Condensed Statements of Comprehensive Loss (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Statement Of Income And Comprehensive Income [Abstract]
Net Loss	$ (26,615)	$ (21,018)	$ (71,514)	$ (68,480)
Other comprehensive loss:
Unrealized gains (losses) on investments	(4)		(12)
Comprehensive loss	$ (26,619)	$ (21,018)	$ (71,526)	$ (68,480)