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Summary Of Significant Accounting Policies (Narrative) (Details) - USD ($) | 3 Months Ended | 12 Months Ended |
--- | --- | --- | ---
Dec. 31, 2016 | Dec. 29, 2018 | Dec. 30, 2017 | Dec. 31, 2016 | Mar. 01, 2014
Significant Accounting Policies [Line Items] |  |  |  |  |
Cumulative Effect of New Accounting Principle in Period of Adoption | $ 0 |  | $ 0 | $ 0 |
Fiscal Period Duration |  | 364 days | 364 days | 371 days |
Cash Equivalents, at Carrying Value |  | $ 5,400,000 | $ 341,000 |  |
Allowance for Doubtful Accounts Receivable |  | 2,100,000 | 1,900,000 |  |
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months |  | 1,017,000 |  |  |
Finite-Lived Intangible Assets, Amortization Expense, Year Two |  | 979,000 |  |  |
Finite-Lived Intangible Assets, Amortization Expense, Year Three |  | 921,000 |  |  |
Finite-Lived Intangible Assets, Amortization Expense, Year Four |  | 673,000 |  |  |
Finite-Lived Intangible Assets, Amortization Expense, Year Five |  | 526,000 |  |  |
Impairment of Long-Lived Assets Held-for-use | $ 894,000 | 1,532,000 | 0 | $ 894,000 |
Closed store lease liabilities |  | 0 | 39,000 |  |
Self Insurance, Maximum of Workers Compensation Claims Liability per Associate per Claim |  | 2,000,000 |  |  |
Stop loss insurance specific deductible |  |  |  |  | $ 500,000
Stop loss insurance aggregating deductible |  |  |  |  | $ 250,000
Cost of Goods Sold, Vendor Allowances |  | 132,000,000 | 131,100,000 | 141,600,000 |
Vendor Paid Cooperative Advertising Credits |  | 19,400,000 | 19,200,000 | $ 19,100,000 |
Accounts Receivable, Earned Advertising Credits |  | 1,600,000 | 1,000,000 |  |
Accounts Receivable, Earned Promotional Discounts |  | 12,000,000 | 13,100,000 |  |
Unearned Income for Vendor Programs |  | 7,400,000 | 9,800,000 |  |
Accounting Standards Update 2016-01 [Member] |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income |  | (1,600,000) |  |  |
Cumulative Effect of New Accounting Principle in Period of Adoption |  |  | $ 5,500,000 |  |
Unrealized loss in value of equity securities |  | 1,600,000 |  |  |
Accounting Standards Update 2016-02 [Member] |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
New Accounting Pronouncement or Change in Accounting Principle, Effect of Change on Net Income |  | 0 |  |  |
Cumulative Effect of New Accounting Principle in Period of Adoption |  | (210,000,000) |  |  |
Between March 1, 2013 to March 1, 2014 [Member] |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Self Insurance, Annual Maximum of Health Claims Liability per Associate |  | 2,000,000 |  |  |
Maximum [Member] |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Property and Casualty Insurance, Deductible |  | 1,000,000 |  |  |
Minimum [Member] |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Property and Casualty Insurance, Deductible |  | $ 100,000 |  |  |
Lease Acquisitions [Member] | Maximum [Member] |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Finite-Lived Intangible Asset, Useful Life |  | 30 years |  |  |
Customer Lists [Member] | Maximum [Member] |  |  |  |  |
Significant Accounting Policies [Line Items] |  |  |  |  |
Finite-Lived Intangible Asset, Useful Life |  | 10 years |  |  |

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