Fair Value Measurements - Carrying Value and Estimated Fair Value of Financial Instruments (Detail) - USD ($) $ in Millions		Dec. 31, 2023		Dec. 31, 2022		Dec. 31, 2021
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Federal funds sold and securities purchased under agreements to resell	[1]	$ 13,878		$ 23,085
Total loans, net		58,396	[1]	58,796	[1]	$ 55,417
Loans held for sale	[1]	339		354
Deposits		121,283	[1]	123,223	[1]	$ 143,032
Long-term debt	[1]	18,661		17,591
Level 1
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Short-term financial assets, net of allowance for credit losses		704		1,004
Federal funds sold and securities purchased under agreements to resell		0		0
Securities held-to-maturity, net of allowance for credit losses		0		0
Short-term financial liabilities		0		0
Deposits		0		0
Long-term debt		0		0
Level 1 | Commercial loans
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Total loans, net		0		0
Loans held for sale		0		0
Level 1 | Consumer loans
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Total loans, net		0		0
Loans held for sale				0
Level 2
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Short-term financial assets, net of allowance for credit losses		25,015		17,744
Federal funds sold and securities purchased under agreements to resell		13,878		23,085
Securities held-to-maturity, net of allowance for credit losses		14,689		6,862
Short-term financial liabilities		9,914		5,945
Deposits		119,465		121,652
Long-term debt		11,645		9,769
Level 2 | Commercial loans
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Total loans, net		0		0
Loans held for sale		89		112
Level 2 | Consumer loans
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Total loans, net		0		0
Loans held for sale				5
Level 3
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Short-term financial assets, net of allowance for credit losses		13		54
Federal funds sold and securities purchased under agreements to resell		0		0
Securities held-to-maturity, net of allowance for credit losses		0		0
Short-term financial liabilities		13		54
Deposits		0		0
Long-term debt		0		0
Level 3 | Commercial loans
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Total loans, net		40,557		42,050
Loans held for sale		0		0
Level 3 | Consumer loans
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Total loans, net		17,043		15,984
Loans held for sale				0
Carrying Value
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Short-term financial assets, net of allowance for credit losses		25,732		18,802
Federal funds sold and securities purchased under agreements to resell		13,878		23,085
Securities held-to-maturity, net of allowance for credit losses		15,076		7,317
Short-term financial liabilities		9,927		5,999
Deposits		119,462		121,669
Long-term debt		11,122		9,213
Carrying Value | Commercial loans
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Total loans, net		39,383		41,266
Loans held for sale		89		112
Carrying Value | Consumer loans
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Total loans, net		18,998		17,510
Loans held for sale				5
Fair Value
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Short-term financial assets, net of allowance for credit losses		25,732		18,802
Federal funds sold and securities purchased under agreements to resell		13,878		23,085
Securities held-to-maturity, net of allowance for credit losses		14,689		6,862
Short-term financial liabilities		9,927		5,999
Deposits		119,465		121,652
Long-term debt		11,645		9,769
Fair Value | Commercial loans
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Total loans, net		40,557		42,050
Loans held for sale		89		112
Fair Value | Consumer loans
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Total loans, net		$ 17,043		15,984
Loans held for sale				$ 5

[1] The following table summarizes assets and liabilities related to our consolidated variable interest entities ("VIEs") at December 31, 2023 and 2022. Assets and liabilities exclude intercompany balances that eliminate in consolidation. See Note 27, "Variable Interest Entities," for additional information. At December 31,20232022(in millions)AssetsLoans, net$— $162 Other assets23 44 Total assets$23 $206 LiabilitiesInterest, taxes and other liabilities$17 $22 Total liabilities$17 $22