Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Net loss	$ (29,126)	$ (59,995)	$ (75,595)
Other comprehensive (loss) income:
Unrealized (loss) gain on available-for-sale securities, net of tax of $0, $0, and $0	(2)	(65)	72
Reclassifications of gain on available-for-sale securities, included in “Other income (expenses)," net of tax of $0, $0, and $0	0	3	2
Comprehensive loss	$ (29,128)	$ (60,057)	$ (75,521)