Valuation and Qualifying Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Allowance for Doubtful Accounts
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	$ 1,193	$ 851	$ 973
Charged to Costs and Expenses	1,298	969	1,005
Charged to Other Accounts	33	(8)	(121)
Deductions from Reserves	(1,363)	(619)	(1,006)
Balance at End of Period	1,161	1,193	851
Allowance for Deferred Income Tax Assets
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	17,316	9,977	27,578
Charged to Costs and Expenses		7,830
Charged to Other Accounts	139	(491)	(14,009)
Deductions from Reserves	(258)		(3,592)
Balance at End of Period	17,197	17,316	9,977
Reserve for Inventory
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Period	6,073	6,270	7,887
Charged to Costs and Expenses	1,768	1,679	2,712
Charged to Other Accounts	214	(56)	(1,047)
Deductions from Reserves	(914)	(1,820)	(3,282)
Balance at End of Period	$ 7,141	$ 6,073	$ 6,270