Pension and Other Postretirement Benefit Plans - Components of Net Periodic Expense (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Other Postretirement Benefits Plan [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Service Cost		$ 3.0	$ 3.6	$ 3.3
Interest Cost	[1]	4.4	4.4	5.0
Expected Return on Plan Assets	[1]	(9.6)	(9.9)	(9.7)
Amortization of Loss	[1]	0.4	3.0	1.0
Amortization of Prior Service Cost	[1]	(7.5)	(7.6)	(8.0)
Effect of Plan Curtailment	[1]	0.0	0.0	(0.3)
Net Pension Cost		(9.3)	(6.5)	(8.7)
Pension [Member]
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Service Cost		9.3	11.0	10.7
Interest Cost	[2]	27.2	24.6	27.9
Expected Return on Plan Assets	[2]	(41.5)	(43.4)	(42.7)
Amortization of Loss	[2]	11.4	18.8	12.8
Amortization of Prior Service Cost	[2]	(0.1)	(0.2)	(0.2)
Net Pension Cost		$ 6.3	$ 10.8	$ 8.5

[1] These components of net periodic postretirement health and life cost are included in the line item “Other” under Other Income (Expense) on the Consolidated Statement of Income.

[2] These components of net periodic pension cost are included in the line item “Other” under Other Income (Expense) on the Consolidated Statement of Income.