Defined Benefit Plans (Components of Net Periodic Benefit Cost of Other Postretirement Benefit Pension Pans) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 30, 2018	Mar. 31, 2017
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ (10.9)	$ (9.8)
Net periodic benefit cost	(3.1)	(2.9)
Other postretirement benefit plans
Defined Benefit Plan Disclosure [Line Items]
Service cost	(0.1)	(0.2)
Interest cost	(1.2)	(1.3)
Amortization of prior service credit	(0.6)	(0.8)
Net periodic benefit cost	$ (0.7)	$ (0.7)