Business Description and Summary of Significant Accounting Policies - Additional Information (Details)	9 Months Ended
	Sep. 30, 2021 USD ($) Y	Sep. 30, 2020 USD ($)	Dec. 31, 2020 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for doubtful accounts	$ 154,000		$ 188,000
Warranty period	27 months
Warranty reserve	$ 396,000		382,000
Inventory reserve	1,645,000		$ 1,720,000
Income taxes paid	345,000	$ 425,000
Interest paid	$ 110,000	$ 116,000
Minimum
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Period inventory is expected to be used	1 year
Number of years of customer requirements | Y	2
Number of year's supply | Y	1