CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement of Comprehensive Income [Abstract]
Net loss	$ (11,960)	$ (21,628)	$ (34,937)	$ (43,068)
Other comprehensive (loss) income, net of tax:
Unrealized (losses) gains on available-for-sale securities	(14)	59	99	80
Other comprehensive (loss) income	(14)	59	99	80
Comprehensive loss	$ (11,974)	$ (21,569)	$ (34,838)	$ (42,988)