Other Comprehensive Income (Loss) (Reclassification) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other–net, (income) expense	$ (13.2)	$ (23.6)	$ (11.0)	$ 35.7
Total before tax	2,088.9	1,090.9	3,618.6	3,144.5
Tax benefit	(325.7)	(138.4)	(510.5)	(289.1)
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total reclassifications, net of tax	15.3	60.0	5.8	121.3
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	16.3	71.7	32.8	145.9
Tax benefit	(3.4)	(15.0)	(6.9)	(30.6)
Total reclassifications, net of tax	12.9	56.7	25.9	115.3
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	(12.6)	(13.1)	(25.2)	(26.1)
Actuarial losses, net | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other–net, (income) expense	28.9	84.8	58.0	172.0
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	$ 2.4	$ 3.3	$ (20.1)	$ 6.0