Retirement Plans (Summary of Net Pension and Supplemental Executive Retirement Plan Expense Recognized) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 26, 2020	Sep. 28, 2019	Sep. 26, 2020	Sep. 28, 2019
Retirement Benefits [Abstract]
Service cost pertaining to benefits earned during the period	$ 1.6	$ 1.3	$ 4.8	$ 4.1
Interest cost on projected benefit obligations	3.6	3.8	10.7	11.4
Expected return on pension assets	(4.7)	(4.4)	(14.0)	(13.3)
Net amortization loss	1.6	0.7	4.9	2.0
Net pension expense	$ 2.1	$ 1.4	$ 6.4	$ 4.2