Condensed Consolidated Statements of Comprehensive Income (Loss) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (444,440)	$ (440,667)	$ 681,313
Other comprehensive income (loss):
Net unrealized gain (loss) on available-for-sale investments	(927)	5,693	(2,975)
Net foreign currency translation gain (loss)	(363)	(382)	(1,230)
Other comprehensive income (loss)	(1,290)	5,311	(4,205)
Comprehensive income (loss)	$ (445,730)	$ (435,356)	$ 677,108