Loans - Wholesale Loan Portfolio, Loans Secured by Real Estate (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025	Mar. 31, 2025
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 1,425,236	$ 1,408,905	$ 1,300,990
Wholesale
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 818,839	$ 792,367	$ 704,714
% of criticized to total retained loans secured by real estate	3.65%	3.63%
% of criticized nonaccrual loans to total retained loans secured by real estate	0.55%	0.56%
Wholesale | Criticized nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 4,524	$ 4,398
Wholesale | Secured by real estate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 166,189	$ 165,545
% of criticized to total retained loans secured by real estate	6.33%	6.37%
% of criticized nonaccrual loans to total retained loans secured by real estate	1.05%	1.01%
Wholesale | Secured by real estate | Criticized
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 10,521	$ 10,550
% of criticized to total retained loans secured by real estate	6.33%	6.37%
Wholesale | Secured by real estate | Criticized nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 1,743	$ 1,678
% of criticized nonaccrual loans to total retained loans secured by real estate	1.05%	1.01%
Wholesale | Secured by real estate | Multifamily
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 105,899	$ 105,130
Wholesale | Secured by real estate | Multifamily | Criticized
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 4,866	$ 4,661
% of criticized to total retained loans secured by real estate	4.59%	4.43%
Wholesale | Secured by real estate | Multifamily | Criticized nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 428	$ 422
% of criticized nonaccrual loans to total retained loans secured by real estate	0.40%	0.40%
Wholesale | Secured by real estate | Other commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 60,290	$ 60,415
Wholesale | Secured by real estate | Other commercial | Criticized
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 5,655	$ 5,889
% of criticized to total retained loans secured by real estate	9.38%	9.75%
Wholesale | Secured by real estate | Other commercial | Criticized nonaccrual
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total retained loans	$ 1,315	$ 1,256
% of criticized nonaccrual loans to total retained loans secured by real estate	2.18%	2.08%