Other Comprehensive Income (Loss) (Schedule of Reclassifications Out of Accumulated Other Comprehensive Loss) (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other, net (income) expense									$ (344.6)	$ 11.7	$ (111.1)
Total before tax									(5,265.9)	(3,680.1)	(2,304.8)
Income taxes	$ 167.4	$ 151.9	$ 138.7	$ 170.0	$ (189.8)	$ 247.5	$ 273.3	$ 198.5	628.0	529.5	2,391.2
Reclassifications from continuing operations (net of tax)	(1,495.7)	(1,253.9)	(1,327.2)	(561.1)	(1,121.4)	(1,093.6)	231.6	(1,167.2)	(4,637.9)	(3,150.6)	86.4
Reclassifications from discontinued operations (net of tax)	0.0	0.0	0.0	(3,680.5)	(3.7)	(55.9)	28.3	(50.2)	(3,680.5)	(81.4)	117.7
Net of tax	$ (1,495.7)	$ (1,253.9)	$ (1,327.2)	$ (4,241.6)	$ (1,125.1)	$ (1,149.5)	$ 259.9	$ (1,217.4)
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Reclassifications from continuing operations (net of tax)									130.2	188.4	59.0
Reclassifications from discontinued operations (net of tax)									84.0	2.1	1.5
Net of tax									214.2	190.5	60.5
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									230.0	263.7	220.8
Income taxes									(48.3)	(55.8)	(68.9)
Net of tax									181.7	207.9	151.9
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									(56.8)	(74.9)	(84.4)
Actuarial losses | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other, net (income) expense									286.8	338.6	305.2
Unrealized gains/losses on available-for-sale securities | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other, net (income) expense									(2.4)	(39.5)	(170.2)
Income taxes									0.5	8.3	59.6
Net of tax									(1.9)	(31.2)	(110.6)
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									$ (49.6)	$ 11.7	$ 17.7