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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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, 2021	Jun. 30, 2021	Mar. 31, 2021	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
PRE-TAX
Net Change	$ (90.9)			$ 46.1			$ (393.0)	$ 811.7
TAX
Net Change	10.2			8.0			79.0	(192.5)
AFTER TAX
Net Change	(80.7)	$ 128.8	$ (362.1)	54.1	$ 325.4	$ 239.7	(314.0)	619.2
Unrealized Gains (Losses) on Available for Sale Debt Securities
PRE-TAX
Unrealized Gains (Losses) on Available for Sale Debt Securities	(107.0)			45.3			(453.6)	736.8
Net Change	(119.7)			45.3			(481.9)	736.7
TAX
Unrealized Gains (Losses) on Available for Sale Debt Securities	26.9			(11.8)			116.4	(185.4)
Net Change	30.1			(11.8)			123.5	(185.4)
AFTER TAX
Unrealized Gains (Losses) on Available for Sale Debt Securities	(80.1)			33.5			(337.2)	551.4
Net Change	(89.6)			33.5			(358.4)	551.3
Interest Income on Debt Securities
PRE-TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	(12.7)			0.0			(28.3)	0.0
TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	3.2			0.0			7.1	0.0
AFTER TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	(9.5)			0.0			(21.2)	0.0
Net Gains on Debt Securities
PRE-TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	0.0			0.0			0.0	(0.1)
TAX
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	0.0			0.0			0.0	(0.1)
Unrealized Gains (Losses) on Cash Flow Hedges
PRE-TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	0.7			(4.7)			(4.0)	(11.2)
Net Change	6.2			1.7			3.2	7.1
TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	(0.2)			1.2			1.0	2.8
Net Change	(1.6)			(0.4)			(0.8)	(1.8)
AFTER TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	0.5			(3.5)			(3.0)	(8.4)
Net Change	4.6			1.3			2.4	5.3
Foreign Currency Adjustments
PRE-TAX
Net Change	22.1			(24.1)			45.7	24.0
TAX
Net Change	(18.3)			25.9			(34.8)	5.5
AFTER TAX
Net Change	3.8			1.8			10.9	29.5
Foreign Currency Translation Adjustments
PRE-TAX
Net Change	(64.5)			92.1			(111.7)	53.1
TAX
Net Change	3.5			(3.1)			4.8	(1.0)
AFTER TAX
Net Change	(61.0)			89.0			(106.9)	52.1
Long-Term Intra-Entity Foreign Currency Transaction Gains (Losses)
PRE-TAX
Net Change	(0.1)			1.2			0.1	0.7
TAX
Net Change	0.0			(0.3)			(0.1)	(0.2)
AFTER TAX
Net Change	(0.1)			0.9			0.0	0.5
Net Investment Hedge Gains (Losses)
PRE-TAX
Net Change	86.7			(117.4)			157.3	(29.8)
TAX
Net Change	(21.8)			29.3			(39.5)	6.7
AFTER TAX
Net Change	64.9			(88.1)			117.8	(23.1)
Pension and Other Postretirement Benefit Adjustments
PRE-TAX
Unrealized Gains (Losses) on Available for Sale Debt Securities	(15.5)			12.6			(17.2)	11.8
Net Change	0.5			23.2			40.0	43.9
TAX
Unrealized Gains (Losses) on Available for Sale Debt Securities	3.9			(3.1)			5.1	(3.0)
Net Change	0.0			(5.7)			(8.9)	(10.8)
AFTER TAX
Unrealized Gains (Losses) on Available for Sale Debt Securities	(11.6)			9.5			(12.1)	8.8
Net Change	0.5			17.5			31.1	33.1
Amortization of Net Actuarial Loss
PRE-TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	16.2			10.7			58.0	32.3
TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	(4.0)			(2.6)			(14.2)	(7.8)
AFTER TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	12.2			8.1			43.8	24.5
Amortization of Prior Service Cost
PRE-TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	(0.2)			(0.1)			(0.8)	(0.2)
TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	0.1			0.0			0.2	0.0
AFTER TAX
Reclassification Adjustment for (Gains) Losses Included in Net Income	(0.1)			(0.1)			(0.6)	(0.2)
Foreign Exchange Contracts \| Unrealized Gains (Losses) on Cash Flow Hedges
PRE-TAX
Unrealized Gains (Losses) on Available for Sale Debt Securities	5.5			6.6			7.2	18.1
TAX
Unrealized Gains (Losses) on Available for Sale Debt Securities	(1.4)			(1.6)			(1.8)	(4.5)
AFTER TAX
Unrealized Gains (Losses) on Available for Sale Debt Securities	4.1			5.0			5.4	13.6
Interest Rate Contracts \| Unrealized Gains (Losses) on Cash Flow Hedges
PRE-TAX
Unrealized Gains (Losses) on Available for Sale Debt Securities	0.0			(0.2)			0.0	0.2
TAX
Unrealized Gains (Losses) on Available for Sale Debt Securities	0.0			0.0			0.0	(0.1)
AFTER TAX
Unrealized Gains (Losses) on Available for Sale Debt Securities	$ 0.0			$ (0.2)			$ 0.0	$ 0.1