Summary of Significant Accounting Policies (Details)	12 Months Ended
Dec. 31, 2020 USD ($) segment	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)
Property, Plant and Equipment
Number of reporting segments \| segment	2
Cash and cash equivalents	$ 7,564,000	$ 14,178,000
Impairments of long lived assets	0	0	$ 0
Goodwill impairment	0	0	0
Impairment of finite lived intangible assets	0	0	0
Product warranty reserve	1,249,000	1,222,000
Foreign currency transaction loss	(32,000)	202,000	(483,000)
Research and development expenses	$ 2,643,000	2,614,000	$ 2,646,000
Buildings \| Minimum
Property, Plant and Equipment
Property, plant and equipment useful life	7 years
Buildings \| Maximum
Property, Plant and Equipment
Property, plant and equipment useful life	40 years
Machinery and equipment \| Minimum
Property, Plant and Equipment
Property, plant and equipment useful life	2 years
Machinery and equipment \| Maximum
Property, Plant and Equipment
Property, plant and equipment useful life	50 years
Leasehold improvements \| Minimum
Property, Plant and Equipment
Property, plant and equipment useful life	7 years
Leasehold improvements \| Maximum
Property, Plant and Equipment
Property, plant and equipment useful life	19 years
Non Domestic
Property, Plant and Equipment
Cash and cash equivalents	$ 6,995,000	13,660,000
Bank term deposits	$ 18,000	$ 17,000

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

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