Retained Earnings and Regulatory Capital Requirements - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Return of capital to parent	$ 0	$ 0	$ 2,000
HSBC Bank USA
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Proceeds from common stock dividend received	1,100
HSBC North America
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Return of capital to parent	$ 100