Loans - Wholesale Loan Portfolio, Loans Secured by Real Estate (Details) - USD ($) $ in Millions	Sep. 30, 2025	Dec. 31, 2024	Sep. 30, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 1,369,785	$ 1,299,590	$ 1,285,370
Wholesale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 764,451	$ 690,396	$ 687,890
% of criticized to total retained loans secured by real estate	3.46%	3.67%
% of criticized nonaccrual loans to total retained loans secured by real estate	0.62%	0.57%
Wholesale | Criticized nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 4,740	$ 3,942
Wholesale | Secured by real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 164,371	$ 162,432
% of criticized to total retained loans secured by real estate	6.37%	6.61%
% of criticized nonaccrual loans to total retained loans secured by real estate	0.93%	0.89%
Wholesale | Secured by real estate | Criticized
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 10,465	$ 10,730
% of criticized to total retained loans secured by real estate	6.37%	6.61%
Wholesale | Secured by real estate | Criticized nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 1,535	$ 1,439
% of criticized nonaccrual loans to total retained loans secured by real estate	0.93%	0.89%
Wholesale | Secured by real estate | Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 103,026	$ 101,114
Wholesale | Secured by real estate | Multifamily | Criticized
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 4,495	$ 4,700
% of criticized to total retained loans secured by real estate	4.36%	4.65%
Wholesale | Secured by real estate | Multifamily | Criticized nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 380	$ 337
% of criticized nonaccrual loans to total retained loans secured by real estate	0.37%	0.33%
Wholesale | Secured by real estate | Other commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 61,345	$ 61,318
Wholesale | Secured by real estate | Other commercial | Criticized
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 5,970	$ 6,030
% of criticized to total retained loans secured by real estate	9.73%	9.83%
Wholesale | Secured by real estate | Other commercial | Criticized nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 1,155	$ 1,102
% of criticized nonaccrual loans to total retained loans secured by real estate	1.88%	1.80%