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Income Taxes (Narrative) (Details) - USD ($) $ in Thousands | Dec. 26, 2018 | Dec. 27, 2017
--- | --- | ---
Valuation Allowance [Line Items] |  |
Tax credit carryforward | $ 11,061 | $ 13,355
Alternative minimum tax credit carryforwards | 928 | 3,534
Valuation allowance | 13,199 | $ 13,078
General Business Tax Credit Carryforward [Member] |  |
Valuation Allowance [Line Items] |  |
Tax credit carryforward | 7,400 |
South Carolina NOL Carryforwards [Member] |  |
Valuation Allowance [Line Items] |  |
Valuation allowance | $ 11,800 |

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