Condensed Consolidated Statements of Comprehensive Loss - 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	$ (24,060)	$ (12,862)	$ (25,480)	$ (39,961)
Unrealized gain (loss) on available-for-sale securities	(216)	56	(46)	607
Comprehensive loss	$ (24,276)	$ (12,806)	$ (25,526)	$ (39,354)