Income Taxes - Reconciliation of Income Tax Benefit (Provision) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Expected tax benefit (expense) at federal statutory rate	$ 97,423	$ 7,402
State income tax benefit (expense), net of federal benefit	6,189	946
Non-deductible expenses	(45)	(3,659)
Changes in valuation allowances	(110,445)	(4,332)
State rate change, net of federal benefit	6,100	0
Non-cash compensation	(137)	(367)
Other	800	60
Total income tax benefit (expense)	$ (115)	$ 50