Retirement Benefits (Details1) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Pension Plans Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost - benefits earned during the year	$ 3.5	$ 5.2	$ 10.5	$ 15.5
Interest cost on benefits earned in prior years	29.2	31.4	87.6	94.1
Expected return on plan assets	(36.7)	(37.2)	(110.1)	(111.5)
Amortization of prior service cost (credit)	0.3	0.3	0.9	0.9
Amortization of net actuarial loss	15.6	16.3	46.9	49.0
Total retirement benefit expense	11.9	16.0	35.8	48.0
Other Postretirement Benefit Plan, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost - benefits earned during the year	0.6	0.6	1.8	1.9
Interest cost on benefits earned in prior years	3.7	4.0	11.0	12.0
Expected return on plan assets	0.0	0.0	0.0	0.0
Amortization of prior service cost (credit)	(0.7)	(0.7)	(2.1)	(0.9)
Amortization of net actuarial loss	2.2	2.4	6.7	7.2
Total retirement benefit expense	$ 5.8	$ 6.3	$ 17.4	$ 20.2