Income Taxes - Reconciliation of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Balance at January 1	$ 25,993	$ 11,832	$ 9,300
Additions based on tax positions related to the current year	3,119	3,224	1,354
Additions for tax positions of prior years	474	593	1,624
Reductions for tax positions of prior years	(186)	(174)	(148)
Settlement of tax audits	0	(7)	0
Unrecognized Tax Benefits, Increase Resulting from Acquisition	0	11,006	0
Reductions due to lapsed statute of limitations	(1,098)	(481)	(298)
Balance at December 31	$ 28,302	$ 25,993	$ 11,832