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Investment Funds (Details) - USD ($) $ in Thousands |  | 3 Months Ended | 9 Months Ended | 18 Months Ended |
--- | --- | --- | --- | --- | ---
Jul. 01, 2022 | Sep. 30, 2023 | Sep. 30, 2022 | Sep. 30, 2023 | Sep. 30, 2022 | Jun. 30, 2022 | Dec. 31, 2022
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Unfunded commitments |  | $ 353,000 |  | $ 353,000 |  |  |
Investment funds |  | 1,600,495 |  | 1,600,495 |  |  | $ 1,608,548
Income (Loss) from Investment Funds |  |  |  | 5,444 | $ 121,919 |  |
Written premiums ceded |  | 504,746 | $ 504,664 | 1,504,497 | 1,418,012 |  |
Fair Value |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Trading account receivables from brokers and clearing organizations |  | 401,982 |  | 401,982 |  |  | 233,863
Lifson Re |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Percentage of reinsurance placements of share placed amounts | 30.00% |  |  |  |  | 22.50% |
Written premiums ceded |  |  |  | 348,000 | 308,000 |  |
Financial services |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Investment funds |  | 191,445 |  | 191,445 |  |  | 204,644
Income (Loss) from Investment Funds |  |  |  | (5,062) | 42,708 |  |
Transportation |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Investment funds |  | 429,889 |  | 429,889 |  |  | 465,683
Income (Loss) from Investment Funds |  |  |  | (15,606) | 27,472 |  |
Real Estate |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Investment funds |  | 336,020 |  | 336,020 |  |  | 336,753
Income (Loss) from Investment Funds |  |  |  | 37,894 | 48,249 |  |
Energy |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Investment funds |  | 115,349 |  | 115,349 |  |  | 116,432
Income (Loss) from Investment Funds |  |  |  | 3,921 | 1,966 |  |
Infrastructure |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Investment funds |  | 124,528 |  | 124,528 |  |  | 115,428
Income (Loss) from Investment Funds |  |  |  | 7,813 | 1,277 |  |
Other funds |  |  |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |  |  |
Investment funds |  | 403,264 |  | 403,264 |  |  | 369,608
Income (Loss) from Investment Funds |  |  |  | (23,516) | $ 247 |  |
Deferred compensation trust assets |  | $ 31,000 |  | $ 31,000 |  |  | $ 30,000

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