Accumulated Other Comprehensive Income (Loss) (Details of Changes In Accumulated Other Comprehensive Income (Loss)) (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025
AOCI Attributable To Parent, Before Tax [Abstract]
Net Change	$ (45.1)	$ 72.2
AOCI Attributable To Parent, Tax [Abstract]
Net Change	(1.0)	2.3
AOCI Attributable To Parent, After Tax [Abstract]
Other Comprehensive Income (Loss)	(46.1)	74.5
Available for Sale Debt Securities
AOCI Attributable To Parent, Before Tax [Abstract]
Gains (Losses)	(86.2)	71.2
Net Change	(61.7)	96.0
AOCI Attributable To Parent, Tax [Abstract]
Gains (Losses)	23.1	(18.9)
Net Change	17.1	(25.0)
AOCI Attributable To Parent, After Tax [Abstract]
Gains (Losses)	(63.1)	52.3
Other Comprehensive Income (Loss)	(44.6)	71.0
Interest Income on Debt Securities
AOCI Attributable To Parent, Before Tax [Abstract]
Reclassification Adjustments for (Gains) Losses Included in Net Income	24.5	24.8
AOCI Attributable To Parent, Tax [Abstract]
Reclassification Adjustments for (Gains) Losses Included in Net Income	(6.0)	(6.1)
AOCI Attributable To Parent, After Tax [Abstract]
Reclassification Adjustments for (Gains) Losses Included in Net Income	18.5	18.7
Unrealized Gains (Losses) on Cash Flow Hedges
AOCI Attributable To Parent, Before Tax [Abstract]
Reclassification Adjustments for (Gains) Losses Included in Net Income	(13.4)	(10.5)
Net Change	(7.1)	(0.7)
AOCI Attributable To Parent, Tax [Abstract]
Reclassification Adjustments for (Gains) Losses Included in Net Income	4.2	2.6
Net Change	1.8	0.2
AOCI Attributable To Parent, After Tax [Abstract]
Reclassification Adjustments for (Gains) Losses Included in Net Income	(9.2)	(7.9)
Other Comprehensive Income (Loss)	(5.3)	(0.5)
Unrealized Gains (Losses) on Cash Flow Hedges \| Foreign Exchange Contracts
AOCI Attributable To Parent, Before Tax [Abstract]
Gains (Losses)	6.3	9.8
AOCI Attributable To Parent, Tax [Abstract]
Gains (Losses)	(2.4)	(2.4)
AOCI Attributable To Parent, After Tax [Abstract]
Gains (Losses)	3.9	7.4
Foreign Currency Adjustments
AOCI Attributable To Parent, Before Tax [Abstract]
Net Change	22.3	(22.7)
AOCI Attributable To Parent, Tax [Abstract]
Net Change	(20.7)	27.4
AOCI Attributable To Parent, After Tax [Abstract]
Other Comprehensive Income (Loss)	1.6	4.7
Foreign Currency Translation Adjustments
AOCI Attributable To Parent, Before Tax [Abstract]
Net Change	(62.6)	91.4
AOCI Attributable To Parent, Tax [Abstract]
Net Change	0.0	(0.6)
AOCI Attributable To Parent, After Tax [Abstract]
Other Comprehensive Income (Loss)	(62.6)	90.8
Long-Term Intra-Entity Foreign Currency Transaction Gains (Losses)
AOCI Attributable To Parent, Before Tax [Abstract]
Net Change	0.4	0.2
AOCI Attributable To Parent, Tax [Abstract]
Net Change	0.0	0.0
AOCI Attributable To Parent, After Tax [Abstract]
Other Comprehensive Income (Loss)	0.4	0.2
Net Investment Hedge Gains (Losses)
AOCI Attributable To Parent, Before Tax [Abstract]
Net Change	84.5	(114.3)
AOCI Attributable To Parent, Tax [Abstract]
Net Change	(20.7)	28.0
AOCI Attributable To Parent, After Tax [Abstract]
Other Comprehensive Income (Loss)	63.8	(86.3)
Pension and Other Postretirement Benefit Adjustments
AOCI Attributable To Parent, Before Tax [Abstract]
Gains (Losses)	(5.5)	(3.4)
Net Change	1.4	(0.4)
AOCI Attributable To Parent, Tax [Abstract]
Gains (Losses)	2.5	0.4
Net Change	0.8	(0.3)
AOCI Attributable To Parent, After Tax [Abstract]
Gains (Losses)	(3.0)	(3.0)
Other Comprehensive Income (Loss)	2.2	(0.7)
Amortization of Net Actuarial Loss
AOCI Attributable To Parent, Before Tax [Abstract]
Reclassification Adjustments for (Gains) Losses Included in Net Income	6.4	3.0
AOCI Attributable To Parent, Tax [Abstract]
Reclassification Adjustments for (Gains) Losses Included in Net Income	(1.6)	(0.7)
AOCI Attributable To Parent, After Tax [Abstract]
Reclassification Adjustments for (Gains) Losses Included in Net Income	4.8	2.3
Amortization of Prior Service Cost (Credit)
AOCI Attributable To Parent, Before Tax [Abstract]
Reclassification Adjustments for (Gains) Losses Included in Net Income	0.5	0.0
AOCI Attributable To Parent, Tax [Abstract]
Reclassification Adjustments for (Gains) Losses Included in Net Income	(0.1)	0.0
AOCI Attributable To Parent, After Tax [Abstract]
Reclassification Adjustments for (Gains) Losses Included in Net Income	$ 0.4	$ 0.0

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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