Property, Plant and Equipment - Summary of property, plant and equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	$ 26,056	$ 25,355
Less accumulated depreciation and amortization	(16,006)	(15,600)
Total property, plant and equipment	10,050	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	10,413	10,343
Machinery, equipment and tooling
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	15,559	14,934
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	$ 63	$ 57