Fee Income from Contracts with Customers - Disaggregation (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Disaggregation of Revenue [Line Items]
Other non-fee revenue (expense)	$ 91	$ (25)	$ 305	$ 93
Total other revenues	354	242	1,183	930
Total Fee Income
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	263	267	878	837
Credit card fees, net
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	10	0	37	23
Trust and investment management fees
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	39	26	99	81
Account services
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	67	73	204	216
Credit facilities
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	59	76	230	248
Other fees
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	10	11	40	32
Other fees and commissions
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	136	160	474	496
Servicing and other fees from HSBC affiliates
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	77	79	265	232
Insurance
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	$ 1	$ 2	$ 3	$ 5