Accrued Expenses and Other Current Liabilities (Detail) - Accrued expenses and other current liabilities (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Accrued salaries and benefits	$ 1,347	$ 1,486
Accrued severance and other charges	490
Sales tax payable	216	566
Accrued warranty	665	645	466
Deferred revenue		650
Liability for consigned precious metals	694	652
Warrant liability	10	100
Other	1,092	916
Accrued expenses and other current liabilities	$ 4,514	$ 5,015