Income Taxes - Schedule of Reconciliation of Beginning and Ending Amount of Gross Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Disclosure [Abstract]
Gross unrecognized tax benefits, beginning of the year	$ 9,859	$ 9,009	$ 8,564
Additions for tax positions of prior years			5
Additions for tax positions related to the current year	2,954	1,957	1,839
Reductions for tax positions of prior years	(51)	(58)
Reductions due to lapse of applicable statute of limitations	(968)	(1,049)	(1,399)
Subtotal	11,794	9,859	9,009
Interest and penalties	1,919	1,901	1,862
Total gross unrecognized tax benefits, end of the year	$ 13,713	$ 11,760	$ 10,871