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Net Investment Income (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2022 | Sep. 30, 2021 | Sep. 30, 2022 | Sep. 30, 2021
Net Investment Income [Line Items] |  |  |  |
Gross investment income | $ 205,143 | $ 181,457 | $ 554,252 | $ 511,789
Investment expense | (2,327) | (1,606) | (6,350) | (5,174)
Net investment income | 202,816 | 179,851 | 547,902 | 506,615
Fixed maturity securities, including cash and cash equivalents and loans receivable |  |  |  |
Net Investment Income [Line Items] |  |  |  |
Gross investment income | 146,051 | 93,031 | 371,724 | 284,704
Investment funds |  |  |  |
Net Investment Income [Line Items] |  |  |  |
Investment funds | 36,045 | 69,292 | 121,919 | 169,538
Arbitrage trading account |  |  |  |
Net Investment Income [Line Items] |  |  |  |
Gross investment income | 10,694 | 7,187 | 24,008 | 30,176
Equity securities |  |  |  |
Net Investment Income [Line Items] |  |  |  |
Gross investment income | 14,650 | 8,462 | 38,303 | 21,854
Real estate |  |  |  |
Net Investment Income [Line Items] |  |  |  |
Gross investment income | $ (2,297) | $ 3,485 | $ (1,702) | $ 5,517

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