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Investments in Marketable Securities - Additional Information (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2024 | Jun. 30, 2023 | Jun. 30, 2024 | Jun. 30, 2023 | Dec. 31, 2023
Marketable Securities [Line Items] |  |  |  |  |
Net unrealized gain (loss) | $ 0.2 | $ 2.6 | $ 1.6 | $ 3.9 |
Proceeds from maturity of AFS securities | 300.0 | 0.0 | 725.2 | 101.7 |
Debt securities, net unrealized gain (loss) | (0.2) | 0.0 | 0.6 | 0.0 |
Purchases of available-for-sale securities | 99.8 | $ 75.0 | 413.9 | $ 175.0 |
Variable Interest Entity, Primary Beneficiary |  |  |  |  |
Marketable Securities [Line Items] |  |  |  |  |
Fair value of deconsolidated investment in affiliate, equity securities | $ 12.1 |  | $ 12.1 |  | $ 15.8

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