3.3.0.814 html 1509 553 1 true 226 0 false 7 false false R1.htm 0001000 - Document - Document and Entity Information Sheet http://www.hsbcusa.com/role/DocumentAndEntityInformation Document and Entity Information Cover 1 false false R2.htm 1001000 - Statement - CONSOLIDATED STATEMENT OF INCOME (UNAUDITED) Sheet http://www.hsbcusa.com/role/ConsolidatedStatementOfIncomeUnaudited CONSOLIDATED STATEMENT OF INCOME (UNAUDITED) Statements 2 false false R3.htm 1001001 - Statement - CONSOLIDATED STATEMENT OF INCOME (UNAUDITED) (Parenthetical) Sheet http://www.hsbcusa.com/role/ConsolidatedStatementOfIncomeUnauditedParenthetical CONSOLIDATED STATEMENT OF INCOME (UNAUDITED) (Parenthetical) Statements 3 false false R4.htm 1002000 - Statement - CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (UNAUDITED) Sheet http://www.hsbcusa.com/role/ConsolidatedStatementOfComprehensiveIncomeUnaudited CONSOLIDATED STATEMENT OF COMPREHENSIVE INCOME (UNAUDITED) Statements 4 false false R5.htm 1003000 - Statement - CONSOLIDATED BALANCE SHEET (UNAUDITED) Sheet http://www.hsbcusa.com/role/ConsolidatedBalanceSheetUnaudited CONSOLIDATED BALANCE SHEET (UNAUDITED) Statements 5 false false R6.htm 1003501 - Statement - CONSOLIDATED BALANCE SHEET (UNAUDITED) (Parenthetical) Sheet http://www.hsbcusa.com/role/ConsolidatedBalanceSheetUnauditedParenthetical CONSOLIDATED BALANCE SHEET (UNAUDITED) (Parenthetical) Statements 6 false false R7.htm 1004000 - Statement - CONSOLIDATED STATEMENT OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) Sheet http://www.hsbcusa.com/role/ConsolidatedStatementOfChangesInShareholdersEquityUnaudited CONSOLIDATED STATEMENT OF CHANGES IN SHAREHOLDERS' EQUITY (UNAUDITED) Statements 7 false false R8.htm 1005000 - Statement - CONSOLIDATED STATEMENT OF CASH FLOWS (UNAUDITED) Sheet http://www.hsbcusa.com/role/ConsolidatedStatementOfCashFlowsUnaudited CONSOLIDATED STATEMENT OF CASH FLOWS (UNAUDITED) Statements 8 false false R9.htm 2101100 - Disclosure - Organization and Presentation Sheet http://www.hsbcusa.com/role/OrganizationAndPresentation Organization and Presentation Notes 9 false false R10.htm 2107100 - Disclosure - Trading Assets and Liabilities Sheet http://www.hsbcusa.com/role/TradingAssetsAndLiabilities Trading Assets and Liabilities Notes 10 false false R11.htm 2108100 - Disclosure - Securities Sheet http://www.hsbcusa.com/role/Securities Securities Notes 11 false false R12.htm 2109100 - Disclosure - Loans Sheet http://www.hsbcusa.com/role/Loans Loans Notes 12 false false R13.htm 2111100 - Disclosure - Allowance for Credit Losses Sheet http://www.hsbcusa.com/role/AllowanceForCreditLosses Allowance for Credit Losses Notes 13 false false R14.htm 2113100 - Disclosure - Loans Held for Sale Sheet http://www.hsbcusa.com/role/LoansHeldForSale Loans Held for Sale Notes 14 false false R15.htm 2117100 - Disclosure - Intangible Assets Sheet http://www.hsbcusa.com/role/IntangibleAssets Intangible Assets Notes 15 false false R16.htm 2119100 - Disclosure - Goodwill Sheet http://www.hsbcusa.com/role/Goodwill Goodwill Notes 16 false false R17.htm 2127100 - Disclosure - Derivative Financial Instruments Sheet http://www.hsbcusa.com/role/DerivativeFinancialInstruments Derivative Financial Instruments Notes 17 false false R18.htm 2129100 - Disclosure - Fair Value Option Sheet http://www.hsbcusa.com/role/FairValueOption Fair Value Option Notes 18 false false R19.htm 2135100 - Disclosure - Accumulated Other Comprehensive Income (Loss) Sheet http://www.hsbcusa.com/role/AccumulatedOtherComprehensiveIncomeLoss Accumulated Other Comprehensive Income (Loss) Notes 19 false false R20.htm 2139100 - Disclosure - Pension and Other Postretirement Benefits Sheet http://www.hsbcusa.com/role/PensionAndOtherPostretirementBenefits Pension and Other Postretirement Benefits Notes 20 false false R21.htm 2141100 - Disclosure - Related Party Transactions Sheet http://www.hsbcusa.com/role/RelatedPartyTransactions Related Party Transactions Notes 21 false false R22.htm 2143100 - Disclosure - Business Segments Sheet http://www.hsbcusa.com/role/BusinessSegments Business Segments Notes 22 false false R23.htm 2145100 - Disclosure - Retained Earnings and Regulatory Capital Requirements Sheet http://www.hsbcusa.com/role/RetainedEarningsAndRegulatoryCapitalRequirements Retained Earnings and Regulatory Capital Requirements Notes 23 false false R24.htm 2147100 - Disclosure - Variable Interest Entities Sheet http://www.hsbcusa.com/role/VariableInterestEntities Variable Interest Entities Notes 24 false false R25.htm 2149100 - Disclosure - Guarantee Arrangements, Pledged Assets and Repurchase Agreements Sheet http://www.hsbcusa.com/role/GuaranteeArrangementsPledgedAssetsAndRepurchaseAgreements Guarantee Arrangements, Pledged Assets and Repurchase Agreements Notes 25 false false R26.htm 2151100 - Disclosure - Fair Value Measurements Sheet http://www.hsbcusa.com/role/FairValueMeasurements Fair Value Measurements Notes 26 false false R27.htm 2153100 - Disclosure - Litigation and Regulatory Matters Sheet http://www.hsbcusa.com/role/LitigationAndRegulatoryMatters Litigation and Regulatory Matters Notes 27 false false R28.htm 2160100 - Disclosure - New Accounting Pronouncements Sheet http://www.hsbcusa.com/role/NewAccountingPronouncements New Accounting Pronouncements Notes 28 false false R29.htm 2251201 - Disclosure - Fair Value Measurements (Policies) Sheet http://www.hsbcusa.com/role/FairValueMeasurementsPolicies Fair Value Measurements (Policies) Policies http://www.hsbcusa.com/role/NewAccountingPronouncements 29 false false R30.htm 2307301 - Disclosure - Trading Assets and Liabilities (Tables) Sheet http://www.hsbcusa.com/role/TradingAssetsAndLiabilitiesTables Trading Assets and Liabilities (Tables) Tables http://www.hsbcusa.com/role/TradingAssetsAndLiabilities 30 false false R31.htm 2308301 - Disclosure - Securities (Tables) Sheet http://www.hsbcusa.com/role/SecuritiesTables Securities (Tables) Tables http://www.hsbcusa.com/role/Securities 31 false false R32.htm 2309301 - Disclosure - Loans (Tables) Sheet http://www.hsbcusa.com/role/LoansTables Loans (Tables) Tables http://www.hsbcusa.com/role/Loans 32 false false R33.htm 2311301 - Disclosure - Allowance for Credit Losses (Tables) Sheet http://www.hsbcusa.com/role/AllowanceForCreditLossesTables Allowance for Credit Losses (Tables) Tables http://www.hsbcusa.com/role/AllowanceForCreditLosses 33 false false R34.htm 2313301 - Disclosure - Loans Held for Sale (Tables) Sheet http://www.hsbcusa.com/role/LoansHeldForSaleTables Loans Held for Sale (Tables) Tables http://www.hsbcusa.com/role/LoansHeldForSale 34 false false R35.htm 2317301 - Disclosure - Intangible Assets (Tables) Sheet http://www.hsbcusa.com/role/IntangibleAssetsTables Intangible Assets (Tables) Tables http://www.hsbcusa.com/role/IntangibleAssets 35 false false R36.htm 2327301 - Disclosure - Derivative Financial Instruments (Tables) Sheet http://www.hsbcusa.com/role/DerivativeFinancialInstrumentsTables Derivative Financial Instruments (Tables) Tables http://www.hsbcusa.com/role/DerivativeFinancialInstruments 36 false false R37.htm 2329301 - Disclosure - Fair Value Option (Tables) Sheet http://www.hsbcusa.com/role/FairValueOptionTables Fair Value Option (Tables) Tables http://www.hsbcusa.com/role/FairValueOption 37 false false R38.htm 2335301 - Disclosure - Accumulated Other Comprehensive Income (Loss) (Tables) Sheet http://www.hsbcusa.com/role/AccumulatedOtherComprehensiveIncomeLossTables Accumulated Other Comprehensive Income (Loss) (Tables) Tables http://www.hsbcusa.com/role/AccumulatedOtherComprehensiveIncomeLoss 38 false false R39.htm 2339301 - Disclosure - Pension and Other Postretirement Benefits (Tables) Sheet http://www.hsbcusa.com/role/PensionAndOtherPostretirementBenefitsTables Pension and Other Postretirement Benefits (Tables) Tables http://www.hsbcusa.com/role/PensionAndOtherPostretirementBenefits 39 false false R40.htm 2341301 - Disclosure - Related Party Transactions (Tables) Sheet http://www.hsbcusa.com/role/RelatedPartyTransactionsTables Related Party Transactions (Tables) Tables http://www.hsbcusa.com/role/RelatedPartyTransactions 40 false false R41.htm 2343301 - Disclosure - Business Segments (Tables) Sheet http://www.hsbcusa.com/role/BusinessSegmentsTables Business Segments (Tables) Tables http://www.hsbcusa.com/role/BusinessSegments 41 false false R42.htm 2345301 - Disclosure - Retained Earnings and Regulatory Capital Requirements (Tables) Sheet http://www.hsbcusa.com/role/RetainedEarningsAndRegulatoryCapitalRequirementsTables Retained Earnings and Regulatory Capital Requirements (Tables) Tables http://www.hsbcusa.com/role/RetainedEarningsAndRegulatoryCapitalRequirements 42 false false R43.htm 2347301 - Disclosure - Variable Interest Entities (Tables) Sheet http://www.hsbcusa.com/role/VariableInterestEntitiesTables Variable Interest Entities (Tables) Tables http://www.hsbcusa.com/role/VariableInterestEntities 43 false false R44.htm 2349301 - Disclosure - Guarantee Arrangements, Pledged Assets and Repurchase Agreements (Tables) Sheet http://www.hsbcusa.com/role/GuaranteeArrangementsPledgedAssetsAndRepurchaseAgreementsTables Guarantee Arrangements, Pledged Assets and Repurchase Agreements (Tables) Tables http://www.hsbcusa.com/role/GuaranteeArrangementsPledgedAssetsAndRepurchaseAgreements 44 false false R45.htm 2351302 - Disclosure - Fair Value Measurements (Tables) Sheet http://www.hsbcusa.com/role/FairValueMeasurementsTables Fair Value Measurements (Tables) Tables http://www.hsbcusa.com/role/FairValueMeasurements 45 false false R46.htm 2407402 - Disclosure - Trading Assets and Liabilities (Details) Sheet http://www.hsbcusa.com/role/TradingAssetsAndLiabilitiesDetails Trading Assets and Liabilities (Details) Details http://www.hsbcusa.com/role/TradingAssetsAndLiabilitiesTables 46 false false R47.htm 2407403 - Disclosure - Trading Assets and Liabilities - Additional Information (Detail) Sheet http://www.hsbcusa.com/role/TradingAssetsAndLiabilitiesAdditionalInformationDetail Trading Assets and Liabilities - Additional Information (Detail) Details 47 false false R48.htm 2408402 - Disclosure - Securities - Amortized Cost and Fair Value of Asset Backed Securities (Detail) Sheet http://www.hsbcusa.com/role/SecuritiesAmortizedCostAndFairValueOfAssetBackedSecuritiesDetail Securities - Amortized Cost and Fair Value of Asset Backed Securities (Detail) Details 48 false false R49.htm 2408403 - Disclosure - Securities - Gross unrealized losses and related fair values (Detail) Sheet http://www.hsbcusa.com/role/SecuritiesGrossUnrealizedLossesAndRelatedFairValuesDetail Securities - Gross unrealized losses and related fair values (Detail) Details 49 false false R50.htm 2408404 - Disclosure - Securities - Other than Temporary Impairment, Credit Losses Recognized in Earnings (Details) Sheet http://www.hsbcusa.com/role/SecuritiesOtherThanTemporaryImpairmentCreditLossesRecognizedInEarningsDetails Securities - Other than Temporary Impairment, Credit Losses Recognized in Earnings (Details) Details 50 false false R51.htm 2408405 - Disclosure - Securities - Realized gains and losses on investment securities Transactions Attributable to available-for-sale securities (Detail) Sheet http://www.hsbcusa.com/role/SecuritiesRealizedGainsAndLossesOnInvestmentSecuritiesTransactionsAttributableToAvailableForSaleSecuritiesDetail Securities - Realized gains and losses on investment securities Transactions Attributable to available-for-sale securities (Detail) Details 51 false false R52.htm 2408406 - Disclosure - Securities - Distribution of maturities of debt securities with approximate yield of portfolio (Detail) Sheet http://www.hsbcusa.com/role/SecuritiesDistributionOfMaturitiesOfDebtSecuritiesWithApproximateYieldOfPortfolioDetail Securities - Distribution of maturities of debt securities with approximate yield of portfolio (Detail) Details 52 false false R53.htm 2408407 - Disclosure - Securities - Additional Information (Detail) Sheet http://www.hsbcusa.com/role/SecuritiesAdditionalInformationDetail Securities - Additional Information (Detail) Details 53 false false R54.htm 2409402 - Disclosure - Loans - Components of Loans (Details) Sheet http://www.hsbcusa.com/role/LoansComponentsOfLoansDetails Loans - Components of Loans (Details) Details 54 false false R55.htm 2409403 - Disclosure - Loans - Additional Information (Detail) Sheet http://www.hsbcusa.com/role/LoansAdditionalInformationDetail Loans - Additional Information (Detail) Details 55 false false R56.htm 2409404 - Disclosure - Loans - Summary of Past Due Status of Loans (Detail) Sheet http://www.hsbcusa.com/role/LoansSummaryOfPastDueStatusOfLoansDetail Loans - Summary of Past Due Status of Loans (Detail) Details 56 false false R57.htm 2409407 - Disclosure - Loans - Summary of Nonaccrual Loans and Accruing Receivables 90 Days or More Delinquent (Detail) Sheet http://www.hsbcusa.com/role/LoansSummaryOfNonaccrualLoansAndAccruingReceivables90DaysOrMoreDelinquentDetail Loans - Summary of Nonaccrual Loans and Accruing Receivables 90 Days or More Delinquent (Detail) Details 57 false false R58.htm 2409408 - Disclosure - Loans - Schedule of Additional Information on Nonaccrual Loans (Details) Sheet http://www.hsbcusa.com/role/LoansScheduleOfAdditionalInformationOnNonaccrualLoansDetails Loans - Schedule of Additional Information on Nonaccrual Loans (Details) Details 58 false false R59.htm 2409409 - Disclosure - Loans - Summary of Receivables which were Modified and as Result Became Classified as TDR Loans (Detail) Sheet http://www.hsbcusa.com/role/LoansSummaryOfReceivablesWhichWereModifiedAndAsResultBecameClassifiedAsTdrLoansDetail Loans - Summary of Receivables which were Modified and as Result Became Classified as TDR Loans (Detail) Details 59 false false R60.htm 2409410 - Disclosure - Loans - Summary of TDR and Related Credit Loss Reserves for TDR Loans (Detail) Sheet http://www.hsbcusa.com/role/LoansSummaryOfTdrAndRelatedCreditLossReservesForTdrLoansDetail Loans - Summary of TDR and Related Credit Loss Reserves for TDR Loans (Detail) Details 60 false false R61.htm 2409411 - Disclosure - Loans - Summary of TDR and Related Credit Loss Reserves for TDR Loans - Additional Information (Detail) Sheet http://www.hsbcusa.com/role/LoansSummaryOfTdrAndRelatedCreditLossReservesForTdrLoansAdditionalInformationDetail Loans - Summary of TDR and Related Credit Loss Reserves for TDR Loans - Additional Information (Detail) Details 61 false false R62.htm 2409412 - Disclosure - Loans - Trouble Debt Restructuring Additional Information (Detail) Sheet http://www.hsbcusa.com/role/LoansTroubleDebtRestructuringAdditionalInformationDetail Loans - Trouble Debt Restructuring Additional Information (Detail) Details 62 false false R63.htm 2409413 - Disclosure - Loans - Loans Classified as TDR Loans (Detail) Sheet http://www.hsbcusa.com/role/LoansLoansClassifiedAsTdrLoansDetail Loans - Loans Classified as TDR Loans (Detail) Details 63 false false R64.htm 2409414 - Disclosure - Loans - Impaired Commercial Loans Considered as TDR Loans (Detail) Sheet http://www.hsbcusa.com/role/LoansImpairedCommercialLoansConsideredAsTdrLoansDetail Loans - Impaired Commercial Loans Considered as TDR Loans (Detail) Details 64 false false R65.htm 2409415 - Disclosure - Loans - Average Balance and Interest Income Recognized on Impaired Commercial Loans (Detail) Sheet http://www.hsbcusa.com/role/LoansAverageBalanceAndInterestIncomeRecognizedOnImpairedCommercialLoansDetail Loans - Average Balance and Interest Income Recognized on Impaired Commercial Loans (Detail) Details 65 false false R66.htm 2409416 - Disclosure - Loans - Impaired Commercial Loans Considered as TDR Loans - Additional Information (Detail) Sheet http://www.hsbcusa.com/role/LoansImpairedCommercialLoansConsideredAsTdrLoansAdditionalInformationDetail Loans - Impaired Commercial Loans Considered as TDR Loans - Additional Information (Detail) Details 66 false false R67.htm 2409417 - Disclosure - Loans - Summary of Criticized Assets for Commercial Loans (Detail) Sheet http://www.hsbcusa.com/role/LoansSummaryOfCriticizedAssetsForCommercialLoansDetail Loans - Summary of Criticized Assets for Commercial Loans (Detail) Details 67 false false R68.htm 2409418 - Disclosure - Loans - Status of Commercial Loan Portfolio (Detail) Sheet http://www.hsbcusa.com/role/LoansStatusOfCommercialLoanPortfolioDetail Loans - Status of Commercial Loan Portfolio (Detail) Details 68 false false R69.htm 2409419 - Disclosure - Loans - Credit Risk Profile of Commercial Loans (Detail) Sheet http://www.hsbcusa.com/role/LoansCreditRiskProfileOfCommercialLoansDetail Loans - Credit Risk Profile of Commercial Loans (Detail) Details 69 false false R70.htm 2409420 - Disclosure - Loans - Delinquency Ratio for Consumer Loan (Detail) Sheet http://www.hsbcusa.com/role/LoansDelinquencyRatioForConsumerLoanDetail Loans - Delinquency Ratio for Consumer Loan (Detail) Details 70 false false R71.htm 2409421 - Disclosure - Loans - Delinquency Ratio for Consumer Loan - Additional Information (Detail) Sheet http://www.hsbcusa.com/role/LoansDelinquencyRatioForConsumerLoanAdditionalInformationDetail Loans - Delinquency Ratio for Consumer Loan - Additional Information (Detail) Details 71 false false R72.htm 2409422 - Disclosure - Loans - Status of Consumer Loan Portfolio (Detail) Sheet http://www.hsbcusa.com/role/LoansStatusOfConsumerLoanPortfolioDetail Loans - Status of Consumer Loan Portfolio (Detail) Details 72 false false R73.htm 2409423 - Disclosure - Loans - Concentration of Credit Risk (Details) Sheet http://www.hsbcusa.com/role/LoansConcentrationOfCreditRiskDetails Loans - Concentration of Credit Risk (Details) Details 73 false false R74.htm 2411402 - Disclosure - Allowance for Credit Losses - Summary of Changes in Allowance for Credit Losses and Related Loan Balance by Product (Detail) Sheet http://www.hsbcusa.com/role/AllowanceForCreditLossesSummaryOfChangesInAllowanceForCreditLossesAndRelatedLoanBalanceByProductDetail Allowance for Credit Losses - Summary of Changes in Allowance for Credit Losses and Related Loan Balance by Product (Detail) Details 74 false false R75.htm 2411403 - Disclosure - Allowance for Credit Losses - Summary of Changes in Allowance for Credit Losses and Related Loan Balance by Product - Additional Information (Detail) Sheet http://www.hsbcusa.com/role/AllowanceForCreditLossesSummaryOfChangesInAllowanceForCreditLossesAndRelatedLoanBalanceByProductAdditionalInformationDetail Allowance for Credit Losses - Summary of Changes in Allowance for Credit Losses and Related Loan Balance by Product - Additional Information (Detail) Details 75 false false R76.htm 2413402 - Disclosure - Loans Held for Sale (Details) Sheet http://www.hsbcusa.com/role/LoansHeldForSaleDetails Loans Held for Sale (Details) Details http://www.hsbcusa.com/role/LoansHeldForSaleTables 76 false false R77.htm 2413403 - Disclosure - Loans Held for Sale - Additional Information (Details) Sheet http://www.hsbcusa.com/role/LoansHeldForSaleAdditionalInformationDetails Loans Held for Sale - Additional Information (Details) Details 77 false false R78.htm 2417402 - Disclosure - Intangible Assets - Schedule of Intangible Assets (Detail) Sheet http://www.hsbcusa.com/role/IntangibleAssetsScheduleOfIntangibleAssetsDetail Intangible Assets - Schedule of Intangible Assets (Detail) Details 78 false false R79.htm 2417403 - Disclosure - Intangible Assets - Fair Value of Residential MSRs (Detail) Sheet http://www.hsbcusa.com/role/IntangibleAssetsFairValueOfResidentialMsrsDetail Intangible Assets - Fair Value of Residential MSRs (Detail) Details 79 false false R80.htm 2417404 - Disclosure - Intangible Assets - Residential MSRs Activity (Detail) Sheet http://www.hsbcusa.com/role/IntangibleAssetsResidentialMsrsActivityDetail Intangible Assets - Residential MSRs Activity (Detail) Details 80 false false R81.htm 2417405 - Disclosure - Intangible Assets - Additional Information (Detail) Sheet http://www.hsbcusa.com/role/IntangibleAssetsAdditionalInformationDetail Intangible Assets - Additional Information (Detail) Details 81 false false R82.htm 2419401 - Disclosure - Goodwill (Details) Sheet http://www.hsbcusa.com/role/GoodwillDetails Goodwill (Details) Details http://www.hsbcusa.com/role/Goodwill 82 false false R83.htm 2427402 - Disclosure - Derivative Financial Instruments - Fair Value of Derivatives and Balance Offsetting (Details) Sheet http://www.hsbcusa.com/role/DerivativeFinancialInstrumentsFairValueOfDerivativesAndBalanceOffsettingDetails Derivative Financial Instruments - Fair Value of Derivatives and Balance Offsetting (Details) Details 83 false false R84.htm 2427403 - Disclosure - Derivative Financial Instruments - Additional Information (Detail) Sheet http://www.hsbcusa.com/role/DerivativeFinancialInstrumentsAdditionalInformationDetail Derivative Financial Instruments - Additional Information (Detail) Details 84 false false R85.htm 2427404 - Disclosure - Derivative Financial Instruments - Gains and Losses on Hedged Items in Fair Value Hedges (Detail) Sheet http://www.hsbcusa.com/role/DerivativeFinancialInstrumentsGainsAndLossesOnHedgedItemsInFairValueHedgesDetail Derivative Financial Instruments - Gains and Losses on Hedged Items in Fair Value Hedges (Detail) Details 85 false false R86.htm 2427405 - Disclosure - Derivative Financial Instruments - Gains and Losses on Derivative Instruments Designated and Qualifying As Hedging Instruments in Cash Flow Hedges (Detail) Sheet http://www.hsbcusa.com/role/DerivativeFinancialInstrumentsGainsAndLossesOnDerivativeInstrumentsDesignatedAndQualifyingAsHedgingInstrumentsInCashFlowHedgesDetail Derivative Financial Instruments - Gains and Losses on Derivative Instruments Designated and Qualifying As Hedging Instruments in Cash Flow Hedges (Detail) Details 86 false false R87.htm 2427406 - Disclosure - Derivative Financial Instruments - Gains and Losses on Derivative Instruments Held For Trading Purpose (Detail) Sheet http://www.hsbcusa.com/role/DerivativeFinancialInstrumentsGainsAndLossesOnDerivativeInstrumentsHeldForTradingPurposeDetail Derivative Financial Instruments - Gains and Losses on Derivative Instruments Held For Trading Purpose (Detail) Details 87 false false R88.htm 2427407 - Disclosure - Derivative Financial Instruments - Gains and Losses on Derivative Instruments Held For Other Purpose (Detail) Sheet http://www.hsbcusa.com/role/DerivativeFinancialInstrumentsGainsAndLossesOnDerivativeInstrumentsHeldForOtherPurposeDetail Derivative Financial Instruments - Gains and Losses on Derivative Instruments Held For Other Purpose (Detail) Details 88 false false R89.htm 2427408 - Disclosure - Derivative Financial Instruments - Credit-Risk Related Contingent Features (Detail) Sheet http://www.hsbcusa.com/role/DerivativeFinancialInstrumentsCreditRiskRelatedContingentFeaturesDetail Derivative Financial Instruments - Credit-Risk Related Contingent Features (Detail) Details 89 false false R90.htm 2427409 - Disclosure - Derivative Financial Instruments - Notional Value of Derivative Contracts (Detail) Sheet http://www.hsbcusa.com/role/DerivativeFinancialInstrumentsNotionalValueOfDerivativeContractsDetail Derivative Financial Instruments - Notional Value of Derivative Contracts (Detail) Details 90 false false R91.htm 2429402 - Disclosure - Fair Value Option - Additional Information (Details) Sheet http://www.hsbcusa.com/role/FairValueOptionAdditionalInformationDetails Fair Value Option - Additional Information (Details) Details 91 false false R92.htm 2429403 - Disclosure - Fair Value Option - Summary of Fair Value and Unpaid Principal Balance (Details) Sheet http://www.hsbcusa.com/role/FairValueOptionSummaryOfFairValueAndUnpaidPrincipalBalanceDetails Fair Value Option - Summary of Fair Value and Unpaid Principal Balance (Details) Details 92 false false R93.htm 2429404 - Disclosure - Fair Value Option - Components of Gain (Loss) on Instruments at Fair Value and Related Derivatives (Detail) Sheet http://www.hsbcusa.com/role/FairValueOptionComponentsOfGainLossOnInstrumentsAtFairValueAndRelatedDerivativesDetail Fair Value Option - Components of Gain (Loss) on Instruments at Fair Value and Related Derivatives (Detail) Details 93 false false R94.htm 2435402 - Disclosure - Accumulated Other Comprehensive Income (Loss) - (Detail) Sheet http://www.hsbcusa.com/role/AccumulatedOtherComprehensiveIncomeLossDetail Accumulated Other Comprehensive Income (Loss) - (Detail) Details http://www.hsbcusa.com/role/AccumulatedOtherComprehensiveIncomeLossTables 94 false false R95.htm 2435403 - Disclosure - Accumulated Other Comprehensive Income (Loss) - Additional Information (Details) Sheet http://www.hsbcusa.com/role/AccumulatedOtherComprehensiveIncomeLossAdditionalInformationDetails Accumulated Other Comprehensive Income (Loss) - Additional Information (Details) Details http://www.hsbcusa.com/role/AccumulatedOtherComprehensiveIncomeLossTables 95 false false R96.htm 2439402 - Disclosure - Pension and Other Postretirement Benefits-Net Periodic Benefit Cost (Detail) Sheet http://www.hsbcusa.com/role/PensionAndOtherPostretirementBenefitsNetPeriodicBenefitCostDetail Pension and Other Postretirement Benefits-Net Periodic Benefit Cost (Detail) Details 96 false false R97.htm 2441402 - Disclosure - Related Party Transactions - Summary of Related Party Transactions (Details) Sheet http://www.hsbcusa.com/role/RelatedPartyTransactionsSummaryOfRelatedPartyTransactionsDetails Related Party Transactions - Summary of Related Party Transactions (Details) Details 97 false false R98.htm 2441403 - Disclosure - Related Party Transactions - Summary of Related Party Transactions (Income - Expense) (Details) Sheet http://www.hsbcusa.com/role/RelatedPartyTransactionsSummaryOfRelatedPartyTransactionsIncomeExpenseDetails Related Party Transactions - Summary of Related Party Transactions (Income - Expense) (Details) Details 98 false false R99.htm 2441404 - Disclosure - Related Party Transactions - Summary of Loans (Details) Sheet http://www.hsbcusa.com/role/RelatedPartyTransactionsSummaryOfLoansDetails Related Party Transactions - Summary of Loans (Details) Details 99 false false R100.htm 2441405 - Disclosure - Related Party Transactions - Additional Information (Details) Sheet http://www.hsbcusa.com/role/RelatedPartyTransactionsAdditionalInformationDetails Related Party Transactions - Additional Information (Details) Details 100 false false R101.htm 2443402 - Disclosure - Business Segments Additional Information (Details) Sheet http://www.hsbcusa.com/role/BusinessSegmentsAdditionalInformationDetails Business Segments Additional Information (Details) Details 101 false false R102.htm 2443403 - Disclosure - Business Segments - Summary on Reconciliation of Results Under Ifrs to Us Gaap (Detail) Sheet http://www.hsbcusa.com/role/BusinessSegmentsSummaryOnReconciliationOfResultsUnderIfrsToUsGaapDetail Business Segments - Summary on Reconciliation of Results Under Ifrs to Us Gaap (Detail) Details 102 false false R103.htm 2445402 - Disclosure - Retained Earnings and Regulatory Capital Requirements - Capital Amounts and Ratios in Accordance With Current Banking Regulations (Details) Sheet http://www.hsbcusa.com/role/RetainedEarningsAndRegulatoryCapitalRequirementsCapitalAmountsAndRatiosInAccordanceWithCurrentBankingRegulationsDetails Retained Earnings and Regulatory Capital Requirements - Capital Amounts and Ratios in Accordance With Current Banking Regulations (Details) Details 103 false false R104.htm 2445404 - Disclosure - Retained Earnings and Regulatory Capital Requirements - Additional Information (Details) Sheet http://www.hsbcusa.com/role/RetainedEarningsAndRegulatoryCapitalRequirementsAdditionalInformationDetails Retained Earnings and Regulatory Capital Requirements - Additional Information (Details) Details 104 false false R105.htm 2447402 - Disclosure - Variable Interest Entities - Summary of Assets and Liabilities Related to Consolidated Variable Interest Entities (Details) Sheet http://www.hsbcusa.com/role/VariableInterestEntitiesSummaryOfAssetsAndLiabilitiesRelatedToConsolidatedVariableInterestEntitiesDetails Variable Interest Entities - Summary of Assets and Liabilities Related to Consolidated Variable Interest Entities (Details) Details 105 false false R106.htm 2447403 - Disclosure - Variable Interest Entities - Variable Interests Held by Us and Our Maximum Exposure to Loss Rising From Our Involvements in Those VIEs (Details) Sheet http://www.hsbcusa.com/role/VariableInterestEntitiesVariableInterestsHeldByUsAndOurMaximumExposureToLossRisingFromOurInvolvementsInThoseViesDetails Variable Interest Entities - Variable Interests Held by Us and Our Maximum Exposure to Loss Rising From Our Involvements in Those VIEs (Details) Details 106 false false R107.htm 2447404 - Disclosure - Variable Interest Entities - Additional Information (Details) Sheet http://www.hsbcusa.com/role/VariableInterestEntitiesAdditionalInformationDetails Variable Interest Entities - Additional Information (Details) Details 107 false false R108.htm 2449402 - Disclosure - Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Carrying Value and Contractual Amounts of our Sell Protection Credit Derivatives and Major Off-Balance Sheet Guarantee Arrangements (Detail) Sheet http://www.hsbcusa.com/role/GuaranteeArrangementsPledgedAssetsAndRepurchaseAgreementsCarryingValueAndContractualAmountsOfOurSellProtectionCreditDerivativesAndMajorOffBalanceSheetGuaranteeArrangementsDetail Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Carrying Value and Contractual Amounts of our Sell Protection Credit Derivatives and Major Off-Balance Sheet Guarantee Arrangements (Detail) Details 108 false false R109.htm 2449403 - Disclosure - Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Carrying Value and Contractual Amounts of our Sell Protection Credit Derivatives and Major Off-Balance Sheet Guarantee Arrangements - Additional Information (Detail) Sheet http://www.hsbcusa.com/role/GuaranteeArrangementsPledgedAssetsAndRepurchaseAgreementsCarryingValueAndContractualAmountsOfOurSellProtectionCreditDerivativesAndMajorOffBalanceSheetGuaranteeArrangementsAdditionalInformationDetail Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Carrying Value and Contractual Amounts of our Sell Protection Credit Derivatives and Major Off-Balance Sheet Guarantee Arrangements - Additional Information (Detail) Details 109 false false R110.htm 2449404 - Disclosure - Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Net Credit Derivative Positions (Detail) Sheet http://www.hsbcusa.com/role/GuaranteeArrangementsPledgedAssetsAndRepurchaseAgreementsNetCreditDerivativePositionsDetail Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Net Credit Derivative Positions (Detail) Details 110 false false R111.htm 2449405 - Disclosure - Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Additional Information (Detail) Sheet http://www.hsbcusa.com/role/GuaranteeArrangementsPledgedAssetsAndRepurchaseAgreementsAdditionalInformationDetail Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Additional Information (Detail) Details 111 false false R112.htm 2449406 - Disclosure - Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Summary of Credit Ratings of Credit Risk Related Guarantees (Detail) Sheet http://www.hsbcusa.com/role/GuaranteeArrangementsPledgedAssetsAndRepurchaseAgreementsSummaryOfCreditRatingsOfCreditRiskRelatedGuaranteesDetail Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Summary of Credit Ratings of Credit Risk Related Guarantees (Detail) Details 112 false false R113.htm 2449407 - Disclosure - Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Summary of Change in Estimated Repurchase Liability for Loans Sold to GSEs and Other Third Parties (Detail) Sheet http://www.hsbcusa.com/role/GuaranteeArrangementsPledgedAssetsAndRepurchaseAgreementsSummaryOfChangeInEstimatedRepurchaseLiabilityForLoansSoldToGsesAndOtherThirdPartiesDetail Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Summary of Change in Estimated Repurchase Liability for Loans Sold to GSEs and Other Third Parties (Detail) Details 113 false false R114.htm 2449408 - Disclosure - Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Summary of Pledged Assets Included in Consolidated Balance Sheet (Detail) Sheet http://www.hsbcusa.com/role/GuaranteeArrangementsPledgedAssetsAndRepurchaseAgreementsSummaryOfPledgedAssetsIncludedInConsolidatedBalanceSheetDetail Guarantee Arrangements, Pledged Assets and Repurchase Agreements - Summary of Pledged Assets Included in Consolidated Balance Sheet (Detail) Details 114 false false R115.htm 2449410 - Disclosure - Guarantee Arrangements and Pledged Assets and Repurchase Agreements - Offsetting of Resale and Repurchase Agreements and Securities Borrowing and Lending Agreements (Details) Sheet http://www.hsbcusa.com/role/GuaranteeArrangementsAndPledgedAssetsAndRepurchaseAgreementsOffsettingOfResaleAndRepurchaseAgreementsAndSecuritiesBorrowingAndLendingAgreementsDetails Guarantee Arrangements and Pledged Assets and Repurchase Agreements - Offsetting of Resale and Repurchase Agreements and Securities Borrowing and Lending Agreements (Details) Details 115 false false R116.htm 2449411 - Disclosure - Guarantee Arrangements, Pledged Assets and Repurchase Agreements Guarantee Arrangements, Pledged Assets and Repurchase Agreements, Collateral Pledged and Remaining Contractual Maturity of Repurchase Agreements Accounted for as Secured Borrowings (Details) Sheet http://www.hsbcusa.com/role/GuaranteeArrangementsPledgedAssetsAndRepurchaseAgreementsGuaranteeArrangementsPledgedAssetsAndRepurchaseAgreementsCollateralPledgedAndRemainingContractualMaturityOfRepurchaseAgreementsAccountedForAsSecuredBorrowingsDetails Guarantee Arrangements, Pledged Assets and Repurchase Agreements Guarantee Arrangements, Pledged Assets and Repurchase Agreements, Collateral Pledged and Remaining Contractual Maturity of Repurchase Agreements Accounted for as Secured Borrowings (Details) Details 116 false false R117.htm 2451403 - Disclosure - Fair Value Measurements - Carrying Value and Estimated Fair Value of Financial Instruments (Detail) Sheet http://www.hsbcusa.com/role/FairValueMeasurementsCarryingValueAndEstimatedFairValueOfFinancialInstrumentsDetail Fair Value Measurements - Carrying Value and Estimated Fair Value of Financial Instruments (Detail) Details 117 false false R118.htm 2451404 - Disclosure - Fair Value Measurements - Assets and Liabilities Recorded at Fair Value on Recurring Basis (Detail) Sheet http://www.hsbcusa.com/role/FairValueMeasurementsAssetsAndLiabilitiesRecordedAtFairValueOnRecurringBasisDetail Fair Value Measurements - Assets and Liabilities Recorded at Fair Value on Recurring Basis (Detail) Details 118 false false R119.htm 2451405 - Disclosure - Fair Value Measurements - Additional Information (Detail) Sheet http://www.hsbcusa.com/role/FairValueMeasurementsAdditionalInformationDetail Fair Value Measurements - Additional Information (Detail) Details 119 false false R120.htm 2451406 - Disclosure - Fair Value Measurements - Changes in Fair Value of Level 3 Assets and Liabilities (Detail) Sheet http://www.hsbcusa.com/role/FairValueMeasurementsChangesInFairValueOfLevel3AssetsAndLiabilitiesDetail Fair Value Measurements - Changes in Fair Value of Level 3 Assets and Liabilities (Detail) Details 120 false false R121.htm 2451407 - Disclosure - Fair Value Measurements - Quantitative Information about Recurring Fair Value Measurement of Assets and Liabilities Classified as Level 3 (Detail) Sheet http://www.hsbcusa.com/role/FairValueMeasurementsQuantitativeInformationAboutRecurringFairValueMeasurementOfAssetsAndLiabilitiesClassifiedAsLevel3Detail Fair Value Measurements - Quantitative Information about Recurring Fair Value Measurement of Assets and Liabilities Classified as Level 3 (Detail) Details 121 false false R122.htm 2451408 - Disclosure - Fair Value Measurements - Assets and Liabilities Recorded as Fair Value on Nonrecurring Basis (Detail) Sheet http://www.hsbcusa.com/role/FairValueMeasurementsAssetsAndLiabilitiesRecordedAsFairValueOnNonrecurringBasisDetail Fair Value Measurements - Assets and Liabilities Recorded as Fair Value on Nonrecurring Basis (Detail) Details 122 false false R123.htm 2451409 - Disclosure - Fair Value Measurements - Quantitative Information about Nonrecurring Fair Value Measurement of Assets and Liabilities Classified as Level 3 (Detail) Sheet http://www.hsbcusa.com/role/FairValueMeasurementsQuantitativeInformationAboutNonrecurringFairValueMeasurementOfAssetsAndLiabilitiesClassifiedAsLevel3Detail Fair Value Measurements - Quantitative Information about Nonrecurring Fair Value Measurement of Assets and Liabilities Classified as Level 3 (Detail) Details 123 false false R124.htm 2451410 - Disclosure - Fair Value Measurements - Additional Information Relating To Asset-Backed Securities and Collateralized Debt Obligations (Detail) Sheet http://www.hsbcusa.com/role/FairValueMeasurementsAdditionalInformationRelatingToAssetBackedSecuritiesAndCollateralizedDebtObligationsDetail Fair Value Measurements - Additional Information Relating To Asset-Backed Securities and Collateralized Debt Obligations (Detail) Details 124 false false R125.htm 2453401 - Disclosure - Litigation and Regulatory Matters - Additional Information (Details) Sheet http://www.hsbcusa.com/role/LitigationAndRegulatoryMattersAdditionalInformationDetails Litigation and Regulatory Matters - Additional Information (Details) Details 125 false false All Reports Book All Reports In ''CONSOLIDATED BALANCE SHEET (UNAUDITED)'', column(s) 2, 4, 5, 6 are contained in other reports, so were removed by flow through suppression. In ''CONSOLIDATED BALANCE SHEET (UNAUDITED) (Parenthetical)'', column(s) 7 are contained in other reports, so were removed by flow through suppression. In ''CONSOLIDATED STATEMENT OF CASH FLOWS (UNAUDITED)'', column(s) 1, 2, 4 are contained in other reports, so were removed by flow through suppression. hsbcusa-20150930.xml hsbcusa-20150930_cal.xml hsbcusa-20150930_def.xml hsbcusa-20150930_lab.xml hsbcusa-20150930_pre.xml hsbcusa-20150930.xsd true true