Fee Income from Contracts with Customers - Disaggregation (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation of Revenue [Line Items]
Other non-fee revenues	$ 49	$ 22	$ 214	$ 118
Total other revenues	343	304	829	688
Total Fee Income
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	294	282	615	570
Credit card fees, net
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	12	13	27	23
Trust and investment management fees
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	34	26	60	55
Account services
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	70	73	137	143
Credit facilities
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	71	89	171	172
Other fees
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	19	9	30	21
Other fees and commissions
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	160	171	338	336
Servicing and other fees from HSBC affiliates
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	87	70	188	153
Insurance
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	$ 1	$ 2	$ 2	$ 3