Revenue Recognition (Schedule Of Sales By Type Of Product) (Details) $ in Thousands	3 Months Ended			9 Months Ended
	Sep. 28, 2019 USD ($)	Sep. 29, 2018 USD ($)		Sep. 28, 2019 USD ($) segment	Sep. 29, 2018 USD ($)
Disaggregation of Revenue [Line Items]
Number of reportable segments | segment				1
Total net sales	$ 876,222	$ 869,076		$ 2,640,907	$ 2,616,282
Revenue Benchmark [Member] | Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 876,222	$ 869,076	[1]	$ 2,640,907	$ 2,616,282	[1]
Concentration percent	100.00%	100.00%	[1]	100.00%	100.00%	[1]
Revenue Benchmark [Member] | Product Concentration Risk [Member] | Reclass Between Manufacturing And Grocery [Member]
Disaggregation of Revenue [Line Items]
Total net sales		$ 13,400			$ 39,300
Concentration percent		1.60%			1.50%
Grocery [Member] | Revenue Benchmark [Member] | Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 754,872	$ 756,578	[1]	$ 2,289,658	$ 2,282,490	[1]
Concentration percent	86.10%	87.10%	[1]	86.70%	87.20%	[1]
Pharmacy [Member] | Revenue Benchmark [Member] | Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 84,632	$ 77,568	[1]	$ 251,095	$ 233,778	[1]
Concentration percent	9.70%	8.90%	[1]	9.50%	8.90%	[1]
Fuel [Member] | Revenue Benchmark [Member] | Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 34,041	$ 33,668	[1]	$ 93,777	$ 95,751	[1]
Concentration percent	3.90%	3.90%	[1]	3.60%	3.70%	[1]
Manufacturing [Member] | Revenue Benchmark [Member] | Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 2,677	$ 1,262	[1]	$ 6,377	$ 4,263	[1]
Concentration percent	0.30%	0.10%	[1]	0.20%	0.20%	[1]

[1] The Company reclassified net sales amounts between manufacturing and grocery relating to the Company's 10-Q filed November, 2018. For the thirteen weeks ended September 29, 2018, the Company presents the amounts above with $13.4 million, or 1.6% of net sales, as a reclass between manufacturing and grocery. For the thirty-nine weeks ended September 29, 2018, the Company presents the amounts above with $39.3 million, or 1.5% of net sales, as a reclass between manufacturing and grocery.