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, 2021	Dec. 31, 2020	Dec. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Interest cost on projected benefit obligation	$ 42	$ 45	$ 56
Expected return on plan assets	(58)	(68)	(78)
Amortization of net actuarial loss	0	4	21
Administrative costs	3	4	4
Pension (income) expense	$ (13)	$ (15)	$ 3