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Investment Information - Net investment Income (Details) - USD ($) $ in Millions | 12 Months Ended
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Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Net investment income: |  |  |  |
Gross investment income |  | $ 1,586 | $ 1,100 | $ 567
Investment expenses |  | (91) | (77) | (71)
Net investment income |  | 1,495 | 1,023 | 496
Fixed maturities |  |  |  |
Net investment income: |  |  |  |
Gross investment income |  | 1,266 | 917 | 469
Short-term investments |  |  |  |
Net investment income: |  |  |  |
Gross investment income |  | 144 | 68 | 29
Equity securities |  |  |  |
Net investment income: |  |  |  |
Gross investment income |  | 40 | 22 | 22
Other |  |  |  |
Net investment income: |  |  |  |
Gross investment income | [1] | $ 136 | $ 93 | $ 47
[1] | Amounts include dividends and other distributions on investment funds, term loan investments, funds held balances, cash balances and other items.

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