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Investments (Net Realized Gains (Losses) And Losses Included In Net Realized Gains (Losses) And Other Comprehensive Income) (Detail) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024
Gain (Loss) on Securities [Line Items] |  |  |  |  |
Net realized gains (losses) |  | $ 283 | $ 198 | $ 327 | $ 201
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Period Increase (Decrease) |  | 25 | 23 | 76 | 95
Debt Securities, Available-for-sale, Gain (Loss), Total |  | 46 | 111 | (58) | 186
Foreign exchange |  | (115) | (58) | (269) | (162)
Other |  | 2 | (1) | (5) | (8)
Fixed Maturities [Member] |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |
Debt Securities, Available-for-Sale, Realized Gain |  | 121 | 21 | 228 | 73
Debt Securities, Available-for-Sale, Realized Loss |  | 157 | 91 | 376 | 338
Debt Securities, Available-for-Sale, Allowance for Credit Loss, Period Increase (Decrease) |  | 22 | 48 | 21 | 80
Debt Securities, Available-For-Sale, Credit Impairment Charges Intent to Sell | [1] | (22) | (19) | (34) | (81)
Other Investments |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |
Net realized gains (losses) |  | 82 | 152 | 103 | 452
Equity Securities |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |
Equity Securities, FV-NI, Realized Gain (Loss) |  | 396 | 123 | 596 | 147
Private equities |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |
Net realized gains (losses) |  | 48 | (41) | 31 | 39
Other investments - Fixed Maturities [Member] |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |
Net realized gains (losses) |  | (116) |  | (116) |
Reserved alternative investment fund |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |
Equity Securities, FV-NI, Realized Gain (Loss) |  | 66 |  | 131 |
Investment and embedded derivative instruments |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |
Gain (Loss) on Derivative |  | (85) | 66 | 46 | 6
Other derivative instruments |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |
Gain (Loss) on Derivative |  | $ (9) | $ (2) | $ (14) | $ (7)
[1] | Relates to certain securities we intend to sell and securities written to market entering default.

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