Other Comprehensive Income (Loss) (Schedule of Reclassifications Out of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other, net (income) expense	$ (1,246.7)	$ (344.6)	$ 11.7
Total before tax	(7,229.9)	(5,265.9)	(3,680.1)
Income taxes	1,036.2	628.0	529.5
Reclassifications from continuing operations (net of tax)	(6,193.7)	(4,637.9)	(3,150.6)
Reclassifications from discontinued operations (net of tax)	0.0	(3,680.5)	(81.4)
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications from continuing operations (net of tax)	283.4	130.2	188.4
Reclassifications from discontinued operations (net of tax)	0.0	84.0	2.1
Total reclassifications for the period, net of tax	283.4	214.2	190.5
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	338.3	230.0	263.7
Income taxes	(71.0)	(48.3)	(55.8)
Total reclassifications for the period, net of tax	267.3	181.7	207.9
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	(55.0)	(56.8)	(74.9)
Actuarial losses | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other, net (income) expense	393.3	286.8	338.6
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	$ (51.5)	$ (19.5)