Revenue Recognition (Schedule Of Sales By Type Of Product) (Details) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 29, 2019 USD ($)	Jun. 30, 2018 USD ($)	Jun. 29, 2019 USD ($) segment	Jun. 30, 2018 USD ($)
Disaggregation of Revenue [Line Items]
Number of reportable segments \| segment			1
Total net sales	$ 887,967	$ 871,100	$ 1,764,686	$ 1,747,206
Revenue Benchmark [Member] \| Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 887,967	$ 871,100	$ 1,764,686	$ 1,747,206
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	$ 767,886	$ 757,894	$ 1,534,787	$ 1,525,912
Concentration percent	86.60%	87.00%	87.00%	87.30%
Pharmacy [Member] \| Revenue Benchmark [Member] \| Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 84,682	$ 78,271	$ 166,463	$ 156,211
Concentration percent	9.50%	9.00%	9.40%	8.90%
Fuel [Member] \| Revenue Benchmark [Member] \| Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 33,271	$ 33,439	$ 59,736	$ 62,084
Concentration percent	3.70%	3.80%	3.40%	3.60%
Manufacturing [Member] \| Revenue Benchmark [Member] \| Product Concentration Risk [Member]
Disaggregation of Revenue [Line Items]
Total net sales	$ 2,128	$ 1,496	$ 3,700	$ 2,999
Concentration percent	0.20%	0.20%	0.20%	0.20%

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

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