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	$ (5,858)	$ (17,640)	$ (40,795)	$ (60,708)
Other comprehensive (loss) income, net of tax:
Unrealized (losses) gains on available-for-sale securities	(95)	(20)	4	60
Other comprehensive (loss) income	(95)	(20)	4	60
Comprehensive loss	$ (5,953)	$ (17,660)	$ (40,791)	$ (60,648)