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Investments - Schedule of Investments in Two Sigma Funds (Details) - USD ($) $ in Thousands | Sep. 30, 2024 | Dec. 31, 2023
--- | --- | ---
Marketable Securities [Line Items] |  |
Cost | $ 829,606 | $ 770,191
Investments in Two Sigma Funds, at fair value | 932,787 | 851,470
Two Sigma Funds |  |
Marketable Securities [Line Items] |  |
Net Unrealized Gains (Losses) | 103,181 | 81,279
Investments in Two Sigma Funds, at fair value | 932,787 | 851,470
Two Sigma Futures Portfolio, LLC (FTV) |  |
Marketable Securities [Line Items] |  |
Cost | 352,138 | 433,911
Net Unrealized Gains (Losses) | 7,017 | (38,105)
Investments in Two Sigma Funds, at fair value | 359,155 | 395,806
Two Sigma Spectrum Portfolio, LLC (STV) |  |
Marketable Securities [Line Items] |  |
Cost | 337,247 | 193,299
Net Unrealized Gains (Losses) | 55,581 | 88,228
Investments in Two Sigma Funds, at fair value | 392,828 | 281,527
Two Sigma Equity Spectrum Portfolio, LLC (ESTV) |  |
Marketable Securities [Line Items] |  |
Cost | 140,221 | 142,981
Net Unrealized Gains (Losses) | 40,583 | 31,156
Investments in Two Sigma Funds, at fair value | $ 180,804 | $ 174,137

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