Loans - Credit Card Delinquency Status (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Financing Receivable, Allowance for Credit Loss [Line Items]
Total	$ 311,323	$ 312,331
Credit Card:
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving Loans	142,119	137,394
Revolving Loans Converted to Term	372	336
Total	142,491	137,730
Domestic credit card: | Credit Card:
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving Loans	135,630	131,284
Revolving Loans Converted to Term	345	297
Total	135,975	131,581
International card businesses: | Credit Card:
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving Loans	6,489	6,110
Revolving Loans Converted to Term	27	39
Total	6,516	6,149
Current | Domestic credit card: | Credit Card:
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving Loans	130,591	126,811
Revolving Loans Converted to Term	295	255
Total	130,886	127,066
Current | International card businesses: | Credit Card:
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving Loans	6,209	5,866
Revolving Loans Converted to Term	23	29
Total	6,232	5,895
30-59 days | Domestic credit card: | Credit Card:
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving Loans	1,535	1,388
Revolving Loans Converted to Term	19	17
Total	1,554	1,405
30-59 days | International card businesses: | Credit Card:
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving Loans	101	83
Revolving Loans Converted to Term	2	3
Total	103	86
60-89 days | Domestic credit card: | Credit Card:
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving Loans	1,148	964
Revolving Loans Converted to Term	12	11
Total	1,160	975
60-89 days | International card businesses: | Credit Card:
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving Loans	58	55
Revolving Loans Converted to Term	1	3
Total	59	58
Greater than 90 days | Domestic credit card: | Credit Card:
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving Loans	2,356	2,121
Revolving Loans Converted to Term	19	14
Total	2,375	2,135
Greater than 90 days | International card businesses: | Credit Card:
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving Loans	121	106
Revolving Loans Converted to Term	1	4
Total	$ 122	$ 110