Retained Earnings and Regulatory Capital Requirements - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Return of capital to parent	$ 0	$ 2,000	$ 1,000
HSBC Bank USA
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Capital contribution	17
Return of capital to parent	1,800
HNAH
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Return of capital to parent	$ 1,500