Property, Plant and Equipment - Summary of property, plant and equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	$ 32,050	$ 30,062
Less accumulated depreciation and amortization	(19,333)	(18,187)
Property, plant and equipment, net	12,717	11,875
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	7	7
Buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	11,017	10,452
Machinery, equipment and tooling
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	20,695	18,345
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	$ 331	$ 1,258