Loans - Credit Card Delinquency Status (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	$ 280,466	$ 277,340
Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	113,589	114,361
Revolving loans converted to term	373	411
Total	113,962	114,772
Domestic credit card: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	107,663	108,364
Revolving loans converted to term	324	359
Total	107,987	108,723
International card businesses: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	5,926	5,997
Revolving loans converted to term	49	52
Total	5,975	6,049
Current | Domestic credit card: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	105,190	105,985
Revolving loans converted to term	294	327
Total	105,484	106,312
Current | International card businesses: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	5,718	5,795
Revolving loans converted to term	38	41
Total	5,756	5,836
30-59 days | Domestic credit card: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	742	760
Revolving loans converted to term	12	13
Total	754	773
30-59 days | International card businesses: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	71	73
Revolving loans converted to term	4	4
Total	75	77
60-89 days | Domestic credit card: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	550	519
Revolving loans converted to term	8	9
Total	558	528
60-89 days | International card businesses: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	47	47
Revolving loans converted to term	3	3
Total	50	50
Greater than 90 days | Domestic credit card: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	1,181	1,100
Revolving loans converted to term	10	10
Total	1,191	1,110
Greater than 90 days | International card businesses: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	90	82
Revolving loans converted to term	4	4
Total	$ 94	$ 86