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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, 2024 | Jun. 30, 2023 | Jun. 30, 2024 | Jun. 30, 2023
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |
Realized gains (losses) on securities | $ (2) | $ (2) | $ 12 | $ (48)
Net of tax |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |
Realized gains (losses) securities before impairments | (2) | (1) | 11 | (34)
Impairment allowance on securities | 0 | 0 | (2) | (4)
Realized gains (losses) on securities | (2) | (1) | 9 | (38)
Change in unrealized | (12) | (51) | (3) | 33
Total pretax |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |
Realized gains (losses) securities before impairments | (2) | (2) | 14 | (43)
Impairment allowance on securities | 0 | 0 | (2) | (5)
Realized gains (losses) on securities | (2) | (2) | 12 | (48)
Change in unrealized | (15) | (64) | (4) | 43
Fixed maturities: |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |
Realized gains (losses) securities before impairments | (1) | (5) | (5) | (28)
Impairment allowance on fixed maturity securities | 0 | 0 | (2) | (5)
Realized gains (losses) on securities | (1) | (5) | (7) | (33)
Change in unrealized | (15) | (64) | (4) | 43
Equity securities |  |  |  |
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments |  |  |  |
Realized gains (losses) securities before impairments | (1) | 3 | 19 | (15)
Realized gains (losses) on securities | (1) | 3 | 19 | (15)
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) 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) securities before impairments | 0 | 1 | (3) | 9
Impairment allowance on securities | 0 | 0 | 0 | 1
Realized gains (losses) on securities | 0 | 1 | (3) | 10
Change in unrealized | $ 3 | $ 13 | $ 1 | $ (10)

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