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Revenue Recognition (Details) - Company`s receivables and contract liabilities with customers - USD ($)
Dec. 31, 2020
Dec. 31, 2019
Revenue Recognition (Details) - Company`s receivables and contract liabilities with customers [Line Items]    
Gross receivables $ 2,042,000 $ 3,124,000
Allowance for bad debts 660,000 743,000
Net receivables 1,382,000 2,381,000
Contract liabilities $ 618,000 $ 230,000