Condensed Consolidated Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (18,218)	$ (18,728)
Other comprehensive income (loss):
Foreign currency translation adjustment	4
Unrealized gain (loss) on marketable securities	10	(185)
Total comprehensive loss	$ (18,204)	$ (18,913)