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Investments in Marketable Securities - Additional Information (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2024 | Sep. 30, 2023 | Sep. 30, 2024 | Sep. 30, 2023 | Dec. 31, 2023
Marketable Securities [Line Items] |  |  |  |  |
Net unrealized gain (loss) | $ 2.0 | $ (2.1) | $ 3.5 | $ 1.3 |
Proceeds from maturity of AFS securities | 100.0 | 178.4 | 825.2 | 280.1 |
Purchase of available-for-sale securities | 0.0 | 245.3 | 413.9 | 420.3 |
Debt securities, net unrealized gain | 0.8 | $ 0.0 | 1.4 | $ 0.0 |
Variable Interest Entity, Primary Beneficiary |  |  |  |  |
Marketable Securities [Line Items] |  |  |  |  |
Fair value of deconsolidated investment in affiliate, equity securities | $ 11.9 |  | $ 11.9 |  | $ 15.8

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