Long-Term Debt - Schedule (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Long-term debt	[1]	$ 18,661	$ 17,591
Repayments of long-term debt		4,448	3,229	$ 10,044
HNAH
Debt Instrument [Line Items]
Long-term debt		6,500	6,000
HSBC USA
Debt Instrument [Line Items]
Long-term debt		15,739	14,747
Mark-to-market adjustment on fair value option debt		374	(334)
Repayments of long-term debt		4,435	3,089	$ 6,000
HSBC Bank USA and its Subsidiaries
Debt Instrument [Line Items]
Long-term debt		2,922	2,844
Mark-to-market adjustment on fair value option debt		6	(80)
Senior debt: | HSBC USA
Debt Instrument [Line Items]
Long-term debt		15,142	14,859
Senior debt: | HSBC Bank USA and its Subsidiaries
Debt Instrument [Line Items]
Long-term debt		1,475	1,483
Senior debt: | Fixed-rate notes | HSBC USA
Debt Instrument [Line Items]
Long-term debt		$ 9,165	7,261
Interest rate, weighted average		3.42%
Senior debt: | Fixed-rate notes | HSBC USA | Minimum
Debt Instrument [Line Items]
Interest rate, fixed		1.12%
Senior debt: | Fixed-rate notes | HSBC USA | Maximum
Debt Instrument [Line Items]
Interest rate, fixed		5.63%
Senior debt: | Structured notes | HSBC USA
Debt Instrument [Line Items]
Long-term debt		$ 5,977	7,598
Interest rate, weighted average		6.02%
Senior debt: | Structured notes | HSBC USA | Minimum
Debt Instrument [Line Items]
Interest rate, floating		5.40%
Senior debt: | Structured notes | HSBC USA | Maximum
Debt Instrument [Line Items]
Interest rate, floating		7.55%
Senior debt: | Structured notes | HSBC Bank USA and its Subsidiaries
Debt Instrument [Line Items]
Long-term debt		$ 441	453
Interest rate, weighted average		4.89%
Senior debt: | Structured notes | HSBC Bank USA and its Subsidiaries | Minimum
Debt Instrument [Line Items]
Interest rate, floating		3.04%
Senior debt: | Structured notes | HSBC Bank USA and its Subsidiaries | Maximum
Debt Instrument [Line Items]
Interest rate, floating		5.71%
Senior debt: | Floating Rate Notes | HSBC Bank USA and its Subsidiaries
Debt Instrument [Line Items]
Long-term debt		$ 34	30
Interest rate, weighted average		5.76%
Senior debt: | Floating Rate Notes | HSBC Bank USA and its Subsidiaries | Minimum
Debt Instrument [Line Items]
Interest rate, floating		5.48%
Senior debt: | Floating Rate Notes | HSBC Bank USA and its Subsidiaries | Maximum
Debt Instrument [Line Items]
Interest rate, floating		6.35%
Senior debt: | FHLB advances - floating-rate | HSBC Bank USA and its Subsidiaries
Debt Instrument [Line Items]
Long-term debt		$ 1,000	1,000
Interest rate, weighted average		5.72%
Interest rate, floating		5.72%
Subordinated debt: | Fixed-rate notes | HSBC USA
Debt Instrument [Line Items]
Long-term debt		$ 223	222
Interest rate, weighted average		7.20%
Interest rate, fixed		7.20%
Subordinated debt: | Fixed-rate notes | HSBC Bank USA and its Subsidiaries
Debt Instrument [Line Items]
Long-term debt		$ 1,441	$ 1,441
Interest rate, weighted average		6.36%
Subordinated debt: | Fixed-rate notes | HSBC Bank USA and its Subsidiaries | Minimum
Debt Instrument [Line Items]
Interest rate, fixed		5.63%
Subordinated debt: | Fixed-rate notes | HSBC Bank USA and its Subsidiaries | Maximum
Debt Instrument [Line Items]
Interest rate, fixed		7.00%

[1] The following table summarizes assets and liabilities related to our consolidated variable interest entities ("VIEs") at December 31, 2023 and 2022. Assets and liabilities exclude intercompany balances that eliminate in consolidation. See Note 27, "Variable Interest Entities," for additional information. At December 31,20232022(in millions)AssetsLoans, net$— $162 Other assets23 44 Total assets$23 $206 LiabilitiesInterest, taxes and other liabilities$17 $22 Total liabilities$17 $22