Business Description and Summary of Significant Accounting Policies - Additional Information (Details)	3 Months Ended
	Mar. 31, 2021 USD ($) Y	Mar. 31, 2020 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Allowance for doubtful accounts	$ 224,000		$ 188,000
Warranty period	27 months
Inventory reserve	$ 1,777,000		$ 1,720,000	$ 1,720,000
Income taxes paid	$ 51,000	$ 42,000
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