Condensed 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 Income And Comprehensive Income [Abstract]
Net loss	$ (8,450)	$ (4,231)	$ (37,710)	$ (13,870)
Other comprehensive income (loss):
Foreign currency translation adjustment, net of taxes	81	197	(2,570)	323
Total comprehensive loss	$ (8,369)	$ (4,034)	$ (40,280)	$ (13,547)