Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Net Credit Derivative Positions (Detail) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Credit Derivatives [Line Items]
Net position, Carrying/Fair Value	$ (75)	$ (142)
Notional	8,137	10,726
Sell-protection credit derivative positions
Credit Derivatives [Line Items]
Carrying / Fair Value	86	54
Notional	3,900	2,992
Buy-protection credit derivative positions
Credit Derivatives [Line Items]
Carrying / Fair Value	(161)	(196)
Notional	$ 12,037	$ 13,718

Maximum potential amount of future undiscounted payments that could be required under the credit derivative, before reduction for potential recoveries under recourse or collateralization provisions.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4K
-Subparagraph (b)(1)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-4K

+ Details

Name:	us-gaap_CreditDerivativeMaximumExposureUndiscounted
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_CreditDerivativesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Fair value of credit risk derivative asset.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 50
-Paragraph 4K
-Subparagraph (c)
-SubTopic 10
-Topic 815
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480434/815-10-50-4K

+ Details

Name:	us-gaap_CreditRiskDerivativeAssetsAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of credit risk derivative liability.

+ References

+ Details

Name:	us-gaap_CreditRiskDerivativeLiabilitiesAtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value of credit risk derivative asset after deduction of credit risk derivative liability.

+ References

+ Details

Name:	us-gaap_CreditRiskDerivativesAtFairValueNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_CreditDerivativesByContractTypeAxis=hsbcusa_SellProtectionCreditDerivativesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditDerivativesByContractTypeAxis=hsbcusa_BuyProtectionCreditDerivativesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: