Income Taxes - Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Unrecognized Income Tax Benefit [Roll Forward]
Beginning balance, unrecognized tax benefits	$ 42,773	$ 34,152	$ 31,558
Additions based on tax provisions related to the current year	6,412	4,284	3,755
Additions based on tax provisions related to the prior year	13,532	11,679	3,000
Deduction of cumulative interest and penalties	(12,508)
Deductions based on settlement/expiration of prior year tax positions	(14,460)	(7,342)	(4,161)
Ending balance, unrecognized tax benefits	$ 35,749	$ 42,773	$ 34,152