Loans - TDR - Subsequent Defaults (Details) $ in Millions	3 Months Ended
	Mar. 31, 2022 USD ($) contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	24,491
Total Loans | $	$ 94
Credit Card
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	22,519
Total Loans | $	$ 30
Consumer Banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	1,971
Total Loans | $	$ 33
Consumer Banking | Auto
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	1,971
Total Loans | $	$ 33
Consumer Banking | Retail banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	0
Total Loans | $	$ 0
Commercial Banking
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	1
Total Loans | $	$ 31
Commercial Banking | Commercial and industrial
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	1
Total Loans | $	$ 31
Domestic credit card: | Credit Card
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	6,012
Total Loans | $	$ 11
International card businesses: | Credit Card
Financing Receivable, Troubled Debt Restructuring [Line Items]
Number of Contracts | contract	16,507
Total Loans | $	$ 19