Property, Plant and Equipment - Summary of property, plant and equipment (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	$ 21,130	$ 19,647
Less accumulated depreciation and amortization	(14,270)	(13,701)
Total property, plant and equipment	6,860	5,946
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	7,851	7,256
Less accumulated depreciation and amortization	(2,682)	(2,552)
Machinery, equipment and tooling
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	$ 13,258	$ 12,370