Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Statement of Comprehensive Income [Abstract]
Net loss	$ (219,884)	$ (40,525)	$ (411,723)	$ (161,966)
Other comprehensive loss, before tax:
Unrealized gain on available-for-sale investments	(405)	(2,697)	1,159	1,431
Foreign currency adjustment	0	0	25	0
Comprehensive loss, before tax	(220,289)	(43,222)	(410,539)	(160,535)
Income tax expense related to items of other comprehensive loss	0	643	0	(341)
Comprehensive loss, net of tax	$ (220,289)	$ (42,579)	$ (410,539)	$ (160,876)