Credit card receivable balance associated with account relationships purchased.

No definition available.

Name:	husi_CreditCardReceivableBalanceAssociatedWithAccountRelationshipsPurchased
Namespace Prefix:	husi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of Intangible asset related to account relationships purchased include in branch sale.

+ References

No definition available.

+ Details

Name:	husi_FairValueOfIntangibleAssetRelatedToAccountRelationshipsPurchasedIncludeInBranchSale
Namespace Prefix:	husi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of Intangible asset related to account relationships purchased retained.

+ References

No definition available.

+ Details

Name:	husi_FairValueOfIntangibleAssetRelatedToAccountRelationshipsPurchasedRetained
Namespace Prefix:	husi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of intangible related to asset account relationships purchased.

+ References

No definition available.

+ Details

Name:	husi_FairValueOfIntangibleRelatedToAssetAccountRelationshipsPurchased
Namespace Prefix:	husi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Outstanding Principal Balances At Period End Of Residential Mortgage Loans Owned and Serviced For Others

+ References

No definition available.

+ Details

Name:	husi_OutstandingPrincipalBalancesAtPeriodEndOfResidentialMortgageLoansOwnedandServicedForOthers
Namespace Prefix:	husi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Outstanding principal balances at period end.

+ References

No definition available.

+ Details

Name:	husi_OutstandingPrincipalBalancesAtPeriodEndOfResidentialMortgageLoansServiceForOthers
Namespace Prefix:	husi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Residential mortgage banking revenue service fees.

+ References

No definition available.

+ Details

Name:	husi_ResidentialMortgageBankingRevenueServiceFees
Namespace Prefix:	husi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Long-lived assets that are held for sale apart from normal operations and anticipated to be sold in less than one year.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 205

-SubTopic 20

-Section 45

-Paragraph 10

-URI http://asc.fasb.org/extlink&oid=6892542&loc=d3e1107-107759

+ Details

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

- Details

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

- Definition

Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_FiniteLivedIntangibleAssetUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of gain (loss) on sale or disposal of intangible assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.7,9)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

+ Details

Name:	us-gaap_GainLossOnDispositionOfIntangibleAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The cash inflow from disposal of asset without physical form usually arising from contractual or other legal rights, excluding goodwill.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 12

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3179-108585

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Intangible Assets - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended		6 Months Ended				1 Months Ended	3 Months Ended
	Mar. 31, 2012	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013	Jun. 30, 2014 Mortgage Servicing Rights - Commercial Real Estate [Member]	Jul. 31, 2014 Subsequent Event [Member] Mortgage Servicing Rights - Commercial Real Estate [Member]	Sep. 30, 2014 Subsequent Event [Member] Mortgage Servicing Rights - Commercial Real Estate [Member]
Finite-Lived Intangible Assets [Line Items]
Outstanding principal balances at period end of residential mortgage loans serviced for others		$ 25,041		$ 25,041		$ 26,951
Residential mortgage banking revenue service fees		17	21	35	42
Outstanding principal balances at period end of residential mortgage loans owned and serviced for others		42,375		42,375		44,039
Assets held for sale							8
Proceeds from sale of Commercial MSRs								22
Gain on sale of Commercial MSRs									16
Purchased from HSBC Finance account of credit card	746
Credit card receivables not being sold to Capital One at a fair value	108
Fair value of Intangible asset related to account relationships purchased include in branch sale	43
Fair value of Intangible asset related to account relationships purchased retained	$ 65
Useful life	10 years