Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Statement of Comprehensive Income [Abstract]
Net loss	$ (25,123)	$ (13,068)	$ (80,277)	$ (29,351)
Other comprehensive (loss) income:
Foreign currency translation adjustment	13	(4)	34	(10)
Comprehensive loss	$ (25,110)	$ (13,072)	$ (80,243)	$ (29,361)