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