Retirement Plans (Schedule Of Costs Of Retirement Plan) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 30, 2017	Dec. 31, 2016	Dec. 26, 2015
Defined Benefit Plan Disclosure [Line Items]
Pension Expense	$ 6,781	$ 5,574	$ 3,162
Retirement savings plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Expense	3,343	3,593	3,161
Deferred compensation plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Expense	813	788	(318)
Supplemental executive retirement plan [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Expense	1,920	909	484
Deferred compensation plan for pharmacists [Member]
Defined Benefit Plan Disclosure [Line Items]
Pension Expense	$ 705	$ 284	$ (165)