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Critical Accounting Policies and Estimates (Details) - USD ($)
 3 Months Ended
Mar. 31, 2021
Mar. 31, 2020
Dec. 31, 2020
Unusual or Infrequent Item, or Both [Line Items]      
Allowance for doubtful accounts $ 51,000   $ 41,000
Accounts receivable for chargebacks 402,000   179,000
Allowance for slow moving and obsolete inventory 451,000   546,000
Recorded contract assets 549,000   554,000
Amount of revenue from contract liabilities related to open jobs outstanding 2,710,000    
Impairment of long-lived assets 0 $ 0  
Estimated liability for compensation claims 763,000   933,000
Liability for post retirement healthcare benefits 9,048,000   $ 9,109,000
Contract-based intangible assets      
Unusual or Infrequent Item, or Both [Line Items]      
Impairment on contract assets $ 0