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	$ (27,221)	$ (12,818)	$ (73,955)	$ (33,068)
Other comprehensive income (loss):
Unrealized gain (loss) on investments, net	(80)	69	137	54
Total comprehensive loss	$ (27,301)	$ (12,749)	$ (73,818)	$ (33,014)