Retirement Benefits (Details1) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Pension Plans Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost - benefits earned during the year	$ 3.1	$ 4.0	$ 6.3	$ 8.2
Interest cost on benefits earned in prior years	26.4	26.3	52.7	52.4
Expected return on plan assets	(32.9)	(39.5)	(65.7)	(79.0)
Amortization of prior service cost (credit)	0.1	0.1	0.2	0.2
Amortization of net actuarial loss	18.4	16.5	36.8	33.0
Curtailment loss	0.0	0.4	0.0	0.4
Total retirement benefit expense	15.1	7.8	30.3	15.2
Other Postretirement Benefit Plan, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost - benefits earned during the year	0.4	0.6	0.9	1.2
Interest cost on benefits earned in prior years	3.7	3.2	7.4	6.3
Expected return on plan assets	0.0	0.0	0.0	0.0
Amortization of prior service cost (credit)	(0.7)	(0.7)	(1.4)	(1.4)
Amortization of net actuarial loss	3.4	2.6	6.7	5.3
Curtailment loss	0.0	0.0	0.0	0.0
Total retirement benefit expense	$ 6.8	$ 5.7	$ 13.6	$ 11.4