CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS (UNAUDITED) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Statement Of Income And Comprehensive Income [Abstract]
Net loss	$ (35,340)	$ (26,270)	$ (70,671)	$ (50,122)
Other comprehensive gain (loss):
Change in unrealized gain (loss) on available for sale securities, net	30	180	(172)	263
Total other comprehensive gain (loss)	30	180	(172)	263
Comprehensive loss	$ (35,310)	$ (26,090)	$ (70,843)	$ (49,859)