Loans - Loan Portfolio Composition and Aging Analysis (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Financing Receivable, Past Due [Line Items]
Current	$ 288,845	$ 270,655
Total	$ 296,384	$ 277,340
Current, percentage of total loans	97.46%	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	117,952	112,148
Total	120,880	114,772
Consumer Banking
Financing Receivable, Past Due [Line Items]
Current	77,606	74,028
Total	81,531	77,646
Consumer Banking | Auto
Financing Receivable, Past Due [Line Items]
Current	76,030	72,221
Total	79,926	75,779
Consumer Banking | Retail banking
Financing Receivable, Past Due [Line Items]
Current	1,576	1,807
Total	1,605	1,867
Commercial Banking
Financing Receivable, Past Due [Line Items]
Current	93,287	84,479
Total	93,973	84,922
Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Past Due [Line Items]
Current	37,507	35,100
Total	37,845	35,262
Commercial Banking | Commercial And Industrial [Member]
Financing Receivable, Past Due [Line Items]
Current	55,780	49,379
Total	$ 56,128	$ 49,660
30-59 days
Financing Receivable, Past Due [Line Items]
Past due, percentage of total loans	1.34%	1.26%
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 3,991	$ 3,501
30-59 days | Credit Card
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	978	850
30-59 days | Consumer Banking
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	2,576	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	2,566	2,385
30-59 days | Consumer Banking | Retail banking
Financing Receivable, Past Due [Line Items]
Total	10	35
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	10	35
30-59 days | Commercial Banking
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	437	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	212	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	$ 225	$ 139
60-89 days
Financing Receivable, Past Due [Line Items]
Past due, percentage of total loans	0.63%	0.60%
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 1,862	$ 1,656
60-89 days | Credit Card
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	663	578
60-89 days | Consumer Banking
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	1,085	940
60-89 days | Consumer Banking | Auto
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	1,084	933
60-89 days | Consumer Banking | Retail banking
Financing Receivable, Past Due [Line Items]
Total	1	7
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	1	7
60-89 days | Commercial Banking
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	114	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	70	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	$ 44	$ 103
Greater than 90 days
Financing Receivable, Past Due [Line Items]
Past due, percentage of total loans	0.57%	0.55%
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 1,686	$ 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	1,287	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	264	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	246	240
Greater than 90 days | Consumer Banking | Retail banking
Financing Receivable, Past Due [Line Items]
Total	18	18
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	18	18
Greater than 90 days | Commercial Banking
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	135	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	56	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	$ 79	$ 39
Financial Asset, Past Due
Financing Receivable, Past Due [Line Items]
Past due total, percentage of total loans	2.54%	2.41%
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	$ 7,539	$ 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	2,928	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	3,925	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	3,896	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	29	60
Financial Asset, Past Due | Commercial Banking
Financing Receivable, Past Due [Line Items]
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	686	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	338	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	348	281
Domestic credit card: | Credit Card
Financing Receivable, Past Due [Line Items]
Current	112,297	106,312
Total	115,004	108,723
Domestic credit card: | 30-59 days | Credit Card
Financing Receivable, Past Due [Line Items]
Total	896	773
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	896	773
Domestic credit card: | 60-89 days | Credit Card
Financing Receivable, Past Due [Line Items]
Total	615	528
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	615	528
Domestic credit card: | Greater than 90 days | Credit Card
Financing Receivable, Past Due [Line Items]
Total	1,196	1,110
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	1,196	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	2,707	2,411
International card businesses: | Credit Card
Financing Receivable, Past Due [Line Items]
Current	5,655	5,836
Total	5,876	6,049
International card businesses: | 30-59 days | Credit Card
Financing Receivable, Past Due [Line Items]
Total	82	77
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	82	77
International card businesses: | 60-89 days | Credit Card
Financing Receivable, Past Due [Line Items]
Total	48	50
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	48	50
International card businesses: | Greater than 90 days | Credit Card
Financing Receivable, Past Due [Line Items]
Total	91	86
Financing Receivable, Excluding Accrued Interest, before Allowance for Credit Loss, Noncurrent	91	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	$ 221	$ 213