Shareholders' Equity (Reclassification out of Accumulated Other Comprehensive Income) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Interest expense	$ (5.7)	$ (6.7)
Tax impact	(12.2)	77.5
Total (income), net of tax	(35.4)	226.2
Reclassification From Accumulated Other Comprehensive Loss [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period	(1.3)	279.5
Reclassification From Accumulated Other Comprehensive Loss [Member] | Derivative Gain (Loss) [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Tax impact	0.4	0.1
Total (income), net of tax	(1.5)	(0.2)
Reclassification From Accumulated Other Comprehensive Loss [Member] | Derivative Gain (Loss) [Member] | Interest Rate Swap Contracts, Before Tax [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Interest expense	(1.9)	(0.3)
Reclassification From Accumulated Other Comprehensive Loss [Member] | Prior Service Credit Amortization [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Other non-operating (income) expense, net	(0.1)	(0.1)
Reclassification From Accumulated Other Comprehensive Loss [Member] | Amortization of Net Actuarial Loss [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Other non-operating (income) expense, net	0.4	2.3
Reclassification From Accumulated Other Comprehensive Loss [Member] | Settlement [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Other non-operating (income) expense, net		374.4
Reclassification From Accumulated Other Comprehensive Loss [Member] | Pension And Postretirement Adjustments [Member]
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Total loss, before tax	0.3	376.6
Income tax expense	(0.1)	(96.9)
Total loss, net of tax	$ 0.2	$ 279.7