Accrued Liabilities (Detail) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Schedule of Accrued Liabilities [Line Items]
Accrued compensation and related costs	$ 2,692	$ 2,027
Accrued inventory costs	2,352	1,417
Accrued contract and other accrued expenses	2,575	2,381
Total accrued liabilities	$ 7,619	$ 5,825