Pension and Other Postretirement Benefits - Net Periodic Benefit Cost (Detail) - HSBC North America - HSBC North America Pension Plan - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Interest cost on projected benefit obligation	$ 57	$ 52	$ 42
Expected return on plan assets	(65)	(56)	(58)
Amortization of net actuarial loss	5	3	0
Administrative costs	3	3	3
Pension (income) expense	$ 0	$ 2	$ (13)