CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
CONSOLIDATED STATEMENTS OF COMPREHENSIVE LOSS
Net loss	$ (199,426)	$ (278,017)	$ (236,455)
Other comprehensive income (loss):
Net unrealized gain (loss) on available-for-sale investments, net of tax	(47)	(98)	311
Comprehensive loss	$ (199,473)	$ (278,115)	$ (236,144)