Strategic Initiatives - Narrative (Details) $ in Millions	3 Months Ended	12 Months Ended			36 Months Ended
	Jun. 30, 2021 USD ($) branch	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2022
Restructuring Cost and Reserve [Line Items]
Impairment charges				$ 63
Derivative, Loss, Statement of Income or Comprehensive Income [Extensible Enumeration]				Trading revenue
Lease Termination and Associated Costs
Restructuring Cost and Reserve [Line Items]
Impairment charges		$ 22
Occupancy Expense, Net | Write Down Owned Office Space Properties to Fair Value
Restructuring Cost and Reserve [Line Items]
Impairment charges				$ 13
Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Expected period for completion of restructuring plan					3 years
Restructuring charges			$ 190	289
Trading losses associated with exit of certain derivative contracts				35
Allocated restructuring costs from affiliates			124	86
Restructuring Plan | Lease Termination and Associated Costs
Restructuring Cost and Reserve [Line Items]
Number of branches closed | branch	30
Impairment of Leasehold	$ 18
Restructuring Plan | Lease Termination and Associated Costs | Equipment
Restructuring Cost and Reserve [Line Items]
Impairment of long-lived assets to be disposed of	3
Restructuring Plan | Write Off Of Capitalized Software
Restructuring Cost and Reserve [Line Items]
Impairment charges			3
Restructuring Plan | Occupancy Expense, Net | Lease Termination and Associated Costs
Restructuring Cost and Reserve [Line Items]
Impairment charges	$ 29		10	40
HSBC Group Restructuring Activities
Restructuring Cost and Reserve [Line Items]
Allocated restructuring costs from affiliates			$ 131	$ 53