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Expected Loss to be Paid (Recovered) - Net Expected Loss to be Paid (Recovered) and Net Economic Loss Development (Benefit) by Accounting Model (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Sep. 30, 2025 | Sep. 30, 2024 | Sep. 30, 2025 | Sep. 30, 2024 | Jun. 30, 2025 | Dec. 31, 2024 | Jun. 30, 2024 | Dec. 31, 2023
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Net Expected Loss to be Paid (Recovered) | $ 104 | $ 306 | $ 104 | $ 306 | $ 186 | $ 106 | $ 447 | $ 505
Net economic loss development (benefit) | (38) | (34) | (17) | (20) |  |  |  |
Insurance |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Net Expected Loss to be Paid (Recovered) | 92 |  | 92 |  |  | 90 |  |
Net economic loss development (benefit) | (35) | (31) | 51 | (19) |  |  |  |
FG VIEs' assets |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Net Expected Loss to be Paid (Recovered) | 12 |  | 12 |  |  | 16 |  |
Net economic loss development (benefit) | (4) | (1) | (5) | 0 |  |  |  |
Credit derivatives |  |  |  |  |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |  |  |  |  |
Net Expected Loss to be Paid (Recovered) | 0 |  | 0 |  |  | $ 0 |  |
Net economic loss development (benefit) | $ 1 | $ (2) | $ (63) | $ (1) |  |  |  |

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