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Revenue Recognition (Details) - Company`s receivables and contract liabilities with customers - USD ($)
Jun. 30, 2021
Dec. 31, 2020
Revenue Recognition (Details) - Company`s receivables and contract liabilities with customers [Line Items]    
Gross receivables $ 2,297,000 $ 2,042,000
Allowance for bad debts 474,000 660,000
Net receivables 1,823,000 1,382,000
Contract liabilities $ 481,000 $ 618,000