Cash And Cash Equivalents And Advertising Accounting Policies (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Sep. 29, 2018	Sep. 30, 2017	Dec. 30, 2017	Dec. 31, 2016
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents	$ 38,312	$ 42,436	$ 38,312	$ 42,436	$ 47,917	$ 46,818
Accounts receivable, net	56,102		56,102		56,265
Advertising Expense	3,600	3,200	8,000	10,100
Cost of sales, including advertising, warehousing and distribution expenses	636,736	634,652	1,908,740	1,900,655
Credit Card Receivable [Member]
Cash and Cash Equivalents [Line Items]
Accounts receivable, net	$ 22,700		$ 22,700		26,600
Reclassifications [Member]
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents		22,282		22,282	26,612	$ 32,165
Accounts receivable, net					$ (26,612)
Cost of sales, including advertising, warehousing and distribution expenses		$ 3,230		$ 10,110