Retained Earnings and Regulatory Capital Requirements - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Return of capital to parent		$ 1,000	$ 0	$ 2,400
HSBC USA
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Return of capital to parent	$ 1,000
HNAH
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Return of capital to parent	$ 1,000