Accrued Expenses and Other Current Liabilities (Details) - Accrued expenses and other current liabilities (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Accrued Expenses And Other Current Liabilities [Abstract]
Accrued salaries and benefits	$ 1,229	$ 1,115
Accrued severance and other charges (1)	462	602
Accrued warranty (2)	343	373	458	453
Warrant liability (3)	2,003	1,474	485	939
Accrued indemnification settlement (4)	650	650
Liability for consigned precious metals	510	565
Other	1,352	1,410
Accrued expenses and other current liabilities	$ 6,549	$ 6,189