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Expected Loss to be Paid (Recovered) - Net Economic Loss Development (Benefit) (Details) - USD ($) $ in Millions | 3 Months Ended
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Mar. 31, 2025 | Mar. 31, 2024
Schedule of Expected Losses to be Paid [Line Items] |  |
RMBS losses | $ (15) | $ (7)
RMBS | United States |  |
Schedule of Expected Losses to be Paid [Line Items] |  |
RMBS losses | (3) | (3)
RMBS | United States | First Lien |  |
Schedule of Expected Losses to be Paid [Line Items] |  |
RMBS losses | 2 | (1)
RMBS | United States | Second Lien |  |
Schedule of Expected Losses to be Paid [Line Items] |  |
RMBS losses | $ (5) | $ (2)

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