Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Consolidated Statements of Comprehensive Loss [Abstract]
Net loss	$ (139,700)	$ (77,270)	$ (74,518)
Other comprehensive loss
Net unrealized (loss) gain on investments	(62)	147	(127)
Total comprehensive loss	$ (139,762)	$ (77,123)	$ (74,645)