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Derivative Financial Instruments - Effect on Statement of Comprehensive Income and Statement of Income (Details) - Designated as Hedging Instrument - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2020 | Dec. 31, 2019
Derivatives in Net Investment Hedging Relationship |  |
Derivative [Line Items] |  |
Gain (Loss) Recorded in Other Comprehensive Income | $ 14.5 | $ (11.4)
Gain Reclassified from Accumulated Other Comprehensive Loss into Earnings | 0.6 | 0.5
Gain (Loss) Recorded in Earnings from Excluded Components | 2.8 | 13.9
Derivatives in Net Investment Hedging Relationship | Forward contracts |  |
Derivative [Line Items] |  |
Gain (Loss) Recorded in Other Comprehensive Income | 65.4 | (21.7)
Gain Reclassified from Accumulated Other Comprehensive Loss into Earnings | 0.6 | 0.5
Gain (Loss) Recorded in Earnings from Excluded Components | 2.8 | 13.9
Derivatives in Net Investment Hedging Relationship | Put options |  |
Derivative [Line Items] |  |
Gain (Loss) Recorded in Other Comprehensive Income | (47.7) | 29.3
Gain Reclassified from Accumulated Other Comprehensive Loss into Earnings | 0.0 | 0.0
Gain (Loss) Recorded in Earnings from Excluded Components | 0.0 | 0.0
Derivatives in Net Investment Hedging Relationship | Call options |  |
Derivative [Line Items] |  |
Gain (Loss) Recorded in Other Comprehensive Income | (1.3) | (19.0)
Gain Reclassified from Accumulated Other Comprehensive Loss into Earnings | 0.0 | 0.0
Gain (Loss) Recorded in Earnings from Excluded Components | 0.0 | 0.0
Cash Flow Hedging | Interest rate swap |  |
Derivative [Line Items] |  |
Gain (Loss) Recorded in Other Comprehensive Income | (1.9) | 0.0
Gain Reclassified from Accumulated Other Comprehensive Loss into Earnings | 0.0 | 0.0
Gain (Loss) Recorded in Earnings from Excluded Components | $ 0.0 | $ 0.0

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- Definition Gain (Loss) On Derivative Used In Cash Flow Hedge And Net Investment Hedge, After Tax + References No definition available. + Details
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- Definition Other Comprehensive Income (Loss), Cash Flow Hedge And Net Investment Hedge, Gain (Loss), After Reclassification And Tax, Parent + References No definition available. + Details
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- Definition Other Comprehensive Income (Loss), Net Investment Hedge, Gain (Loss), After Reclassification And Tax, Parent + References No definition available. + Details
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- Definition The net gain (loss) recognized in earnings during the reporting period representing the amount of the cash flow hedges' ineffectiveness. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624171-113959 + Details
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- Definition Amount, after tax and reclassification, of gain (loss) from derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness, attributable to parent. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e637-108580 + Details
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- Definition Amount, before tax and adjustments, of gain (loss) from increase (decrease) in value of excluded component of derivative designated and qualifying as hedge. Adjustments include, but are not limited to, reclassifications for sale and settlement, and amounts recognized under systematic and rational method. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 10A -Subparagraph (dd) -URI http://asc.fasb.org/extlink&oid=121641772&loc=SL7669646-108580 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (bb) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624171-113959 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=121641772&loc=d3e637-108580 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4CCC -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL109998896-113959 Reference 5: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 20 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=121577181&loc=SL110061190-113977 + Details
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