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Investments - Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |
Realized gains (losses) on securities | $ 12 | $ (2) | $ 17 | $ 10
Net of tax |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |
Realized gains (losses) on securities before impairments | 10 | 10 | 20 | 21
Impairment allowance on securities | 0 | (12) | (6) | (14)
Realized gains (losses) on securities | 10 | (2) | 14 | 7
Change in unrealized | 58 | 190 | 159 | 187
Total pretax |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |
Realized gains (losses) on securities before impairments | 13 | 13 | 25 | 27
Impairment allowance on securities | (1) | (15) | (8) | (17)
Realized gains (losses) on securities | 12 | (2) | 17 | 10
Change in unrealized | 74 | 241 | 201 | 237
Fixed maturities |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |
Realized gains (losses) on securities before impairments | 0 | 3 | (7) | (2)
Impairment allowance on fixed maturity securities | (1) | (15) | (8) | (17)
Realized gains (losses) on securities | (1) | (12) | (15) | (19)
Change in unrealized | 74 | 241 | 201 | 237
Equity securities |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |
Realized gains (losses) on securities before impairments | 13 | 10 | 32 | 29
Realized gains (losses) on securities | 13 | 10 | 32 | 29
Change in unrealized | 0 | 0 | 0 | 0
Mortgage loans and other investments |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |
Realized gains (losses) on securities before impairments | 0 | 0 | 0 | 0
Impairment allowance on mortgage loans and other investments | 0 | 0 | 0 | 0
Realized gains (losses) on securities | 0 | 0 | 0 | 0
Change in unrealized | 0 | 0 | 0 | 0
Total tax effects |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |
Realized gains (losses) on securities before impairments | (3) | (3) | (5) | (6)
Impairment allowance on securities | 1 | 3 | 2 | 3
Realized gains (losses) on securities | (2) | 0 | (3) | (3)
Change in unrealized | $ (16) | $ (51) | $ (42) | $ (50)

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