CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net loss	$ (11,627)	$ (45,192)	$ (67,462)
Other comprehensive income (loss):
Foreign currency translation adjustments	1,398	(364)	(82)
Comprehensive loss	$ (10,229)	$ (45,556)	$ (67,544)