Property, Plant and Equipment - Summary of property, plant and equipment (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	$ 25,533	$ 25,355
Less accumulated depreciation and amortization	(15,804)	(15,600)
Total property, plant and equipment	9,729	9,755
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	21	21
Buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	10,359	10,343
Machinery, equipment and tooling
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	15,076	14,934
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	$ 77	$ 57