Retirement Benefits (Details 1) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Defined Contribution Plan, Cost	$ 35.5	$ 34.5	$ 41.2
Pension Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Curtailment	0.0	6.7
Service cost - benefits earned during the year	14.1	20.6	22.8
Interest cost on benefits earned in prior years	116.7	125.4	121.0
Expected return on plan assets	(146.9)	(148.7)	(168.3)
Amortization of prior service cost (credit)	1.3	1.3	1.3
Amortization of net actuarial loss	62.6	65.4	60.4
Plan amendments	0.0	0.0
Termination benefits	0.0	1.1	0.0
Total retirement benefit expense	47.8	65.1	37.2
Other Postretirement Benefits [Member]
Defined Benefit Plan Disclosure [Line Items]
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Curtailment	0.0	0.0
Defined Contribution Plan, Cost	1.7
Service cost - benefits earned during the year	2.4	2.6	2.7
Interest cost on benefits earned in prior years	14.6	16.0	17.9
Expected return on plan assets	0.0	(0.1)	(0.1)
Amortization of prior service cost (credit)	(2.9)	(1.7)	4.9
Amortization of net actuarial loss	9.0	9.6	14.6
Plan amendments	0.0	(22.5)
Termination benefits	0.0	2.3	0.0
Total retirement benefit expense	$ 23.1	$ 28.7	$ 40.0