Loans - Loan Portfolio Composition and Aging Analysis (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Financing Receivable, Past Due [Line Items]
Current	$ 300,858	$ 302,305
Total	$ 311,323	$ 312,331
Current, percentage of total loans	96.64%	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	137,118	132,961
Total	142,491	137,730
Consumer Banking:
Financing Receivable, Past Due [Line Items]
Current	72,680	74,985
Total	77,280	79,925
Consumer Banking: | Auto
Financing Receivable, Past Due [Line Items]
Current	71,273	73,467
Total	75,841	78,373
Consumer Banking: | Retail banking
Financing Receivable, Past Due [Line Items]
Current	1,407	1,518
Total	1,439	1,552
Commercial Portfolio
Financing Receivable, Past Due [Line Items]
Current	91,060	94,359
Total	91,552	94,676
Commercial Portfolio | Commercial and multifamily real estate
Financing Receivable, Past Due [Line Items]
Current	35,905	37,417
Total	36,041	37,453
Commercial Portfolio | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Current	55,155	56,942
Total	$ 55,511	$ 57,223
30-59 days
Financing Receivable, Past Due [Line Items]
Past due, percentage of total loans	1.48%	1.50%
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 4,601	$ 4,666
30-59 days | Credit Card:
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	1,657	1,491
30-59 days | Consumer Banking:
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	2,845	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	2,831	3,101
30-59 days | Consumer Banking: | Retail banking
Financing Receivable, Past Due [Line Items]
Total	14	13
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	14	13
30-59 days | Commercial Portfolio
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	99	61
30-59 days | Commercial Portfolio | Commercial and multifamily real estate
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	91	0
30-59 days | Commercial Portfolio | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 8	$ 61
60-89 days
Financing Receivable, Past Due [Line Items]
Past due, percentage of total loans	0.88%	0.80%
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 2,756	$ 2,511
60-89 days | Credit Card:
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	1,219	1,033
60-89 days | Consumer Banking:
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	1,374	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	1,370	1,418
60-89 days | Consumer Banking: | Retail banking
Financing Receivable, Past Due [Line Items]
Total	4	4
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	4	4
60-89 days | Commercial Portfolio
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	163	56
60-89 days | Commercial Portfolio | Commercial and multifamily real estate
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	40	1
60-89 days | Commercial Portfolio | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 123	$ 55
Greater than 90 days
Financing Receivable, Past Due [Line Items]
Past due, percentage of total loans	1.00%	0.91%
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 3,108	$ 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	2,497	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	381	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	367	387
Greater than 90 days | Consumer Banking: | Retail banking
Financing Receivable, Past Due [Line Items]
Total	14	17
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	14	17
Greater than 90 days | Commercial Portfolio
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	230	200
Greater than 90 days | Commercial Portfolio | Commercial and multifamily real estate
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	5	35
Greater than 90 days | Commercial Portfolio | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 225	$ 165
Total Delinquent Loans
Financing Receivable, Past Due [Line Items]
Past due total, percentage of total loans	3.36%	3.21%
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 10,465	$ 10,026
Total Delinquent Loans | Credit Card:
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	5,373	4,769
Total Delinquent Loans | Consumer Banking:
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	4,600	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	4,568	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	32	34
Total Delinquent Loans | Commercial Portfolio
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	492	317
Total Delinquent Loans | Commercial Portfolio | Commercial and multifamily real estate
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	136	36
Total Delinquent Loans | Commercial Portfolio | Commercial and industrial
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	356	281
Domestic credit card: | Credit Card:
Financing Receivable, Past Due [Line Items]
Current	130,886	127,066
Total	135,975	131,581
Domestic credit card: | 30-59 days | Credit Card:
Financing Receivable, Past Due [Line Items]
Total	1,554	1,405
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	1,554	1,405
Domestic credit card: | 60-89 days | Credit Card:
Financing Receivable, Past Due [Line Items]
Total	1,160	975
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	1,160	975
Domestic credit card: | Greater than 90 days | Credit Card:
Financing Receivable, Past Due [Line Items]
Total	2,375	2,135
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	2,375	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	5,089	4,515
International card businesses: | Credit Card:
Financing Receivable, Past Due [Line Items]
Current	6,232	5,895
Total	6,516	6,149
International card businesses: | 30-59 days | Credit Card:
Financing Receivable, Past Due [Line Items]
Total	103	86
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	103	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	122	110
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	122	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	$ 284	$ 254