Accrued Warranty Costs - Changes in Product Warranty Obligation (Accrued Warranty Costs) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Disclosure Accrued Product Warranty Costs [Abstract]
Balance at beginning of period	$ 7,578	$ 6,486	$ 7,297	$ 6,172
Amounts charged to costs and expenses	1,468	2,021	3,695	4,011
Costs incurred	(1,345)	(1,563)	(3,291)	(3,239)
Balance at end of period	$ 7,701	$ 6,944	$ 7,701	$ 6,944