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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 | 6 Months Ended
--- | --- | ---
Jun. 30, 2025 | Jun. 30, 2024 | Jun. 30, 2025 | Jun. 30, 2024
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |
Realized gains (losses) on securities | $ 2 | $ (2) | $ 5 | $ 12
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 | 2 | (2) | 10 | 11
Impairment allowance on securities | 0 | 0 | (6) | (2)
Realized gains (losses) on securities | 2 | (2) | 4 | 9
Change in unrealized | 40 | (12) | 101 | (3)
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 | 2 | (2) | 12 | 14
Impairment allowance on securities | 0 | 0 | (7) | (2)
Realized gains (losses) on securities | 2 | (2) | 5 | 12
Change in unrealized | 51 | (15) | 127 | (4)
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 | (8) | (1) | (7) | (5)
Impairment allowance on fixed maturity securities | 0 | 0 | (7) | (2)
Realized gains (losses) on securities | (8) | (1) | (14) | (7)
Change in unrealized | 51 | (15) | 127 | (4)
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 | 10 | (1) | 19 | 19
Realized gains (losses) on securities | 10 | (1) | 19 | 19
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 | 0 | 0 | (2) | (3)
Impairment allowance on securities | 0 | 0 | 1 | 0
Realized gains (losses) on securities | 0 | 0 | (1) | (3)
Change in unrealized | $ (11) | $ 3 | $ (26) | $ 1

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