Loans - Wholesale Loan Portfolio, Loans Secured by Real Estate (Details) - USD ($) $ in Millions	Jun. 30, 2026	Dec. 31, 2025	Jun. 30, 2025
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 1,463,808	$ 1,408,905	$ 1,345,473
Wholesale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 846,804	$ 792,367	$ 740,675
% of criticized to total retained loans secured by real estate	3.46%	3.63%
% of criticized nonaccrual loans to total retained loans secured by real estate	0.49%	0.56%
Wholesale \| Criticized nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 4,191	$ 4,398
Wholesale \| Secured by real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 166,212	$ 165,545
% of criticized to total retained loans secured by real estate	6.22%	6.37%
% of criticized nonaccrual loans to total retained loans secured by real estate	0.92%	1.01%
Wholesale \| Secured by real estate \| Criticized
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 10,339	$ 10,550
% of criticized to total retained loans secured by real estate	6.22%	6.37%
Wholesale \| Secured by real estate \| Criticized nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 1,523	$ 1,678
% of criticized nonaccrual loans to total retained loans secured by real estate	0.92%	1.01%
Wholesale \| Secured by real estate \| Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 107,012	$ 105,130
Wholesale \| Secured by real estate \| Multifamily \| Criticized
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 4,963	$ 4,661
% of criticized to total retained loans secured by real estate	4.64%	4.43%
Wholesale \| Secured by real estate \| Multifamily \| Criticized nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 459	$ 422
% of criticized nonaccrual loans to total retained loans secured by real estate	0.43%	0.40%
Wholesale \| Secured by real estate \| Other commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 59,200	$ 60,415
Wholesale \| Secured by real estate \| Other commercial \| Criticized
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 5,376	$ 5,889
% of criticized to total retained loans secured by real estate	9.08%	9.75%
Wholesale \| Secured by real estate \| Other commercial \| Criticized nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 1,064	$ 1,256
% of criticized nonaccrual loans to total retained loans secured by real estate	1.80%	2.08%

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