Condensed Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Statement of Comprehensive Income [Abstract]
Net loss	$ (105,697)	$ (82,939)
Other comprehensive loss, before tax:
Unrealized gain (loss) on available-for-sale investments	(1,642)	2,176
Foreign currency translation gain (loss)	25	0
Comprehensive loss, before tax	(107,314)	(80,763)
Income tax benefit (expense) related to items of other comprehensive loss	0	(520)
Comprehensive loss, net of tax	$ (107,314)	$ (81,283)