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Commitments And Contingencies (Narrative) (Details) - USD ($) |  | 12 Months Ended
--- | --- | ---
Oct. 01, 2020 | Dec. 31, 2020
James J. Cotter, Jr., Derivative Litigation [Member] |  |
Commitments And Contingencies [Line Items] |  |
Damages sought | $ 809,000 |
Employment Litigation [Member] |  |
Commitments And Contingencies [Line Items] |  |
Insurance deductible |  | $ 150,000
Class B [Member] | Cotter Estate [Member] | Cotter, Jr. Related Litigation Matters [Member] |  |
Commitments And Contingencies [Line Items] |  |
Shares held by estate |  | 427,808
Voting stock percent |  | 25.50%
Class B [Member] | Cotter Trust [Member] | Cotter, Jr. Related Litigation Matters [Member] |  |
Commitments And Contingencies [Line Items] |  |
Shares held by estate |  | 696,080
Voting stock percent |  | 41.40%
Class B [Member] | Cotter Voting Trust [Member] | Cotter, Jr. Related Litigation Matters [Member] |  |
Commitments And Contingencies [Line Items] |  |
Shares held by estate |  | 1,123,888
Voting stock percent |  | 66.90%

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