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	$ (9,545)	$ (6,885)	$ (27,939)	$ (18,439)
Other comprehensive (loss) income, net of tax
Foreign currency translation adjustment	6	(2)	(2)	(2)
Change in unrealized (loss) gain on available-for-sale debt securities	(75)	(12)	45	(12)
Comprehensive loss	$ (9,614)	$ (6,899)	$ (27,896)	$ (18,453)