Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015	Mar. 01, 2014
Significant Accounting Policies [Line Items]
Fiscal Period Duration		364 days	371 days	364 days
Cash Equivalents, at Carrying Value	$ 714	$ 341	$ 714
Allowance for Doubtful Accounts Receivable	1,455	1,946	1,455
Impairment of Long-Lived Assets Held-for-use	894	$ 0	894	$ 0
Closed stores, remaining lease term		8 months
Closed store lease liabilities	105	$ 39	105
Self Insurance, Maximum of Workers Compensation Claims Liability per Associate per Claim		2,000
Stop loss insurance specific deductible					$ 500
Stop loss insurance aggregating deductible					$ 250
Cost of Goods Sold, Vendor Allowances		114,100	123,900	97,000
Vendor Paid Cooperative Advertising Credits		19,200	19,100	17,100
Accounts Receivable, Earned Advertising Credits	852	1,000	852
Accounts Receivable, Earned Promotional Discounts	10,700	13,100	10,700
Unearned Income for Vendor Programs	$ 4,000	9,800	4,000
Advertising Expense		31,000	$ 26,300	$ 23,100
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
Maximum [Member]
Significant Accounting Policies [Line Items]
Property and Casualty Insurance, Deductible		1,000
Minimum [Member]
Significant Accounting Policies [Line Items]
Property and Casualty Insurance, Deductible		$ 100