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Retirement Plans (Summary of Net Pension and Supplemental Executive Retirement Plan Expense Recognized) (Details) - USD ($)
$ in Millions
3 Months Ended
Apr. 01, 2017
Mar. 26, 2016
Compensation and Retirement Disclosure [Abstract]    
Service cost pertaining to benefits earned during the period $ 1.8 $ 1.5
Interest cost on projected benefit obligations 4.4 4.4
Expected return on pension assets (4.9) (4.6)
Net amortization loss 2.4 1.1
Net pension expense $ 3.7 $ 2.4