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Investment Securities - Narrative (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Schedule of Held-to-maturity Securities [Line Items] |  |  |
Debt Securities, Available-for-sale, Realized Loss | $ (23.5) | $ (46.8) | $ (2.1)
Debt Securities, Available-for-sale, Realized Gain | 0.0 | $ 0.3 | $ 3.2
Debt Securities, Held-to-maturity, Nonaccrual | 0.0 |  |
Debt Securities, Current | 853.0 |  |
Investment Securities, Primarily Classified As Available-For-Sale, Debt Maturities, Rolling Year Two Through Five, Amortized Cost Basis | 1,603.3 |  |
Investment Securities, Primarily Classified As Available-For-Sale, Debt Maturities, Rolling Year Two Through Five, Fair Value | 1,552.2 |  |
Collateral |  |  |
Schedule of Held-to-maturity Securities [Line Items] |  |  |
Debt Securities | $ 0.0 |  |

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- Definition Investment Securities, Primarily Classified As Available-For-Sale, Callable, Within One Year, Amortized Cost Basis + References No definition available. + Details
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- Definition Investment Securities, Primarily Classified As Available-For-Sale, Callable, Within One Year, Fair Value + References No definition available. + Details
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- Definition Amount, after allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), investment in debt security measured at amortized cost (held-to-maturity), and investment in debt security measured at fair value with change in fair value recognized in net income (trading). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 944 -SubTopic 210 -Name Accounting Standards Codification -Section S99 -Paragraph 1 -Subparagraph (SX 210.7-03(a)(1)(a)) -Publisher FASB -URI https://asc.fasb.org//1943274/2147479440/944-210-S99-1 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Topic 320 -SubTopic 10 -Name Accounting Standards Codification -Section 45 -Paragraph 1 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147481830/320-10-45-1 + Details
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