Allowance for Credit Losses - Accrued Interest Receivables (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Credit Loss [Abstract]
Loans	$ 259	$ 227
Securities held-to-maturity	57	20
Other financial assets measured at amortized cost	19	11
Securities available-for-sale	87	82
Total accrued interest receivables	422	340
Allowance for credit losses	0	0
Accrued interest receivables, net	$ 422	$ 340

Debt Securities, Available-for-Sale, Accrued Interest, Before Allowance For Credit Loss

No definition available.

Name:	hsbcusa_DebtSecuritiesAvailableForSaleAccruedInterestBeforeAllowanceForCreditLoss
Namespace Prefix:	hsbcusa_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Interest Receivable, Allowance For Credit Loss

+ References

No definition available.

+ Details

Name:	hsbcusa_InterestReceivableAllowanceForCreditLoss
Namespace Prefix:	hsbcusa_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Interest Receivables, Before Allowance For Credit Loss

+ References

No definition available.

+ Details

Name:	hsbcusa_InterestReceivablesBeforeAllowanceForCreditLoss
Namespace Prefix:	hsbcusa_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Other Financial Assets, Measured At Cost. Accrued Interest, Before Allowance For Credit Loss

+ References

No definition available.

+ Details

Name:	hsbcusa_OtherFinancialAssetsMeasuredAtCostAccruedInterestBeforeAllowanceForCreditLoss
Namespace Prefix:	hsbcusa_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

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

- Definition

Amount, before allowance for credit loss, of accrued interest on investment in debt security measured at amortized cost (held-to-maturity).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-3B

+ Details

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

- Definition

Amount, before allowance for credit loss, of accrued interest on financing receivable.

+ References

+ Details

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

- Definition

Carrying amount as of the balance sheet date of interest earned but not received. Also called accrued interest or accrued interest receivable.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 946
-SubTopic 310
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480833/946-310-45-1

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 210
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3)(a)(4))
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1

+ Details

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