Retirement Plans (Summary of Net Pension and Supplemental Executive Retirement Plan Expense Recognized) (Details) - USD ($) $ in Millions	3 Months Ended		8 Months Ended
	Sep. 10, 2016	Sep. 12, 2015	Sep. 10, 2016	Sep. 12, 2015
Compensation and Retirement Disclosure [Abstract]
Service cost pertaining to benefits earned during the period	$ 1.5	$ 2.1	$ 4.5	$ 6.3
Interest cost on projected benefit obligations	4.5	4.2	13.3	12.7
Expected return on pension assets	(4.6)	(4.7)	(13.9)	(14.2)
Net amortization loss	1.1	4.8	3.4	14.5
Net pension expense	$ 2.5	$ 6.4	$ 7.3	$ 19.3