Product Warranty Accrual Included in Other Accrued Liabilities (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Other Accrued Liabilities [Line Items]
Balance as of January 1	$ 20,132	$ 20,520
Provision for warranties issued in current year	3,580	2,792
(Recovery of) Provision for pre-existing warranties	0	(225)
Payments	(2,671)	(3,351)
Balance as of June 30	$ 21,041	$ 19,736