Condensed 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	$ (30,025)	$ (20,650)
Other comprehensive loss:
Unrealized loss on available-for-sale securities	(9)	(35)
Comprehensive loss	$ (30,034)	$ (20,685)