Property, Plant and Equipment - Summary of property, plant and equipment (Details) - USD ($)	Sep. 30, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	$ 33,323,000	$ 32,473,000
Less accumulated depreciation and amortization	(22,765,000)	(21,916,000)
Total property, plant and equipment	10,558,000	10,557,000
Land
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	7,000	7,000
Buildings
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	11,831,000	11,363,000
Machinery, equipment and tooling
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	20,648,000	20,689,000
Construction in progress
Property, Plant and Equipment [Line Items]
Property, plant and equipment, Gross	$ 837,000	$ 414,000