Valuation and Qualifying Accounts (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Allowance for Doubtful Accounts
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at beginning of year	$ 973	$ 1,391	$ 955
Charged to Costs and Expenses	1,005	1,239	1,469
Charged to Other Accounts	(121)	51	(270)
Deductions from Reserves	(1,006)	(1,708)	(763)
Balance at end of year	851	973	1,391
Allowance for Deferred Income Tax Assets
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at beginning of year	27,578	19,304	13,418
Charged to Costs and Expenses		6,700	5,706
Charged to Other Accounts	(14,009)	1,574	180
Deductions from Reserves	(3,592)
Balance at end of year	9,977	27,578	19,304
Reserve for Inventory
Valuation And Qualifying Accounts Disclosure [Line Items]
Balance at beginning of year	7,887	4,790	4,308
Charged to Costs and Expenses	2,712	3,521	876
Charged to Other Accounts	(1,047)	302	(68)
Deductions from Reserves	(3,282)	(726)	(326)
Balance at end of year	$ 6,270	$ 7,887	$ 4,790