Component of Accrued Warranty Expenses (Detail) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Warranty Liability [Line Items]
Accrued warranty beginning balance	$ 690	$ 564
Warranty costs incurred	(571)	(553)
Provision for warranty expense	550	524
Accrued warranty ending balance	$ 669	$ 535