Valuation Allowance of Deferred Tax Assets (Detail) - Valuation Allowance of Deferred Tax Assets - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Valuation and Qualifying Accounts Disclosure [Line Items]
Beginning Balance	$ 60,359	$ 54,725	$ 35,246
Additions	144,239	7,611	22,005
Deductions	(992)	(1,977)	(2,526)
Ending Balance	$ 203,606	$ 60,359	$ 54,725