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 Comprehensive Income [Abstract]
Net loss	$ (21,317)	$ (22,748)	$ (87,074)	$ (64,683)
Change in unrealized gain on available-for-sale debt securities	(192)	13	100	257
Comprehensive loss	$ (21,509)	$ (22,735)	$ (86,974)	$ (64,426)