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Net Investment Income (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024
Net Investment Income [Line Items] |  |  |  |
Gross investment income | $ 354,173 | $ 326,374 | $ 1,099,788 | $ 1,023,430
Investment expense | (2,935) | (2,618) | (8,955) | (7,707)
Net investment income | 351,238 | 323,756 | 1,090,833 | 1,015,723
Fixed maturity securities, including cash and cash equivalents and loans receivable |  |  |  |
Net Investment Income [Line Items] |  |  |  |
Gross investment income | 324,319 | 295,272 | 960,625 | 954,655
Arbitrage Trading Account |  |  |  |
Net Investment Income [Line Items] |  |  |  |
Gross investment income | 16,309 | 17,869 | 56,309 | 52,562
Equity securities |  |  |  |
Net Investment Income [Line Items] |  |  |  |
Gross investment income | 11,497 | 12,203 | 34,623 | 35,924
Investment funds |  |  |  |
Net Investment Income [Line Items] |  |  |  |
Gross investment income | 5,421 | 4,741 | 59,713 | 868
Real estate |  |  |  |
Net Investment Income [Line Items] |  |  |  |
Gross investment income | $ (3,373) | $ (3,711) | $ (11,482) | $ (20,579)

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