Loans - Credit Card Delinquency Status (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	$ 308,836	$ 312,331
Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving Loans	136,786	137,394
Revolving Loans Converted to Term	356	336
Total	137,142	137,730
Domestic credit card: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving Loans	130,661	131,284
Revolving Loans Converted to Term	319	297
Total	130,980	131,581
International card businesses: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving Loans	6,125	6,110
Revolving Loans Converted to Term	37	39
Total	6,162	6,149
Current | Domestic credit card: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving Loans	125,911	126,811
Revolving Loans Converted to Term	278	255
Total	126,189	127,066
Current | International card businesses: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving Loans	5,869	5,866
Revolving Loans Converted to Term	29	29
Total	5,898	5,895
30-59 days | Domestic credit card: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving Loans	1,390	1,388
Revolving Loans Converted to Term	16	17
Total	1,406	1,405
30-59 days | International card businesses: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving Loans	86	83
Revolving Loans Converted to Term	3	3
Total	89	86
60-89 days | Domestic credit card: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving Loans	1,022	964
Revolving Loans Converted to Term	11	11
Total	1,033	975
60-89 days | International card businesses: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving Loans	57	55
Revolving Loans Converted to Term	2	3
Total	59	58
Greater than 90 days | Domestic credit card: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving Loans	2,338	2,121
Revolving Loans Converted to Term	14	14
Total	2,352	2,135
Greater than 90 days | International card businesses: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving Loans	113	106
Revolving Loans Converted to Term	3	4
Total	$ 116	$ 110