Income Taxes - Income (Loss) Before Provision for Income Taxes (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Domestic	$ (445,370)	$ (441,494)	$ 680,423
Foreign	1,423	1,440	2,302
Income (loss) before provision for income taxes	$ (443,947)	$ (440,054)	$ 682,725