Loans - TDR - Subsequent Defaults (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022 USD ($) contract	Sep. 30, 2021 USD ($) contract	Sep. 30, 2022 USD ($) contract	Sep. 30, 2021 USD ($) contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	33,490	19,001	89,145	64,707
Total Loans | $	$ 120	$ 96	$ 318	$ 361
Credit Card
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	28,898	16,848	79,040	58,237
Total Loans | $	$ 38	$ 24	$ 105	$ 93
Consumer Banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	4,592	2,152	10,102	6,462
Total Loans | $	$ 82	$ 34	$ 178	$ 98
Consumer Banking | Auto
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	4,592	2,151	10,102	6,453
Total Loans | $	$ 82	$ 34	$ 178	$ 98
Consumer Banking | Retail banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	0	1	0	9
Total Loans | $	$ 0	$ 0	$ 0	$ 0
Commercial Banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	0	1	3	8
Total Loans | $	$ 0	$ 38	$ 35	$ 170
Commercial Banking | Commercial And Industrial [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	0	1	3	7
Total Loans | $	$ 0	$ 38	$ 35	$ 120
Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	0	0	0	1
Total Loans | $	$ 0	$ 0	$ 0	$ 50
Domestic credit card: | Credit Card
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	9,927	4,168	23,951	13,528
Total Loans | $	$ 19	$ 7	$ 47	$ 25
International card businesses: | Credit Card
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	18,971	12,680	55,089	44,709
Total Loans | $	$ 19	$ 17	$ 58	$ 68