Fair Value Measurements - Carrying Value and Estimated Fair Value of Financial Instruments (Detail) - USD ($) $ in Millions		Sep. 30, 2022		Dec. 31, 2021		Sep. 30, 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]	$ 29,825		$ 10,514
Total loans, net		61,224	[1]	55,417	[1]	$ 55,051
Loans held for sale	[1]	576		4,217
Deposits		124,966	[1]	143,032	[1]	$ 152,368
Long-term debt	[1]	15,696		17,236
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		944		954
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
Deposits held for sale				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		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		13,970		47,400
Federal funds sold and securities purchased under agreements to resell		29,825		10,514
Securities held-to-maturity, net of allowance for credit losses		6,181		5,359
Short-term financial liabilities		6,536		6,338
Deposits		123,180		131,533
Deposits held for sale				8,750
Long-term debt		9,259		8,861
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		329		359
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		7		77
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		52		50
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		53		51
Deposits		0		0
Deposits held for sale				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		43,835		39,862
Loans held for sale		0		84
Level 3 | Consumer loans
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Total loans, net		15,815		15,672
Loans held for sale		74		3,732
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		14,966		48,404
Federal funds sold and securities purchased under agreements to resell		29,825		10,514
Securities held-to-maturity, net of allowance for credit losses		6,656		5,203
Short-term financial liabilities		6,589		6,389
Deposits		123,204		131,533
Deposits held for sale				8,750
Long-term debt		8,695		8,294
Carrying Value | Commercial loans
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Total loans, net		43,951		39,376
Loans held for sale		329		438
Carrying Value | Consumer loans
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Total loans, net		17,273		16,041
Loans held for sale		81		3,731
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		14,966		48,404
Federal funds sold and securities purchased under agreements to resell		29,825		10,514
Securities held-to-maturity, net of allowance for credit losses		6,181		5,359
Short-term financial liabilities		6,589		6,389
Deposits		123,180		131,533
Deposits held for sale				8,750
Long-term debt		9,259		8,861
Fair Value | Commercial loans
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Total loans, net		43,835		39,862
Loans held for sale		329		443
Fair Value | Consumer loans
Fair Value Disclosure, Asset and Liability, Not Measured at Fair Value [Line Items]
Total loans, net		15,815		15,672
Loans held for sale		$ 81		$ 3,809

[1] The following table summarizes assets and liabilities related to our consolidated variable interest entities ("VIEs") at September 30, 2022 and December 31, 2021. Assets and liabilities exclude intercompany balances that eliminate in consolidation. See Note 17, "Variable Interest Entities," for additional information. September 30, 2022December 31, 2021(in millions)AssetsLoans$127 $46 Other assets44 55 Total assets$171 $101 LiabilitiesInterest, taxes and other liabilities$26 $9 Total liabilities$26 $9