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	$ (10,855)	$ (10,725)	$ (23,359)	$ (32,298)
Other comprehensive income (loss):
Net unrealized gain (loss) on marketable debt securities		14		14
Total comprehensive loss	$ (10,855)	$ (10,711)	$ (23,359)	$ (32,284)