Loans - Wholesale Loan Portfolio, Loans Secured by Real Estate (Details) - USD ($) $ in Millions	Sep. 30, 2026	Dec. 31, 2025	Sep. 30, 2025
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 1,497,159	$ 1,408,905	$ 1,369,785
Wholesale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 877,256	$ 792,367	$ 764,451
% of criticized to total retained loans secured by real estate	3.37%	3.63%
% of criticized nonaccrual loans to total retained loans secured by real estate	0.48%	0.56%
Wholesale \| Criticized nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 4,202	$ 4,398
Wholesale \| Secured by real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 167,699	$ 165,545
% of criticized to total retained loans secured by real estate	6.37%	6.37%
% of criticized nonaccrual loans to total retained loans secured by real estate	0.93%	1.01%
Wholesale \| Secured by real estate \| Criticized
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 10,676	$ 10,550
% of criticized to total retained loans secured by real estate	6.37%	6.37%
Wholesale \| Secured by real estate \| Criticized nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 1,554	$ 1,678
% of criticized nonaccrual loans to total retained loans secured by real estate	0.93%	1.01%
Wholesale \| Secured by real estate \| Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 108,307	$ 105,130
Wholesale \| Secured by real estate \| Multifamily \| Criticized
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 5,325	$ 4,661
% of criticized to total retained loans secured by real estate	4.92%	4.43%
Wholesale \| Secured by real estate \| Multifamily \| Criticized nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 553	$ 422
% of criticized nonaccrual loans to total retained loans secured by real estate	0.51%	0.40%
Wholesale \| Secured by real estate \| Other commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 59,392	$ 60,415
Wholesale \| Secured by real estate \| Other commercial \| Criticized
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 5,351	$ 5,889
% of criticized to total retained loans secured by real estate	9.01%	9.75%
Wholesale \| Secured by real estate \| Other commercial \| Criticized nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 1,001	$ 1,256
% of criticized nonaccrual loans to total retained loans secured by real estate	1.69%	2.08%

Accounts, Notes, Loans and Financing Receivable [Line Items]