XML 200 R82.htm IDEA: XBRL DOCUMENT v2.4.1.9
Securities - Additional Information (Detail) (USD $)
 3 Months Ended 12 Months Ended
Dec. 31, 2014
security
Mar. 31, 2013
security
Dec. 31, 2014
security
Dec. 31, 2013
security
Dec. 31, 2012
Sep. 30, 2014
Schedule of Available-for-sale Securities [Line Items]            
Securities held-to-maturity $ 13,469,000,000us-gaap_HeldToMaturitySecurities   $ 13,469,000,000us-gaap_HeldToMaturitySecurities $ 1,358,000,000us-gaap_HeldToMaturitySecurities    
Non-Credit Loss Component of OTTI Securities, Held-to-Maturity Securities       104,000,000hsbcusa_HeldtoMaturitySecuritiesNonCreditLossComponentofOtherThanTemporarilyImpairedSecurities    
Assets backed securities in available for sale portfolio 15hsbcusa_AssetsBackedSecuritiesInAvailableForSalePortfolio   15hsbcusa_AssetsBackedSecuritiesInAvailableForSalePortfolio 22hsbcusa_AssetsBackedSecuritiesInAvailableForSalePortfolio    
Assets backed securities wrapped by monoline insurance company 5hsbcusa_AssetsBackedSecuritiesWrappedByInsuranceCompany   5hsbcusa_AssetsBackedSecuritiesWrappedByInsuranceCompany 8hsbcusa_AssetsBackedSecuritiesWrappedByInsuranceCompany    
Value of asset backed securities backed by insurance company 183,000,000hsbcusa_ValueOfAssetBackedSecuritiesBackedByInsuranceCompany   183,000,000hsbcusa_ValueOfAssetBackedSecuritiesBackedByInsuranceCompany 321,000,000hsbcusa_ValueOfAssetBackedSecuritiesBackedByInsuranceCompany    
Fair value of asset backed securities 226,000,000us-gaap_MortgageBackedSecuritiesAvailableForSaleFairValueDisclosure   226,000,000us-gaap_MortgageBackedSecuritiesAvailableForSaleFairValueDisclosure 448,000,000us-gaap_MortgageBackedSecuritiesAvailableForSaleFairValueDisclosure    
Available-for-sale securities, backed by insurance company, accumulated unrecognized holding loss 23,000,000hsbcusa_AvailableforsaleSecuritiesBackedbyInsuranceCompanyAccumulatedUnrecognizedHoldingLoss   23,000,000hsbcusa_AvailableforsaleSecuritiesBackedbyInsuranceCompanyAccumulatedUnrecognizedHoldingLoss 42,000,000hsbcusa_AvailableforsaleSecuritiesBackedbyInsuranceCompanyAccumulatedUnrecognizedHoldingLoss    
Fair value of financial guarantee 89,000,000hsbcusa_OtherThanTemporaryImpairmentWithFairValueFromFinancialGuaranteeFromInsuranceCompany   89,000,000hsbcusa_OtherThanTemporaryImpairmentWithFairValueFromFinancialGuaranteeFromInsuranceCompany 98,000,000hsbcusa_OtherThanTemporaryImpairmentWithFairValueFromFinancialGuaranteeFromInsuranceCompany    
Number of assets sold from held-to-maturity portfolio   6hsbcusa_NumberofAssetsSoldfromHeldtoMaturityPortfolio        
Sold security at carrying value   71,000,000us-gaap_HeldToMaturitySecuritiesSoldSecurityAtCarryingValue       76,000,000us-gaap_HeldToMaturitySecuritiesSoldSecurityAtCarryingValue
Gain (loss) on held-to-maturity securities 9,000,000us-gaap_HeldToMaturitySecuritiesSoldSecurityRealizedGainLoss 8,000,000us-gaap_HeldToMaturitySecuritiesSoldSecurityRealizedGainLoss (9,000,000)us-gaap_HeldToMaturitySecuritiesSoldSecurityRealizedGainLoss 8,000,000us-gaap_HeldToMaturitySecuritiesSoldSecurityRealizedGainLoss 0us-gaap_HeldToMaturitySecuritiesSoldSecurityRealizedGainLoss  
Asset backed securities [Member]            
Schedule of Available-for-sale Securities [Line Items]            
Securities held-to-maturity       200,000,000us-gaap_HeldToMaturitySecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= us-gaap_AssetBackedSecuritiesMember		    
Asset backed securities issued by consolidated VIE [Member]            
Schedule of Available-for-sale Securities [Line Items]            
Non-Credit Loss Component of OTTI Securities, Held-to-Maturity Securities       104,000,000hsbcusa_HeldtoMaturitySecuritiesNonCreditLossComponentofOtherThanTemporarilyImpairedSecurities
/ us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis
= hsbcusa_AssetbackedsecuritiesandotherdebtsecuritiesofVIEMember		 [1]    
Held-to-maturity Securities [Member]            
Schedule of Available-for-sale Securities [Line Items]            
Asset backed securities with changes to other than temporary impairment estimates related to credit component     2hsbcusa_AssetBackedSecuritiesWithChangestoOtherThanTemporaryImpairmentEstimatesRelatedtoCreditComponent
/ us-gaap_DebtSecurityAxis
= us-gaap_HeldtomaturitySecuritiesMember		 0hsbcusa_AssetBackedSecuritiesWithChangestoOtherThanTemporaryImpairmentEstimatesRelatedtoCreditComponent
/ us-gaap_DebtSecurityAxis
= us-gaap_HeldtomaturitySecuritiesMember		    
Increase in credit losses for which an other-than-temporary impairment was previously recognized     11,000,000us-gaap_OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsAdditionsAdditionalCreditLosses
/ us-gaap_DebtSecurityAxis
= us-gaap_HeldtomaturitySecuritiesMember		 0us-gaap_OtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsAdditionsAdditionalCreditLosses
/ us-gaap_DebtSecurityAxis
= us-gaap_HeldtomaturitySecuritiesMember		    
Other assets [Member]            
Schedule of Available-for-sale Securities [Line Items]            
Federal Home Loan Bank Stock 108,000,000us-gaap_FederalHomeLoanBankStock
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_OtherAssetsMember		   108,000,000us-gaap_FederalHomeLoanBankStock
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_OtherAssetsMember		 139,000,000us-gaap_FederalHomeLoanBankStock
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_OtherAssetsMember		    
Federal Reserve Bank Stock $ 483,000,000us-gaap_FederalReserveBankStock
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_OtherAssetsMember		   $ 483,000,000us-gaap_FederalReserveBankStock
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_OtherAssetsMember		 $ 483,000,000us-gaap_FederalReserveBankStock
/ us-gaap_BalanceSheetLocationAxis
= us-gaap_OtherAssetsMember		    
[1] Relates to securities held by Bryant Park Funding LLC ("Bryant Park"), a variable interest entity which was consolidated in 2013. During the fourth quarter of 2014, the securities underlying Bryant Park were sold and the related agreements were terminated. See Note 25, "Variable Interest Entities" for additional information.