Loans - Loan Portfolio Composition and Aging Analysis (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Financing Receivable, Past Due [Line Items]
Current	$ 299,290	$ 302,305
Total	$ 308,836	$ 312,331
Current, percentage of total loans	96.91%	96.79%
Percentage of total loans	100.00%	100.00%
Unamortized premiums and discounts, deferred fees and costs	$ 1,400	$ 1,400
Credit Card
Financing Receivable, Past Due [Line Items]
Current	132,087	132,961
Total	137,142	137,730
Consumer Banking
Financing Receivable, Past Due [Line Items]
Current	73,883	74,985
Total	78,151	79,925
Consumer Banking | Auto
Financing Receivable, Past Due [Line Items]
Current	72,410	73,467
Total	76,652	78,373
Consumer Banking | Retail banking
Financing Receivable, Past Due [Line Items]
Current	1,473	1,518
Total	1,499	1,552
Commercial Banking
Financing Receivable, Past Due [Line Items]
Current	93,320	94,359
Total	93,543	94,676
Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Past Due [Line Items]
Current	37,096	37,417
Total	37,132	37,453
Commercial Banking | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Current	56,224	56,942
Total	$ 56,411	$ 57,223
30-59 days
Financing Receivable, Past Due [Line Items]
Past due, percentage of total loans	1.40%	1.50%
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 4,309	$ 4,666
30-59 days | Credit Card
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	1,495	1,491
30-59 days | Consumer Banking
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	2,778	3,114
30-59 days | Consumer Banking | Auto
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	2,771	3,101
30-59 days | Consumer Banking | Retail banking
Financing Receivable, Past Due [Line Items]
Total	7	13
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	7	13
30-59 days | Commercial Banking
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	36	61
30-59 days | Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	35	0
30-59 days | Commercial Banking | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 1	$ 61
60-89 days
Financing Receivable, Past Due [Line Items]
Past due, percentage of total loans	0.74%	0.80%
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 2,293	$ 2,511
60-89 days | Credit Card
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	1,092	1,033
60-89 days | Consumer Banking
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	1,174	1,422
60-89 days | Consumer Banking | Auto
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	1,171	1,418
60-89 days | Consumer Banking | Retail banking
Financing Receivable, Past Due [Line Items]
Total	3	4
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	3	4
60-89 days | Commercial Banking
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	27	56
60-89 days | Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	0	1
60-89 days | Commercial Banking | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 27	$ 55
Greater than 90 days
Financing Receivable, Past Due [Line Items]
Past due, percentage of total loans	0.95%	0.91%
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 2,944	$ 2,849
Greater than 90 days | Credit Card
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	2,468	2,245
Greater than 90 days | Consumer Banking
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	316	404
Greater than 90 days | Consumer Banking | Auto
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	300	387
Greater than 90 days | Consumer Banking | Retail banking
Financing Receivable, Past Due [Line Items]
Total	16	17
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	16	17
Greater than 90 days | Commercial Banking
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	160	200
Greater than 90 days | Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	1	35
Greater than 90 days | Commercial Banking | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 159	$ 165
Total Delinquent Loans
Financing Receivable, Past Due [Line Items]
Past due total, percentage of total loans	3.09%	3.21%
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 9,546	$ 10,026
Total Delinquent Loans | Credit Card
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	5,055	4,769
Total Delinquent Loans | Consumer Banking
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	4,268	4,940
Total Delinquent Loans | Consumer Banking | Auto
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	4,242	4,906
Total Delinquent Loans | Consumer Banking | Retail banking
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	26	34
Total Delinquent Loans | Commercial Banking
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	223	317
Total Delinquent Loans | Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	36	36
Total Delinquent Loans | Commercial Banking | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	187	281
Domestic credit card: | Credit Card
Financing Receivable, Past Due [Line Items]
Current	126,189	127,066
Total	130,980	131,581
Domestic credit card: | 30-59 days | Credit Card
Financing Receivable, Past Due [Line Items]
Total	1,406	1,405
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	1,406	1,405
Domestic credit card: | 60-89 days | Credit Card
Financing Receivable, Past Due [Line Items]
Total	1,033	975
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	1,033	975
Domestic credit card: | Greater than 90 days | Credit Card
Financing Receivable, Past Due [Line Items]
Total	2,352	2,135
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	2,352	2,135
Domestic credit card: | Total Delinquent Loans | Credit Card
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	4,791	4,515
International card businesses: | Credit Card
Financing Receivable, Past Due [Line Items]
Current	5,898	5,895
Total	6,162	6,149
International card businesses: | 30-59 days | Credit Card
Financing Receivable, Past Due [Line Items]
Total	89	86
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	89	86
International card businesses: | 60-89 days | Credit Card
Financing Receivable, Past Due [Line Items]
Total	59	58
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	59	58
International card businesses: | Greater than 90 days | Credit Card
Financing Receivable, Past Due [Line Items]
Total	116	110
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	116	110
International card businesses: | Total Delinquent Loans | Credit Card
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 264	$ 254