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      <Role>http://suffolkbancorp.com/role/LoansSummaryOfNonperformingAssetsDetails</Role>
      <ShortName>LOANS, Summary of Non-Performing Assets (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>090412 - Disclosure - LOANS, Loans and Allowance for Loan Losses by Risk Rating (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/LoansLoansAndAllowanceForLoanLossesByRiskRatingDetails</Role>
      <ShortName>LOANS, Loans and Allowance for Loan Losses by Risk Rating (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>090414 - Disclosure - LOANS, Loans by Internal Assigned Grade for Credit Risk (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/LoansLoansByInternalAssignedGradeForCreditRiskDetails</Role>
      <ShortName>LOANS, Loans by Internal Assigned Grade for Credit Risk (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>090416 - Disclosure - LOANS, Loans Modified as Troubled Debt Restructurings (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/LoansLoansModifiedAsTroubledDebtRestructuringsDetails</Role>
      <ShortName>LOANS, Loans Modified as Troubled Debt Restructurings (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>090418 - Disclosure - LOANS, Loans Modified or Renewed (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/LoansLoansModifiedOrRenewedDetails</Role>
      <ShortName>LOANS, Loans Modified or Renewed (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>090420 - Disclosure - LOANS (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/LoansDetailsTextual</Role>
      <ShortName>LOANS (Details Textual)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>090500 - Disclosure - PREMISES AND EQUIPMENT (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/PremisesAndEquipmentDetails</Role>
      <ShortName>PREMISES AND EQUIPMENT (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>090600 - Disclosure - DEPOSITS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/DepositsDetails</Role>
      <ShortName>DEPOSITS (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>090700 - Disclosure - BORROWINGS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/BorrowingsDetails</Role>
      <ShortName>BORROWINGS (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>090800 - Disclosure - STOCKHOLDERS' EQUITY (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/StockholdersEquityDetails</Role>
      <ShortName>STOCKHOLDERS' EQUITY (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>090802 - Disclosure - STOCKHOLDERS' EQUITY, Stock Option Plans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/StockholdersEquityStockOptionPlansDetails</Role>
      <ShortName>STOCKHOLDERS' EQUITY, Stock Option Plans (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>090900 - Disclosure - INCOME TAXES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/IncomeTaxesDetails</Role>
      <ShortName>INCOME TAXES (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>091000 - Disclosure - EMPLOYEE BENEFITS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/EmployeeBenefitsDetails</Role>
      <ShortName>EMPLOYEE BENEFITS (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>091100 - Disclosure - COMMITMENTS AND CONTINGENT LIABILITIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/CommitmentsAndContingentLiabilitiesDetails</Role>
      <ShortName>COMMITMENTS AND CONTINGENT LIABILITIES (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>091200 - Disclosure - REGULATORY MATTERS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/RegulatoryMattersDetails</Role>
      <ShortName>REGULATORY MATTERS (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>091300 - Disclosure - CONCENTRATIONS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/ConcentrationsDetails</Role>
      <ShortName>CONCENTRATIONS (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>true</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>091400 - Disclosure - FAIR VALUE, Balance Sheets Grouping (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/FairValueBalanceSheetsGroupingDetails</Role>
      <ShortName>FAIR VALUE, Balance Sheets Grouping (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>091402 - Disclosure - FAIR VALUE, Non-recurring Basis (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/FairValueNonrecurringBasisDetails</Role>
      <ShortName>FAIR VALUE, Non-recurring Basis (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>091404 - Disclosure - FAIR VALUE, Recurring Basis (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/FairValueRecurringBasisDetails</Role>
      <ShortName>FAIR VALUE, Recurring Basis (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>091406 - Disclosure - FAIR VALUE, Reconciliations for Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Level 3) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/FairValueReconciliationsForAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisUsingSignificantUnobservableInputsLevel3Details</Role>
      <ShortName>FAIR VALUE, Reconciliations for Assets and Liabilities Measured at Fair Value on a Recurring Basis Using Significant Unobservable Inputs (Level 3) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>091500 - Disclosure - SUFFOLK BANCORP (PARENT COMPANY ONLY) CONDENSED FINANCIAL STATEMENTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/SuffolkBancorpParentCompanyOnlyCondensedFinancialStatementsDetails</Role>
      <ShortName>SUFFOLK BANCORP (PARENT COMPANY ONLY) CONDENSED FINANCIAL STATEMENTS (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>091600 - Disclosure - SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/SelectedQuarterlyFinancialDataUnauditedDetails</Role>
      <ShortName>SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>091700 - Disclosure - LEGAL PROCEEDINGS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/LegalProceedingsDetails</Role>
      <ShortName>LEGAL PROCEEDINGS (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>091800 - Disclosure - BRANCH CONSOLIDATION (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/BranchConsolidationDetails</Role>
      <ShortName>BRANCH CONSOLIDATION (Details)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <Logs>
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    <Log type="Info">Element us-gaap_FederalHomeLoanBankAdvancesActivityForYearAverageInterestRateAtPeriodEnd had a mix of decimals attribute values: 0 4.</Log>
    <Log type="Info">Element us-gaap_LoansAndLeasesReceivableImpairedTroubledDebtInterestIncome had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_RestructuringCharges had a mix of decimals attribute values: -5 -3.</Log>
    <Log type="Info">Element us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate had a mix of decimals attribute values: 3 4.</Log>
    <Log type="Info">Element us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate had a mix of decimals attribute values: 3 4.</Log>
    <Log type="Info">'Monetary' elements on report '090100 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '090302 - Disclosure - INVESTMENT SECURITIES, Amortized Cost, Maturities and Approximate Fair Value (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '090400 - Disclosure - LOANS (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '090414 - Disclosure - LOANS, Loans by Internal Assigned Grade for Credit Risk (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '090420 - Disclosure - LOANS (Details Textual)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '090500 - Disclosure - PREMISES AND EQUIPMENT (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '090700 - Disclosure - BORROWINGS (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '090900 - Disclosure - INCOME TAXES (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '091000 - Disclosure - EMPLOYEE BENEFITS (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '091100 - Disclosure - COMMITMENTS AND CONTINGENT LIABILITIES (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '091200 - Disclosure - REGULATORY MATTERS (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '091600 - Disclosure - SELECTED QUARTERLY FINANCIAL DATA (UNAUDITED) (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '091700 - Disclosure - LEGAL PROCEEDINGS (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">'Monetary' elements on report '091800 - Disclosure - BRANCH CONSOLIDATION (Details)' had a mix of different decimal attribute values.</Log>
    <Log type="Info">Process Flow-Through: 010000 - Statement - CONSOLIDATED STATEMENTS OF CONDITION</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2011'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2010'</Log>
    <Log type="Info">Process Flow-Through: 010100 - Statement - CONSOLIDATED STATEMENTS OF CONDITION (Parenthetical)</Log>
    <Log type="Info">Process Flow-Through: 020000 - Statement - CONSOLIDATED STATEMENTS OF OPERATIONS</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Dec. 31, 2013'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Sep. 30, 2013'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Jun. 30, 2013'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Mar. 31, 2013'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Dec. 31, 2012'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Sep. 30, 2012'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Jun. 30, 2012'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Mar. 31, 2012'</Log>
    <Log type="Info">Process Flow-Through: 030000 - Statement - CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (LOSS)</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Dec. 31, 2013'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Sep. 30, 2013'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Jun. 30, 2013'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Mar. 31, 2013'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Dec. 31, 2012'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Sep. 30, 2012'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Jun. 30, 2012'</Log>
    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
Mar. 31, 2012'</Log>
    <Log type="Info">Process Flow-Through: 040100 - Statement - CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical)</Log>
    <Log type="Info">Process Flow-Through: 050000 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS</Log>
  </Logs>
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    <File>subk-20131231.xsd</File>
    <File>subk-20131231_cal.xml</File>
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    <File>subk-20131231_lab.xml</File>
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