Retirement Benefits (Components Of Net Periodic (Benefit Credit) Benefit Cost) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 2.5	$ 2.8
Interest cost	16.6	17.3
Expected return on assets	(36.8)	(36.7)
Recognized actuarial loss	5.4	4.4
Settlement loss	1.7	2.4
Amortization of prior service credit	(0.1)	(0.1)
Net periodic benefit credit	(10.7)	(9.9)
Other Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Service cost	0.3	0.4
Interest cost	5.2	5.6
Expected return on assets	(5.7)	(5.6)
Recognized actuarial loss	2.9	3.1
Settlement loss	0.0	0.0
Amortization of prior service credit	(3.4)	(3.5)
Net periodic benefit credit	$ (0.7)	$ 0.0