Expected Loss to be Paid (Recovered) - Key Assumptions in Base Case Expected Loss First Lien RMBS (Details) - U.S. - RMBS	Dec. 31, 2023	Dec. 31, 2022
Alt-A
Schedule of Expected Losses to be Paid [Line Items]
Initial loss severity	50.00%	50.00%
Alt-A | Minimum
Schedule of Expected Losses to be Paid [Line Items]
CDR plateau	1.40%	1.60%
Final CDR	0.10%	0.10%
Alt-A | Maximum
Schedule of Expected Losses to be Paid [Line Items]
CDR plateau	9.00%	11.50%
Final CDR	0.40%	0.60%
Alt-A | Weighted Average
Schedule of Expected Losses to be Paid [Line Items]
CDR plateau	3.60%	5.10%
Final CDR	0.20%	0.30%
Adjustable Rate Residential Mortgage [Member]
Schedule of Expected Losses to be Paid [Line Items]
Initial loss severity	50.00%	50.00%
Adjustable Rate Residential Mortgage [Member] | Minimum
Schedule of Expected Losses to be Paid [Line Items]
CDR plateau	0.00%	2.00%
Final CDR	0.00%	0.10%
Adjustable Rate Residential Mortgage [Member] | Maximum
Schedule of Expected Losses to be Paid [Line Items]
CDR plateau	8.90%	7.70%
Final CDR	0.40%	0.40%
Adjustable Rate Residential Mortgage [Member] | Weighted Average
Schedule of Expected Losses to be Paid [Line Items]
CDR plateau	3.30%	4.30%
Final CDR	0.20%	0.20%
Financing Receivable, Subprime [Member]
Schedule of Expected Losses to be Paid [Line Items]
Initial loss severity	50.00%	50.00%
Financing Receivable, Subprime [Member] | Minimum
Schedule of Expected Losses to be Paid [Line Items]
CDR plateau	0.30%	2.70%
Final CDR	0.00%	0.10%
Financing Receivable, Subprime [Member] | Maximum
Schedule of Expected Losses to be Paid [Line Items]
CDR plateau	10.00%	9.70%
Final CDR	0.50%	0.50%
Financing Receivable, Subprime [Member] | Weighted Average
Schedule of Expected Losses to be Paid [Line Items]
CDR plateau	4.40%	5.60%
Final CDR	0.20%	0.30%