Loans - Financing Receivable, Modified - Modification to Borrowers Experiencing Financial Difficulty (Details) $ in Millions	Mar. 31, 2023 USD ($)
Financing Receivable, Past Due [Line Items]
Total Loans	$ 787
FDM commitment to lend	26
Current
Financing Receivable, Past Due [Line Items]
Total Loans	527
30-59 days
Financing Receivable, Past Due [Line Items]
Total Loans	89
60-89 days
Financing Receivable, Past Due [Line Items]
Total Loans	34
Greater than 90 days
Financing Receivable, Past Due [Line Items]
Total Loans	137
Total Delinquent Loans
Financing Receivable, Past Due [Line Items]
Total Loans	260
Credit Card
Financing Receivable, Past Due [Line Items]
Total Loans	188
Credit Card | Current
Financing Receivable, Past Due [Line Items]
Total Loans	73
Credit Card | 30-59 days
Financing Receivable, Past Due [Line Items]
Total Loans	41
Credit Card | 60-89 days
Financing Receivable, Past Due [Line Items]
Total Loans	27
Credit Card | Greater than 90 days
Financing Receivable, Past Due [Line Items]
Total Loans	47
Credit Card | Total Delinquent Loans
Financing Receivable, Past Due [Line Items]
Total Loans	115
Credit Card | Domestic Card
Financing Receivable, Past Due [Line Items]
Total Loans	150
Credit Card | Domestic Card | Current
Financing Receivable, Past Due [Line Items]
Total Loans	62
Credit Card | Domestic Card | 30-59 days
Financing Receivable, Past Due [Line Items]
Total Loans	36
Credit Card | Domestic Card | 60-89 days
Financing Receivable, Past Due [Line Items]
Total Loans	23
Credit Card | Domestic Card | Greater than 90 days
Financing Receivable, Past Due [Line Items]
Total Loans	29
Credit Card | Domestic Card | Total Delinquent Loans
Financing Receivable, Past Due [Line Items]
Total Loans	88
Credit Card | International card businesses
Financing Receivable, Past Due [Line Items]
Total Loans	38
Credit Card | International card businesses | Current
Financing Receivable, Past Due [Line Items]
Total Loans	11
Credit Card | International card businesses | 30-59 days
Financing Receivable, Past Due [Line Items]
Total Loans	5
Credit Card | International card businesses | 60-89 days
Financing Receivable, Past Due [Line Items]
Total Loans	4
Credit Card | International card businesses | Greater than 90 days
Financing Receivable, Past Due [Line Items]
Total Loans	18
Credit Card | International card businesses | Total Delinquent Loans
Financing Receivable, Past Due [Line Items]
Total Loans	27
Consumer Banking
Financing Receivable, Past Due [Line Items]
Total Loans	255
Consumer Banking | Current
Financing Receivable, Past Due [Line Items]
Total Loans	226
Consumer Banking | 30-59 days
Financing Receivable, Past Due [Line Items]
Total Loans	18
Consumer Banking | 60-89 days
Financing Receivable, Past Due [Line Items]
Total Loans	7
Consumer Banking | Greater than 90 days
Financing Receivable, Past Due [Line Items]
Total Loans	4
Consumer Banking | Total Delinquent Loans
Financing Receivable, Past Due [Line Items]
Total Loans	29
Consumer Banking | Auto
Financing Receivable, Past Due [Line Items]
Total Loans	252
Consumer Banking | Auto | Current
Financing Receivable, Past Due [Line Items]
Total Loans	224
Consumer Banking | Auto | 30-59 days
Financing Receivable, Past Due [Line Items]
Total Loans	18
Consumer Banking | Auto | 60-89 days
Financing Receivable, Past Due [Line Items]
Total Loans	7
Consumer Banking | Auto | Greater than 90 days
Financing Receivable, Past Due [Line Items]
Total Loans	3
Consumer Banking | Auto | Total Delinquent Loans
Financing Receivable, Past Due [Line Items]
Total Loans	28
Consumer Banking | Retail banking
Financing Receivable, Past Due [Line Items]
Total Loans	3
Consumer Banking | Retail banking | Current
Financing Receivable, Past Due [Line Items]
Total Loans	2
Consumer Banking | Retail banking | 30-59 days
Financing Receivable, Past Due [Line Items]
Total Loans	0
Consumer Banking | Retail banking | 60-89 days
Financing Receivable, Past Due [Line Items]
Total Loans	0
Consumer Banking | Retail banking | Greater than 90 days
Financing Receivable, Past Due [Line Items]
Total Loans	1
Consumer Banking | Retail banking | Total Delinquent Loans
Financing Receivable, Past Due [Line Items]
Total Loans	1
Commercial Banking
Financing Receivable, Past Due [Line Items]
Total Loans	344
Commercial Banking | Current
Financing Receivable, Past Due [Line Items]
Total Loans	228
Commercial Banking | 30-59 days
Financing Receivable, Past Due [Line Items]
Total Loans	30
Commercial Banking | 60-89 days
Financing Receivable, Past Due [Line Items]
Total Loans	0
Commercial Banking | Greater than 90 days
Financing Receivable, Past Due [Line Items]
Total Loans	86
Commercial Banking | Total Delinquent Loans
Financing Receivable, Past Due [Line Items]
Total Loans	116
Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Past Due [Line Items]
Total Loans	129
Commercial Banking | Commercial and multifamily real estate | Current
Financing Receivable, Past Due [Line Items]
Total Loans	99
Commercial Banking | Commercial and multifamily real estate | 30-59 days
Financing Receivable, Past Due [Line Items]
Total Loans	30
Commercial Banking | Commercial and multifamily real estate | 60-89 days
Financing Receivable, Past Due [Line Items]
Total Loans	0
Commercial Banking | Commercial and multifamily real estate | Greater than 90 days
Financing Receivable, Past Due [Line Items]
Total Loans	0
Commercial Banking | Commercial and multifamily real estate | Total Delinquent Loans
Financing Receivable, Past Due [Line Items]
Total Loans	30
Commercial Banking | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Total Loans	215
Commercial Banking | Commercial and industrial | Current
Financing Receivable, Past Due [Line Items]
Total Loans	129
Commercial Banking | Commercial and industrial | 30-59 days
Financing Receivable, Past Due [Line Items]
Total Loans	0
Commercial Banking | Commercial and industrial | 60-89 days
Financing Receivable, Past Due [Line Items]
Total Loans	0
Commercial Banking | Commercial and industrial | Greater than 90 days
Financing Receivable, Past Due [Line Items]
Total Loans	86
Commercial Banking | Commercial and industrial | Total Delinquent Loans
Financing Receivable, Past Due [Line Items]
Total Loans	$ 86