Property, Plant and Equipment - Summary of property, plant and equipment (Details) - USD ($) $ in Thousands	Jun. 30, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	$ 24,881	$ 24,284
Less accumulated depreciation and amortization	(15,229)	(14,909)
Total property, plant and equipment	9,652	9,375
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	10,272	7,916
Less accumulated depreciation and amortization	(2,876)	(2,811)
Machinery, equipment and tooling
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	14,228	13,530
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	$ 360	$ 2,817