Loans - Credit Card Delinquency Status (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	$ 277,340	$ 251,624
Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	114,361	106,323
Revolving loans converted to term	411	633
Total	114,772	106,956
Domestic credit card: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	108,364	97,969
Revolving loans converted to term	359	535
Total	108,723	98,504
International card businesses: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	5,997	8,354
Revolving loans converted to term	52	98
Total	6,049	8,452
Current | Domestic credit card: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	105,985	95,629
Revolving loans converted to term	327	487
Total	106,312	96,116
Current | International card businesses: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	5,795	8,152
Revolving loans converted to term	41	66
Total	5,836	8,218
30-59 days | Domestic credit card: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	760	734
Revolving loans converted to term	13	21
Total	773	755
30-59 days | International card businesses: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	73	79
Revolving loans converted to term	4	11
Total	77	90
60-89 days | Domestic credit card: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	519	451
Revolving loans converted to term	9	13
Total	528	464
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	11
Total	50	58
Greater than 90 days | Domestic credit card: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	1,100	1,155
Revolving loans converted to term	10	14
Total	1,110	1,169
Greater than 90 days | International card businesses: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans	82	76
Revolving loans converted to term	4	10
Total	$ 86	$ 86