Fee Income from Contracts with Customers - Disaggregation (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenue [Line Items]
Other non-fee revenue	$ 223	$ 188
Total other revenues	539	453
Total Fee Income
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	316	265
Credit card fees, net
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	15	11
Trust and investment management fees
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	36	31
Account services
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	75	66
Credit facilities
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	91	73
Other fees
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	10	9
Other fees and commissions
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	176	148
Servicing and other fees from HSBC affiliates
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	88	74
Insurance
Disaggregation of Revenue [Line Items]
Total fee income from contracts with customers	$ 1	$ 1