.35)	$ 0.06
Diluted (loss) income per share (in dollars per share)	$ (0.27)	$ 0.11	$ (0.35)	$ 0.06
Shares used to compute (loss) income per share
Basic (shares)	27,243,128	27,468,240	27,397,342	27,430,162
Diluted (shares)	27,243,128	27,802,734	27,397,342	27,809,208