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Investments - Schedule of sources of net investment income (Details) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2024 | Mar. 31, 2023
Net Investment Income [Line Items] |  |
Investment income | $ 204 | $ 222
Equity in earnings of partnerships and similar investments | 25 | 57
Investment expenses | (6) | (5)
Net investment income | 198 | 217
Fixed maturities: | Net investment income |  |
Net Investment Income [Line Items] |  |
Investment income | 134 | 119
Fixed maturities: | Net investment income |  |
Net Investment Income [Line Items] |  |
Change in fair value | 0 | 3
Equity securities | Net investment income |  |
Net Investment Income [Line Items] |  |
Change in fair value of equity securities | 16 | 16
Other |  |
Net Investment Income [Line Items] |  |
Investment income | 22 | 18
Net investment income | Equity securities |  |
Net Investment Income [Line Items] |  |
Investment income | $ 7 | $ 9

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