Pension and Other Postretirement Benefit Plans (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Pension [Member]
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service Cost		$ 2.6	$ 2.3
Interest Cost	[1]	7.0	8.0
Expected Return on Plan Assets	[1]	(10.7)	(11.0)
Amortization of Prior Service Credits	[1]	0.0	0.0
Amortization of Net Loss	[1]	3.2	1.8
Net Periodic Benefit Cost (Credit)		2.1	1.1
Employer Contributions to Defined Benefit Plans		10.7	10.4
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year		0.0
Other Postretirement [Member]
Components of Net Periodic Benefit Cost (Credit) [Abstract]
Service Cost		0.8	1.0
Interest Cost	[1]	1.3	1.9
Expected Return on Plan Assets	[1]	(2.5)	(2.6)
Amortization of Prior Service Credits	[1]	(2.0)	(0.4)
Amortization of Net Loss	[1]	0.3	0.1
Net Periodic Benefit Cost (Credit)		(2.1)	0.0
Employer Contributions to Defined Benefit Plans		0.0	$ 0.0
Defined Benefit Plan, Expected Future Employer Contributions, Remainder of Fiscal Year		$ 0.0

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