Loans - Components of Loans (Details) - USD ($) $ in Millions		Mar. 31, 2024	Dec. 31, 2023
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net	[1]	$ 59,797	$ 58,987
Commercial loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net		40,305	39,957
Commercial loans | Real estate, including construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net		7,071	7,087
Commercial loans | Business and corporate banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net		16,047	15,724
Commercial loans | Global banking
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net		10,522	10,725
Commercial loans | Other commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net		6,665	6,421
Consumer loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net		19,492	19,030
Consumer loans | Residential mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net		18,825	18,341
Consumer loans | Home equity mortgages
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net		382	389
Consumer loans | Credit cards
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net		189	199
Consumer loans | Consumer Portfolio Segment [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net		96	101
Consumer loans | Student loans held for investment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, designated under fair value option		14	15
Affiliates | Commercial loans | Other commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net		3,442	2,618
Other | Commercial loans | Other commercial
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, net		$ 3,223	$ 3,803

[1] The following table summarizes assets and liabilities related to our consolidated variable interest entities ("VIEs") at March 31, 2024 and December 31, 2023. Assets and liabilities exclude intercompany balances that eliminate in consolidation. See Note 15, "Variable Interest Entities," for additional information. March 31, 2024December 31, 2023(in millions)AssetsOther assets$21 $23 Total assets$21 $23 LiabilitiesInterest, taxes and other liabilities$28 $17 Total liabilities$28 $17