Accumulated Other Comprehensive Loss (Reclassifications Out Of Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Non-operating expenses	$ 25.3			$ 5.9			$ 41.4	$ 18.8
Tax benefit	11.8			17.9			34.0	48.7
Total reclassifications for the period, net of tax	(34.6)	$ (37.1)	$ (21.5)	(49.0)	$ (47.0)	$ (34.4)	(93.2)	(130.4)
Reclassification out of AOCI
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Non-operating expenses	25.3			4.8			40.4	14.5
Tax benefit	(6.5)			(1.2)			(10.4)	(3.7)
Total reclassifications for the period, net of tax	18.8			3.6			30.0	10.8
Reclassification out of AOCI | Actuarial Losses Recognized
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Non-operating expenses	25.3			4.8			40.4	14.5
Tax benefit	(6.5)			(1.2)			(10.4)	(3.7)
Total reclassifications for the period, net of tax	$ 18.8			$ 3.6			$ 30.0	$ 10.8