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	$ (24,103)	$ (10,265)	$ (57,118)	$ (41,712)
Other comprehensive income (loss)—Foreign currency translation	(242)	1,719	(2,687)	2,518
Total comprehensive loss	$ (24,345)	$ (8,546)	$ (59,805)	$ (39,194)