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Investments - Schedule of sources of net investment income (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2023 | Jun. 30, 2022 | Jun. 30, 2023 | Jun. 30, 2022
Net Investment Income [Line Items] |  |  |  |
Investment income | $ 203 | $ 173 | $ 425 | $ 407
Equity in earnings of partnerships and similar investments | 28 | 76 | 85 | 209
Investment expenses | (5) | (5) | (10) | (9)
Net investment income | 198 | 168 | 415 | 398
Fixed maturities: | Net investment income |  |  |  |
Net Investment Income [Line Items] |  |  |  |
Investment income | 124 | 85 | 243 | 165
Fixed maturities: | Net investment income |  |  |  |
Net Investment Income [Line Items] |  |  |  |
Investment income | 7 | 0 | 10 | 0
Equity securities | Net investment income |  |  |  |
Net Investment Income [Line Items] |  |  |  |
Change in fair value of equity securities | 13 | (9) | 29 | (2)
Other |  |  |  |
Net Investment Income [Line Items] |  |  |  |
Investment income | 22 | 13 | 40 | 20
Net investment income | Equity securities |  |  |  |
Net Investment Income [Line Items] |  |  |  |
Investment income | $ 9 | $ 8 | $ 18 | $ 15

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