AOCI Attributable To Parent, After Tax [Abstract]

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AOCI Attributable To Parent, Before Tax [Abstract]

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AOCI Attributable To Parent, Tax [Abstract]

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Amount before tax and reclassification adjustments of other comprehensive income (loss) attributable to parent.

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Amount after tax, before reclassification adjustments, of other comprehensive income (loss), attributable to parent.

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Amount of tax expense (benefit) allocated to other comprehensive income (loss) before reclassification adjustment from accumulated other comprehensive income (loss).

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Amount before tax of other comprehensive income (loss) attributable to parent entity.

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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Amount of tax expense (benefit) allocated to other comprehensive income (loss) attributable to parent entity.

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Accumulated Other Comprehensive Income (Loss) (Details of Changes In Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
BEFORE TAX
Net Change	$ 46.1			$ 113.2			$ 811.7	$ 508.4
TAX EFFECT
Net Change	8.0			(44.4)			(192.5)	(145.7)
AFTER TAX
Net Change	54.1	$ 325.4	$ 239.7	68.8	$ 185.5	$ 108.4	619.2	362.7
Unrealized Gains (Losses) on Debt Securities Available for Sale
BEFORE TAX
Unrealized Gains (Losses) on Debt Securities Available for Sale	45.3			76.1			736.8	409.0
Reclassification Adjustment for (Gains) Losses Included in Net Income	0.0			0.3			(0.1)	0.6
Net Change	45.3			76.4			736.7	409.6
TAX EFFECT
Unrealized Gains (Losses) on Debt Securities Available for Sale	(11.8)			(19.4)			(185.4)	(104.6)
Reclassification Adjustment for (Gains) Losses Included in Net Income	0.0			0.0			0.0	0.0
Net Change	(11.8)			(19.4)			(185.4)	(104.6)
AFTER TAX
Unrealized Gains (Losses) on Debt Securities Available for Sale	33.5			56.7			551.4	304.4
Reclassification Adjustment for (Gains) Losses Included in Net Income	0.0			0.3			(0.1)	0.6
Net Change	33.5			57.0			551.3	305.0
Unrealized Gains (Losses) on Cash Flow Hedges
BEFORE TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	(4.7)			(4.0)			(11.2)	(21.4)
Net Change	1.7			(3.2)			7.1	(2.6)
TAX EFFECT
Reclassification Adjustment for (Gains) Losses Included in Net Income	1.2			1.0			2.8	5.3
Net Change	(0.4)			0.8			(1.8)	0.7
AFTER TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	(3.5)			(3.0)			(8.4)	(16.1)
Net Change	1.3			(2.4)			5.3	(1.9)
Foreign Currency Adjustments
BEFORE TAX
Net Change	(24.1)			34.4			24.0	73.4
TAX EFFECT
Net Change	25.9			(24.5)			5.5	(34.6)
AFTER TAX
Net Change	1.8			9.9			29.5	38.8
Foreign Currency Translation Adjustments
BEFORE TAX
Net Change	92.1			(71.9)			53.1	(69.4)
TAX EFFECT
Net Change	(3.1)			2.0			(1.0)	3.3
AFTER TAX
Net Change	89.0			(69.9)			52.1	(66.1)
Long-Term Intra-Entity Foreign Currency Transaction Gains (Losses)
BEFORE TAX
Net Change	1.2			(1.3)			0.7	(1.3)
TAX EFFECT
Net Change	(0.3)			0.3			(0.2)	0.3
AFTER TAX
Net Change	0.9			(1.0)			0.5	(1.0)
Net Investment Hedge Gains (Losses)
BEFORE TAX
Net Change	(117.4)			107.6			(29.8)	144.1
TAX EFFECT
Net Change	29.3			(26.8)			6.7	(38.2)
AFTER TAX
Net Change	(88.1)			80.8			(23.1)	105.9
Pension and Other Postretirement Benefit Adjustments
BEFORE TAX
Unrealized Gains (Losses) on Debt Securities Available for Sale	12.6			0.0			11.8	11.4
Net Change	23.2			5.6			43.9	28.0
TAX EFFECT
Unrealized Gains (Losses) on Debt Securities Available for Sale	(3.1)			0.0			(3.0)	(3.1)
Net Change	(5.7)			(1.3)			(10.8)	(7.2)
AFTER TAX
Unrealized Gains (Losses) on Debt Securities Available for Sale	9.5			0.0			8.8	8.3
Net Change	17.5			4.3			33.1	20.8
Amortization of Net Actuarial Loss
BEFORE TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	10.7			5.7			32.3	16.8
TAX EFFECT
Reclassification Adjustment for (Gains) Losses Included in Net Income	(2.6)			(1.3)			(7.8)	(4.1)
AFTER TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	8.1			4.4			24.5	12.7
Amortization of Prior Service Cost
BEFORE TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	(0.1)			(0.1)			(0.2)	(0.2)
TAX EFFECT
Reclassification Adjustment for (Gains) Losses Included in Net Income	0.0			0.0			0.0	0.0
AFTER TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	(0.1)			(0.1)			(0.2)	(0.2)
Foreign Exchange Contracts \| Unrealized Gains (Losses) on Cash Flow Hedges
BEFORE TAX
Unrealized Gains (Losses) on Debt Securities Available for Sale	6.6			0.7			18.1	17.4
TAX EFFECT
Unrealized Gains (Losses) on Debt Securities Available for Sale	(1.6)			(0.2)			(4.5)	(4.3)
AFTER TAX
Unrealized Gains (Losses) on Debt Securities Available for Sale	5.0			0.5			13.6	13.1
Interest Rate Contracts \| Unrealized Gains (Losses) on Cash Flow Hedges
BEFORE TAX
Unrealized Gains (Losses) on Debt Securities Available for Sale	(0.2)			0.1			0.2	1.4
TAX EFFECT
Unrealized Gains (Losses) on Debt Securities Available for Sale	0.0			0.0			(0.1)	(0.3)
AFTER TAX
Unrealized Gains (Losses) on Debt Securities Available for Sale	$ (0.2)			$ 0.1			$ 0.1	$ 1.1