Loans - Credit Card Delinquency Status (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	$ 296,384	$ 277,340
Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	120,537	114,361
Revolving loans converted to term	343	411
Total	120,880	114,772
Domestic credit card: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	114,704	108,364
Revolving loans converted to term	300	359
Total	115,004	108,723
International card businesses: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	5,833	5,997
Revolving loans converted to term	43	52
Total	5,876	6,049
Current | Domestic credit card: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	112,027	105,985
Revolving loans converted to term	270	327
Total	112,297	106,312
Current | International card businesses: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	5,621	5,795
Revolving loans converted to term	34	41
Total	5,655	5,836
30-59 days | Domestic credit card: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	884	760
Revolving loans converted to term	12	13
Total	896	773
30-59 days | International card businesses: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	79	73
Revolving loans converted to term	3	4
Total	82	77
60-89 days | Domestic credit card: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	607	519
Revolving loans converted to term	8	9
Total	615	528
60-89 days | International card businesses: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	45	47
Revolving loans converted to term	3	3
Total	48	50
Greater than 90 days | Domestic credit card: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	1,186	1,100
Revolving loans converted to term	10	10
Total	1,196	1,110
Greater than 90 days | International card businesses: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	88	82
Revolving loans converted to term	3	4
Total	$ 91	$ 86