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Expected Loss to be Paid (Recovered) - Net Economic Loss Development (Benefit) (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2023 | Sep. 30, 2022 | Sep. 30, 2023 | Sep. 30, 2022
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |
RMBS losses | $ 87 | $ (72) | $ 147 | $ (148)
RMBS | United States |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |
RMBS losses | (48) | (95) | (52) | (127)
RMBS | United States | First Lien |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |
RMBS losses | (12) | (38) | (12) | (34)
RMBS | United States | Second Lien |  |  |  |
Schedule of Expected Losses to be Paid [Line Items] |  |  |  |
RMBS losses | $ (36) | $ (57) | $ (40) | $ (93)

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