Schedule II - Valuation and Qualifying Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowance for Doubtful Accounts
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	$ 4,860	$ 5,369	$ 5,540
Charged to costs and expenses	1,172	2,015	375
Deductions from reserves, net	688	2,524	546
Balance at end of year	5,344	4,860	5,369
Income Tax Valuation Allowance
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	5,936	5,039	4,559
Charged to costs and expenses	2,854	1,138	859
Deductions from reserves, net	1,602	241	379
Balance at end of year	$ 7,188	$ 5,936	$ 5,039