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Investments (Net investment income) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Net Investment Income [Line Items] |  |  |
Gross investment income | $ 2,582 | $ 2,343 | $ 1,877
Investment expense | (85) | (79) | (72)
Net investment income | 2,497 | 2,264 | 1,805
Fixed maturity securities |  |  |
Net Investment Income [Line Items] |  |  |
Gross investment income | 2,051 | 1,941 | 1,787
Equity securities |  |  |
Net Investment Income [Line Items] |  |  |
Gross investment income | 82 | 63 | 23
Limited partnership investments |  |  |
Net Investment Income [Line Items] |  |  |
Gross investment income | 271 | 174 |
Gross investment loss |  |  | (12)
Mortgage loans |  |  |
Net Investment Income [Line Items] |  |  |
Gross investment income | 58 | 58 | 54
Short-term investments |  |  |
Net Investment Income [Line Items] |  |  |
Gross investment income | 87 | 75 | 16
Trading portfolio |  |  |
Net Investment Income [Line Items] |  |  |
Gross investment income | 2 | 4 | 4
Other |  |  |
Net Investment Income [Line Items] |  |  |
Gross investment income | 31 | 28 | 5
Common Stock |  |  |
Net Investment Income [Line Items] |  |  |
Equity securities, FV-NI, gain (loss) | 28 | 11 | 47
Non-redeemable preferred stock |  |  |
Net Investment Income [Line Items] |  |  |
Equity securities, FV-NI, gain (loss) | $ 19 | $ 14 | $ (75)

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