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Investments - Schedule of sources of net investment income (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Net Investment Income [Line Items] |  |  |
Investment income | $ 802 | $ 758 | $ 733
Equity in earnings of partnerships and similar investments | 46 | 99 | 267
Investment expenses | (22) | (16) | (16)
Net investment income | 780 | 742 | 717
Net investment income |  |  |
Net Investment Income [Line Items] |  |  |
Change in fair value of equity securities | 57 | 36 | (2)
Fixed maturities | Net investment income |  |  |
Net Investment Income [Line Items] |  |  |
Change in fair value of fixed maturities | 17 | (3) | 0
Fixed maturities | Net investment income |  |  |
Net Investment Income [Line Items] |  |  |
Investment income | 544 | 502 | 376
Equity securities | Net investment income |  |  |
Net Investment Income [Line Items] |  |  |
Dividends | 29 | 34 | 39
Cash and cash equivalents |  |  |
Net Investment Income [Line Items] |  |  |
Investment income | 56 | 43 | 11
Other |  |  |
Net Investment Income [Line Items] |  |  |
Investment income | $ 53 | $ 47 | $ 42

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