Income Taxes - Schedule of Gross Unrecognized Tax Benefits (Excluding Interest and Penalties) (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Income Tax Disclosure [Abstract]
Beginning Balance	$ 16,904	$ 21,351
Additions for current year tax positions	568	309
Increases for prior year tax positions	84	1,711
Settlements of prior year tax positions	(29)	(1,183)
Expiration of statutes	(12,898)	(5,284)
Ending Balance	$ 4,629	$ 16,904