Expected Loss to be Paid (Recovered) - Key Assumptions in Base Case Expected Loss (Details) - RMBS - U.S.	Dec. 31, 2024	Dec. 31, 2023
Schedule of Expected Losses to be Paid [Line Items]
Loss severity		50.00%
Minimum
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	0.00%	0.00%
Final CDR	0.00%	0.00%
Liquidation rates	20.00%	20.00%
Loss severity	40.00%
Maximum
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	8.80%	10.00%
Final CDR	0.40%	0.50%
Liquidation rates	50.00%	65.00%
Loss severity	50.00%
Weighted Average
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	3.40%	4.20%
Final CDR	0.20%	0.20%
Loss severity	43.10%
Home equity lines of credit (HELOCs)
Schedule of Expected Losses to be Paid [Line Items]
Final CDR		0.00%
Loss severity	98.00%	98.00%
Projected future recoveries on previously charged-off loans	50.00%	40.00%
Home equity lines of credit (HELOCs) \| Minimum
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	0.00%	0.00%
Final CDR	0.00%
Liquidation rates	20.00%	20.00%
Home equity lines of credit (HELOCs) \| Maximum
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	5.60%	9.30%
Final CDR	0.30%	0.50%
Liquidation rates	55.00%	60.00%
Home equity lines of credit (HELOCs) \| Weighted Average
Schedule of Expected Losses to be Paid [Line Items]
Plateau CDR	2.20%	2.60%
Final CDR	0.10%	0.10%

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Loss Recovery Assumption of Charged-Off Loans, Estimated Future Recoveries, Percent

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