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Accounts Receivable (Details 1) - USD ($)
12 Months Ended
Dec. 31, 2020
Dec. 31, 2019
Allowance for Doubtful Accounts    
Balance at Beginning of Year $ 859,000 $ 524,000
Charged to Costs and Expenses 483,000 556,000
Deductions from Reserves 378,000 221,000
Balance at End of Year $ 964,000 $ 859,000