Consolidated Statements of Comprehensive Income (Loss) Statement - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (10,273)	$ 23,293	$ 10,246
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Foreign currency translation adjustments	190	(766)	44
Total comprehensive income (loss)	(10,083)	22,527	10,290
Less: comprehensive income attributable to noncontrolling interest	(912)	(234)	(416)
Comprehensive income (loss) attributable to controlling interest	$ (10,995)	$ 22,293	$ 9,874