Accrued Expenses and Other Current Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Accrued Expenses and Other Current Liabilities
Accrued salaries and benefits	$ 1,332	$ 1,115
Accrued severance and other charges	1,092	335
Accrued warranty	228	373	$ 453
Warrant liability	3,072	1,474
Accrued indemnification settlement		650
Liability for consigned precious metals	543	565
Other	1,587	1,677
Accrued expenses and other current liabilities	$ 7,854	$ 6,189