Loans - Components of Loans (Details) - USD ($) $ in Millions	Mar. 31, 2026	Dec. 31, 2025
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net	$ 61,586	$ 59,894
Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net	41,234	39,344
Commercial loans | Commercial mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net	1,263	1,439
Commercial loans | Business and corporate banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net	30,635	28,305
Commercial loans | Other commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net	9,336	9,600
Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net	20,352	20,550
Consumer loans | Residential mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net	19,609	19,789
Consumer loans | Other consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net	743	761
Affiliates | Commercial loans | Other commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net	5,852	6,035
Other | Commercial loans | Other commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net	$ 3,484	$ 3,565