Revenue Recognition (Schedule Of Sales By Type Of Product) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 26, 2020	Sep. 28, 2019	Sep. 26, 2020	Sep. 28, 2019
Disaggregation of Revenue [Line Items]
Total net sales	$ 1,002,387	$ 876,222	$ 3,086,910	$ 2,640,907
Revenue Benchmark [Member] | Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 1,002,387	$ 876,222	$ 3,086,910	$ 2,640,907
Concentration percent	100.00%	100.00%	100.00%	100.00%
Grocery [Member] | Revenue Benchmark [Member] | Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 878,378	$ 754,872	$ 2,729,626	$ 2,289,658
Concentration percent	87.70%	86.10%	88.40%	86.70%
Pharmacy [Member] | Revenue Benchmark [Member] | Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 89,306	$ 84,632	$ 264,448	$ 251,095
Concentration percent	8.90%	9.70%	8.60%	9.50%
Fuel [Member] | Revenue Benchmark [Member] | Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 32,275	$ 34,041	$ 85,370	$ 93,777
Concentration percent	3.20%	3.90%	2.80%	3.60%
Manufacturing [Member] | Revenue Benchmark [Member] | Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 2,428	$ 2,677	$ 7,466	$ 6,377
Concentration percent	0.20%	0.30%	0.20%	0.20%