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Guarantees (Details) - USD ($)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Product Warranty [Abstract]    
Period of warranty 12 months  
Change in warranty accrual [Roll Forward]    
Beginning accrued product warranty $ 387,000 $ 236,000
Accruals for warranties issued 510,000 522,000
Adjustments related to pre-existing warranties including expirations and changes in estimates 186,000 227,000
Cost of warranty repair (474,000) (598,000)
Ending accrued product warranty $ 609,000 $ 387,000