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Investments (Net investment income) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2022 | Dec. 31, 2021 | Dec. 31, 2020
Net Investment Income [Line Items] |  |  |
Gross investment income | $ 1,877 | $ 2,223 | $ 1,999
Investment expense | (72) | (64) | (64)
Net investment income | 1,805 | 2,159 | 1,935
Fixed maturity securities |  |  |
Net Investment Income [Line Items] |  |  |
Gross investment income | 1,787 | 1,707 | 1,728
Equity securities |  |  |
Net Investment Income [Line Items] |  |  |
Gross investment income | 23 | 83 | 65
Limited partnership investments |  |  |
Net Investment Income [Line Items] |  |  |
Gross investment income | (12) | 362 | 121
Mortgage loans |  |  |
Net Investment Income [Line Items] |  |  |
Gross investment income | 54 | 61 | 57
Short term investments |  |  |
Net Investment Income [Line Items] |  |  |
Gross investment income | 16 | 1 | 9
Trading portfolio |  |  |
Net Investment Income [Line Items] |  |  |
Gross investment income | 4 | 9 | 18
Other |  |  |
Net Investment Income [Line Items] |  |  |
Gross investment income | 5 | 0 | 1
Common Stock |  |  |
Net Investment Income [Line Items] |  |  |
Equity securities, FV-NI, gain (loss) | 47 | 28 | 34
Non-redeemable preferred stock |  |  |
Net Investment Income [Line Items] |  |  |
Equity securities, FV-NI, gain (loss) | $ (75) | $ 2 | $ (3)

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