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      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>090414 - Disclosure - Allowance for Loan Losses, Loans Modified as Troubled Debt Restructurings (Details)</LongName>
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      <LongName>090416 - Disclosure - Allowance for Loan Losses, Loans Modified or Renewed (Details)</LongName>
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      <ShortName>Allowance for Loan Losses, Loans Modified or Renewed (Details)</ShortName>
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    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>090418 - Disclosure - Allowance for Loan Losses (Details Textual)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/AllowanceForLoanLossesDetailsTextual</Role>
      <ShortName>Allowance for Loan Losses (Details Textual)</ShortName>
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      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.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>
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      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>090600 - Disclosure - Deposits (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/DepositsDetails</Role>
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    </Report>
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      <LongName>090700 - Disclosure - Borrowings (Details)</LongName>
      <ReportType>Sheet</ReportType>
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      <LongName>090800 - Disclosure - Stockholders' Equity (Details)</LongName>
      <ReportType>Sheet</ReportType>
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      <LongName>090900 - Disclosure - Income Taxes (Details)</LongName>
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    </Report>
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      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>091000 - Disclosure - Employee Benefits (Details)</LongName>
      <ReportType>Sheet</ReportType>
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      <ShortName>Employee Benefits (Details)</ShortName>
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      <LongName>091100 - Disclosure - Commitments and Contingent Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
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      <LongName>091200 - Disclosure - Regulatory Capital (Details)</LongName>
      <ReportType>Sheet</ReportType>
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      <ShortName>Regulatory Capital (Details)</ShortName>
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      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>091300 - Disclosure - Regulatory Agreement (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/RegulatoryAgreementDetails</Role>
      <ShortName>Regulatory Agreement (Details)</ShortName>
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    <Report>
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      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>091400 - Disclosure - Credit Concentrations (Details)</LongName>
      <ReportType>Sheet</ReportType>
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    <Report>
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      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>091500 - Disclosure - Fair Value of Financial Instruments (Details)</LongName>
      <ReportType>Sheet</ReportType>
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      <ShortName>Fair Value of Financial Instruments (Details)</ShortName>
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      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>091502 - Disclosure - Fair Value of Financial Instruments (1) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://suffolkbancorp.com/role/FairValueOfFinancialInstruments1Details</Role>
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      <LongName>091504 - Disclosure - Fair Value of Financial Instruments (2) (Details)</LongName>
      <ReportType>Sheet</ReportType>
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      <LongName>091506 - Disclosure - Fair Value of Financial Instruments (3) (Details)</LongName>
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      <Role>http://suffolkbancorp.com/role/FairValueOfFinancialInstruments3Details</Role>
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      <LongName>091508 - Disclosure - Fair Value of Financial Instruments (4) (Details)</LongName>
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      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>091600 - 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>
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      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>091700 - 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>
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    <Log type="Info">Process Flow-Through: 010000 - Statement - CONSOLIDATED STATEMENTS OF CONDITION</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2010'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Dec. 31, 2009'</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
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    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
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    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
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    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
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    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
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    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
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    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
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    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
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    <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
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    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
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    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
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    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
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    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
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    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
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    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
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    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
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    <Log type="Info">Process Flow-Through: 040100 - Statement - CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (Parenthetical)</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
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    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
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    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
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    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
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    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
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    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
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    <Log type="Info">	Process Flow-Through: Removing column '3 Months Ended
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    <Log type="Info">Process Flow-Through: 050000 - Statement - CONSOLIDATED STATEMENTS OF CASH FLOWS</Log>
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