Revenue Recognition (Schedule Of Sales By Type Of Product) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 27, 2020	Jun. 29, 2019	Jun. 27, 2020	Jun. 29, 2019
Disaggregation of Revenue [Line Items]
Total net sales	$ 1,098,704	$ 887,967	$ 2,084,524	$ 1,764,686
Revenue Benchmark [Member] | Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 1,098,704	$ 887,967	$ 2,084,524	$ 1,764,686
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	$ 987,502	$ 767,886	$ 1,851,249	$ 1,534,787
Concentration percent	89.90%	86.60%	88.90%	87.00%
Pharmacy [Member] | Revenue Benchmark [Member] | Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 85,808	$ 84,682	$ 175,142	$ 166,463
Concentration percent	7.80%	9.50%	8.40%	9.40%
Fuel [Member] | Revenue Benchmark [Member] | Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 23,129	$ 33,271	$ 53,096	$ 59,736
Concentration percent	2.10%	3.70%	2.50%	3.40%
Manufacturing [Member] | Revenue Benchmark [Member] | Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 2,265	$ 2,128	$ 5,037	$ 3,700
Concentration percent	0.20%	0.20%	0.20%	0.20%