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Investments in Marketable Securities - Additional Information (Details) - USD ($) shares in Millions, $ in Millions | 1 Months Ended | 3 Months Ended | 6 Months Ended |
--- | --- | --- | --- | ---
Jul. 31, 2023 | Jun. 30, 2023 | Jun. 30, 2022 | Jun. 30, 2023 | Jun. 30, 2022 | Dec. 31, 2022
Marketable Securities [Line Items] |  |  |  |  |  |
Investments in equity securities, fair values |  | $ 95.8 |  | $ 95.8 |  | $ 447.9
Net unrealized gain (loss) |  | 2.6 | $ (18.7) | 3.9 | $ (24.9) |
Proceeds from maturity of AFS securities |  | 0.0 | 0.0 | 101.7 | 0.0 |
Debt securities, net unrealized gain (loss) |  | 0.0 | $ (1.9) | 0.0 | $ (2.7) |
EQT AB (“EQT”) |  |  |  |  |  |
Marketable Securities [Line Items] |  |  |  |  |  |
Investments in equity securities, fair values |  | 49.9 |  | 49.9 |  | 405.1
EQT AB (“EQT”) | Subsequent Event |  |  |  |  |  |
Marketable Securities [Line Items] |  |  |  |  |  |
Remaining shares sold | 2.6 |  |  |  |  |
Variable Interest Entity, Primary Beneficiary |  |  |  |  |  |
Marketable Securities [Line Items] |  |  |  |  |  |
Fair value of deconsolidated investment in affiliate, equity securities |  | $ 20.6 |  | $ 20.6 |  | $ 23.5

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