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	$ (28,232)	$ (29,627)	$ (98,903)	$ (79,749)
Other comprehensive gain (loss):
Change in unrealized gain (loss) on available for sale securities, net	(11)	68	(183)	331
Total other comprehensive gain (loss)	(11)	68	(183)	331
Comprehensive loss	$ (28,243)	$ (29,559)	$ (99,086)	$ (79,418)