Other Comprehensive Income (Loss) (Schedule of Reclassifications Out of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other, net (income) expense	$ (32.7)	$ (14.3)	$ 51.4
Total before tax	6,554.6	6,806.4	6,155.5
Tax benefit	(1,314.2)	(561.6)	(573.8)
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications for the period, net of tax	35.8	250.8	357.9
Amortization of retirement benefit items | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	65.7	290.9	435.5
Tax benefit	(13.8)	(61.1)	(91.5)
Total reclassifications for the period, net of tax	51.9	229.8	344.0
Prior service benefits, net | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other, net (income) expense	(50.5)	(52.4)	(55.4)
Actuarial losses | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other, net (income) expense	116.2	343.3	490.9
Other, net of tax | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other, net (income) expense	$ (16.1)	$ 21.0	$ 13.9