Accrued Warranty Expense (Detail) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013
Warranty Liability [Line Items]
Accrued warranty beginning balance	$ 737	$ 690
Warranty costs incurred	(742)	(854)
Provision for warranty expense	689	926
Accrued warranty ending balance	$ 684	$ 762