Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Narrative (Detail) - USD ($)		36 Months Ended
		Dec. 31, 2007	Mar. 31, 2024	Dec. 31, 2023
Guarantor Obligations [Line Items]
Deferred fees			$ 3,000,000	$ 3,000,000
Carrying value of swap			1,303,261,000,000	1,301,082,000,000
Estimate of reasonably possible loss			100,000,000
Fair Value	[1]		25,550,000,000	25,696,000,000
Trading assets	[1]		18,900,000,000	22,115,000,000
Collateral accepted under security resale agreements, fair value			12,474,000,000	19,278,000,000
Collateral accepted under security repurchase agreements but not reported on the balance sheet that can be sold or repledged, fair value			11,824,000,000	19,278,000,000
Collateral accepted under security repurchase agreements that has been sold or repledged under repurchase agreements or to cover short sales			1,288,000,000	2,696,000,000
Asset Pledged as Collateral with Right
Guarantor Obligations [Line Items]
Fair Value			863,000,000	161,000,000
Trading assets			2,472,000,000	3,046,000,000
Obligation to Repurchase Receivables Sold
Guarantor Obligations [Line Items]
Estimated repurchase liability			23,000,000	23,000,000
Obligation to Repurchase Receivables Sold | Minimum
Guarantor Obligations [Line Items]
Estimate of reasonably possible loss			0
Obligation to Repurchase Receivables Sold | Maximum
Guarantor Obligations [Line Items]
Estimate of reasonably possible loss			30,000,000
HSBC Securities
Guarantor Obligations [Line Items]
Whole loan securitization		$ 24,000,000,000
HSBC Securities | Mortgage Securitization Activity Related Litigation
Guarantor Obligations [Line Items]
Mortgage securitization outstanding loan purchase and sold			2,400,000,000	2,400,000,000
Other liabilities
Guarantor Obligations [Line Items]
Allowance for credit losses on unfunded standby letters of credit			20,000,000	17,000,000
Other liabilities | Standby Letters of Credit
Guarantor Obligations [Line Items]
Deferred fees			51,000,000	49,000,000
Swap
Guarantor Obligations [Line Items]
Carrying value of swap			$ 34,000,000	$ 40,000,000

[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