Loans - Loan Portfolio Composition and Aging Analysis (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Financing Receivable, Past Due [Line Items]
Current	$ 302,305	$ 270,655
Total	$ 312,331	$ 277,340
Current, percentage of total loans	96.79%	97.59%
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	132,961	112,148
Total	137,730	114,772
Consumer Banking
Financing Receivable, Past Due [Line Items]
Current	74,985	74,028
Total	79,925	77,646
Consumer Banking | Auto
Financing Receivable, Past Due [Line Items]
Current	73,467	72,221
Total	78,373	75,779
Consumer Banking | Retail banking
Financing Receivable, Past Due [Line Items]
Current	1,518	1,807
Total	1,552	1,867
Commercial Banking
Financing Receivable, Past Due [Line Items]
Current	94,359	84,479
Total	94,676	84,922
Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Past Due [Line Items]
Current	37,417	35,100
Total	37,453	35,262
Commercial Banking | Commercial And Industrial [Member]
Financing Receivable, Past Due [Line Items]
Current	56,942	49,379
Total	$ 57,223	$ 49,660
30-59 days
Financing Receivable, Past Due [Line Items]
Past due, percentage of total loans	1.50%	1.26%
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 4,666	$ 3,501
30-59 days | Credit Card
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	1,491	850
30-59 days | Consumer Banking
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	3,114	2,420
30-59 days | Consumer Banking | Auto
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	3,101	2,385
30-59 days | Consumer Banking | Retail banking
Financing Receivable, Past Due [Line Items]
Total	13	35
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	13	35
30-59 days | Commercial Banking
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	61	231
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	0	92
30-59 days | Commercial Banking | Commercial And Industrial [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 61	$ 139
60-89 days
Financing Receivable, Past Due [Line Items]
Past due, percentage of total loans	0.80%	0.60%
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 2,511	$ 1,656
60-89 days | Credit Card
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	1,033	578
60-89 days | Consumer Banking
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	1,422	940
60-89 days | Consumer Banking | Auto
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	1,418	933
60-89 days | Consumer Banking | Retail banking
Financing Receivable, Past Due [Line Items]
Total	4	7
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	4	7
60-89 days | Commercial Banking
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	56	138
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	1	35
60-89 days | Commercial Banking | Commercial And Industrial [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 55	$ 103
Greater than 90 days
Financing Receivable, Past Due [Line Items]
Past due, percentage of total loans	0.91%	0.55%
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 2,849	$ 1,528
Greater than 90 days | Credit Card
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	2,245	1,196
Greater than 90 days | Consumer Banking
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	404	258
Greater than 90 days | Consumer Banking | Auto
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	387	240
Greater than 90 days | Consumer Banking | Retail banking
Financing Receivable, Past Due [Line Items]
Total	17	18
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	17	18
Greater than 90 days | Commercial Banking
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	200	74
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	35	35
Greater than 90 days | Commercial Banking | Commercial And Industrial [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 165	$ 39
Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Past due total, percentage of total loans	3.21%	2.41%
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 10,026	$ 6,685
Financial Asset, Past Due | Credit Card
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	4,769	2,624
Financial Asset, Past Due | Consumer Banking
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	4,940	3,618
Financial Asset, Past Due | Consumer Banking | Auto
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	4,906	3,558
Financial Asset, Past Due | Consumer Banking | Retail banking
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	34	60
Financial Asset, Past Due | Commercial Banking
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	317	443
Financial Asset, Past Due | 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	162
Financial Asset, Past Due | Commercial Banking | Commercial And Industrial [Member]
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	281	281
Domestic credit card: | Credit Card
Financing Receivable, Past Due [Line Items]
Current	127,066	106,312
Total	131,581	108,723
Domestic credit card: | 30-59 days | Credit Card
Financing Receivable, Past Due [Line Items]
Total	1,405	773
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	1,405	773
Domestic credit card: | 60-89 days | Credit Card
Financing Receivable, Past Due [Line Items]
Total	975	528
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	975	528
Domestic credit card: | Greater than 90 days | Credit Card
Financing Receivable, Past Due [Line Items]
Total	2,135	1,110
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	2,135	1,110
Domestic credit card: | Financial Asset, Past Due | Credit Card
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	4,515	2,411
International card businesses: | Credit Card
Financing Receivable, Past Due [Line Items]
Current	5,895	5,836
Total	6,149	6,049
International card businesses: | 30-59 days | Credit Card
Financing Receivable, Past Due [Line Items]
Total	86	77
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	86	77
International card businesses: | 60-89 days | Credit Card
Financing Receivable, Past Due [Line Items]
Total	58	50
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	58	50
International card businesses: | Greater than 90 days | Credit Card
Financing Receivable, Past Due [Line Items]
Total	110	86
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	110	86
International card businesses: | Financial Asset, Past Due | Credit Card
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 254	$ 213