Retirement Benefits (Details1) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Settlement gain	$ (64.9)	$ 0.0	$ (64.9)	$ 0.0
Pension Plans Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost - benefits earned during the year	3.8	3.2	11.3	9.5
Interest cost on benefits earned in prior years	17.1	21.6	51.3	64.7
Expected return on plan assets	(34.1)	(33.6)	(102.3)	(100.8)
Amortization of prior service cost (credit)	0.2	0.1	0.5	0.5
Amortization of net actuarial loss	18.9	18.6	56.7	55.8
Settlement gain	0.0	0.0	0.0	0.0
Total retirement benefit expense (income)	5.9	9.9	17.5	29.7
Other Postretirement Benefit Plan, Defined Benefit
Defined Benefit Plan Disclosure [Line Items]
Service cost - benefits earned during the year	0.4	0.6	1.1	1.7
Interest cost on benefits earned in prior years	1.9	2.6	6.1	8.0
Expected return on plan assets	0.0	0.0	0.0	0.0
Amortization of prior service cost (credit)	(0.6)	(0.9)	(1.9)	(2.8)
Amortization of net actuarial loss	3.6	2.7	10.2	8.1
Settlement gain	(64.9)	0.0	(64.9)	0.0
Total retirement benefit expense (income)	$ (59.6)	$ 5.0	$ (49.4)	$ 15.0