Equipment and Leasehold Improvements (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 20,853	$ 20,376
Less: Accumulated depreciation and amortization	(19,229)	(18,981)
Property, Plant and Equipment, Net, Total	1,624	1,395
Machinery and Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	14,936	14,587
Office Equipment [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	811	790
Office Furniture [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	110	110
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	4,839	4,815
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Gross	$ 157	$ 75