Other Comprehensive Income (Loss) (Reclassification) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other–net, (income) expense	$ (122.7)	$ (86.0)
Total before tax	(1,679.9)	(731.1)
Tax benefit	223.4	170.0
Reclassifications from continuing operations (net of tax)	(1,456.5)	(561.1)
Reclassifications from discontinued operations (net of tax)	0.0	(3,680.5)
Net of tax	80.5	133.4
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications from continuing operations (net of tax)	80.5	49.4
Reclassifications from discontinued operations (net of tax)	0.0	84.0
Net of tax	80.5	133.4
Retirement benefit items | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax	98.0	55.9
Tax benefit	(20.6)	(11.2)
Net of tax	77.4	44.7
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	(13.8)	(14.2)
Actuarial losses, net | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other–net, (income) expense	111.8	70.1
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	$ 3.1	$ 4.7