<?xml version="1.0" encoding="utf-8"?>
<FilingSummary xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <Version>2.4.0.6</Version>
  <ProcessingTime />
  <ReportFormat>Html</ReportFormat>
  <ContextCount>37</ContextCount>
  <ElementCount>142</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>4</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>3</UnitCount>
  <MyReports>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0001 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corninggas.com/role/DocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
    </Report>
    <Report>
      <IsDefault>true</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>0002 - Statement - Condensed Consolidated  Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corninggas.com/role/CondensedConsolidatedBalanceSheets</Role>
      <ShortName>Condensed Consolidated  Balance Sheets</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>0003 - Statement - Condensed Consolidated  Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corninggas.com/role/CondensedConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Condensed Consolidated  Balance Sheets (Parenthetical)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>0004 - Statement - Condensed Consolidated Statements of Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corninggas.com/role/CondensedConsolidatedStatementsOfIncome</Role>
      <ShortName>Condensed Consolidated Statements of Income</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>0005 - Statement - Consolidated Statements of Shareholders Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corninggas.com/role/ConsolidatedStatementsOfShareholdersEquity</Role>
      <ShortName>Consolidated Statements of Shareholders Equity</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>0006 - Statement - Consolidated Statements of Shareholders Equity (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corninggas.com/role/ConsolidatedStatementsOfShareholdersEquityParenthetical</Role>
      <ShortName>Consolidated Statements of Shareholders Equity (Parenthetical)</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>0007 - Statement - Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corninggas.com/role/ConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Consolidated Statements of Cash Flows</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>0008 - Disclosure - Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corninggas.com/role/SummaryOfSignificantAccountingPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>0009 - Disclosure - Major Customers</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corninggas.com/role/MajorCustomers</Role>
      <ShortName>Major Customers</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>0010 - Disclosure - Regulatory Matters</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corninggas.com/role/RegulatoryMatters</Role>
      <ShortName>Regulatory Matters</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>0011 - Disclosure - Long-term Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corninggas.com/role/Long-TermDebt</Role>
      <ShortName>Long-term Debt</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>0012 - Disclosure - Lines of Credit</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corninggas.com/role/LinesOfCredit</Role>
      <ShortName>Lines of Credit</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>0013 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corninggas.com/role/IncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>0014 - Disclosure - Pension and Other Post-retirement Benefit Plans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corninggas.com/role/PensionAndOtherPost-RetirementBenefitPlans</Role>
      <ShortName>Pension and Other Post-retirement Benefit Plans</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>0015 - Disclosure - Stock Options</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corninggas.com/role/StockOptions</Role>
      <ShortName>Stock Options</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>0016 - Disclosure - Commitments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://corninggas.com/role/Commitments</Role>
      <ShortName>Commitments</ShortName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <Logs>
    <Log type="Info">Process Flow-Through: 0002 - Statement - Condensed Consolidated  Balance Sheets</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Sep. 30, 2009'</Log>
    <Log type="Info">	Process Flow-Through: Removing column 'Sep. 30, 2008'</Log>
    <Log type="Info">Process Flow-Through: 0003 - Statement - Condensed Consolidated  Balance Sheets (Parenthetical)</Log>
    <Log type="Info">Process Flow-Through: 0004 - Statement - Condensed Consolidated Statements of Income</Log>
    <Log type="Info">Process Flow-Through: 0006 - Statement - Consolidated Statements of Shareholders Equity (Parenthetical)</Log>
    <Log type="Info">Process Flow-Through: 0007 - Statement - Consolidated Statements of Cash Flows</Log>
  </Logs>
  <InputFiles>
    <File>cnig-20110930.xml</File>
    <File>cnig-20110930.xsd</File>
    <File>cnig-20110930_cal.xml</File>
    <File>cnig-20110930_def.xml</File>
    <File>cnig-20110930_lab.xml</File>
    <File>cnig-20110930_pre.xml</File>
  </InputFiles>
  <SupplementalFiles />
  <BaseTaxonomies />
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
