Loans - TDR - Subsequent Defaults (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022 USD ($) contract	Jun. 30, 2021 USD ($) contract	Jun. 30, 2022 USD ($) contract	Jun. 30, 2021 USD ($) contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	31,164	21,334	55,655	45,706
Total Loans | $	$ 104	$ 198	$ 198	$ 265
Credit Card
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	27,623	19,053	50,142	41,389
Total Loans | $	$ 37	$ 31	$ 67	$ 69
Consumer Banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	3,539	2,274	5,510	4,310
Total Loans | $	$ 63	$ 35	$ 96	$ 64
Consumer Banking | Auto
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	3,539	2,271	5,510	4,302
Total Loans | $	$ 63	$ 35	$ 96	$ 64
Consumer Banking | Retail banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	0	3	0	8
Total Loans | $	$ 0	$ 0	$ 0	$ 0
Commercial Banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	2	7	3	7
Total Loans | $	$ 4	$ 132	$ 35	$ 132
Commercial Banking | Commercial And Industrial [Member]
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	2	6	3	6
Total Loans | $	$ 4	$ 82	$ 35	$ 82
Commercial Banking | Commercial and multifamily real estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	0	1	0	1
Total Loans | $	$ 0	$ 50	$ 0	$ 50
Domestic credit card: | Credit Card
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	8,012	4,226	14,024	9,360
Total Loans | $	$ 17	$ 8	$ 28	$ 18
International card businesses: | Credit Card
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	19,611	14,827	36,118	32,029
Total Loans | $	$ 20	$ 23	$ 39	$ 51