Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net loss	$ (110,078)	$ (40,696)	$ (77,400)
Other comprehensive income (loss):
Change in unrealized (loss) gain on available-for-sale debt securities	(62)	185	59
Comprehensive loss	$ (110,140)	$ (40,511)	$ (77,341)