Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (14,540)	$ (20,952)	$ (38,730)	$ (62,957)
Other comprehensive loss:
Unrealized (loss) gain on marketable securities, net of tax of $0	(68)	(7)	(40)	324
Foreign currency translation adjustments, net of tax of $0	875	(1,213)	872	(1,442)
Other comprehensive gain (loss)	807	(1,220)	832	(1,118)
Comprehensive loss	$ (13,733)	$ (22,172)	$ (37,898)	$ (64,075)