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	$ (418,259)	$ (132,694)	$ (184,748)
Other comprehensive income (loss):
Net unrealized gains on marketable securities available-for-sale	9	5	12
Foreign currency translation adjustment	19,523	(1,322)	(2,586)
Foreign currency translation adjustment	19,532	(1,317)	(2,574)
Comprehensive loss	$ (398,727)	$ (134,011)	$ (187,322)