Strategic Initiatives - Branch Closings (Details) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)	Jun. 30, 2021 USD ($) branch	Sep. 30, 2022 USD ($)	Sep. 30, 2021 USD ($)
Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Trading losses associated with exit of certain derivative contracts		$ 22			$ 32
Allocated restructuring costs from affiliates	$ 25	13		$ 78	43
Restructuring Plan | Lease Termination and Associated Costs
Restructuring Cost and Reserve [Line Items]
Restructuring And Related Cost, 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 | Lease Termination and Associated Costs | Occupancy Expense, Net
Restructuring Cost and Reserve [Line Items]
Lease impairment charges	4	4	$ 29	1	9
HSBC Group Restructuring Activities
Restructuring Cost and Reserve [Line Items]
Allocated restructuring costs from affiliates	$ 36	$ 14		$ 78	$ 32