Revenue Recognition (Schedule Of Sales By Type Of Product) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 27, 2021	Mar. 28, 2020
Disaggregation of Revenue [Line Items]
Total net sales	$ 1,006,340	$ 985,820
Revenue Benchmark [Member] | Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 1,006,340	$ 985,820
Concentration percent	100.00%	100.00%
Grocery [Member] | Revenue Benchmark [Member] | Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 874,073	$ 863,747
Concentration percent	86.90%	87.60%
Pharmacy [Member] | Revenue Benchmark [Member] | Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 95,597	$ 89,333
Concentration percent	9.50%	9.10%
Fuel [Member] | Revenue Benchmark [Member] | Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 34,372	$ 29,967
Concentration percent	3.40%	3.00%
Manufacturing [Member] | Revenue Benchmark [Member] | Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 2,298	$ 2,773
Concentration percent	0.20%	0.30%