Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Statement of Comprehensive Income [Abstract]
Net loss	$ (122,967)	$ (138,651)
Other comprehensive income (loss):
Net unrealized gain (loss) on available-for-sale investments	(766)	(5,121)
Net foreign currency translation gain (loss)	(60)	(751)
Other comprehensive income (loss)	(826)	(5,872)
Comprehensive loss	$ (123,793)	$ (144,523)