<?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>2.2.0.7</Version>
  <MyReports>
    <Report>
      <IsDefault>true</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>00 - Document - Document and Entity Information</LongName>
      <ShortName>Document and Entity Information</ShortName>
      <Role>http://wglholdings.com/role/DocumentAndEntityInformation</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R1.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>0110 - Statement - Consolidated Balance Sheets</LongName>
      <ShortName>Consolidated Balance Sheets</ShortName>
      <Role>http://wglholdings.com/role/BalanceSheets</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R2.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>0120 - Statement - Consolidated Statements of Income</LongName>
      <ShortName>Consolidated Statements of Income</ShortName>
      <Role>http://wglholdings.com/role/StatementsOfIncome</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R3.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>0130 - Statement - Consolidated Statements of Cash Flows</LongName>
      <ShortName>Consolidated Statements of Cash Flows</ShortName>
      <Role>http://wglholdings.com/role/StatementsOfCashFlows</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R4.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>0140 - Statement - Consolidated Statement of Capitalization</LongName>
      <ShortName>Consolidated Statement of Capitalization</ShortName>
      <Role>http://wglholdings.com/role/StatementOfCapitalization</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R5.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>0141 - Statement - Consolidated Statement of Capitalization (Parenthetical)</LongName>
      <ShortName>Consolidated Statement of Capitalization (Parenthetical)</ShortName>
      <Role>http://wglholdings.com/role/StatementOfCapitalizationParenthetical</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R6.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>0150 - Statement - Consolidated Statements of Common Shareholders Equity and Comprehensive Income</LongName>
      <ShortName>Consolidated Statements of Common Shareholders Equity and Comprehensive Income</ShortName>
      <Role>http://wglholdings.com/role/StatementsOfCommonShareholdersEquityAndComprehensiveIncome</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R7.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>0151 - Statement - Statements of Common Shareholders Equity and Comprehensive Income (Parenthetical)</LongName>
      <ShortName>Statements of Common Shareholders Equity and Comprehensive Income (Parenthetical)</ShortName>
      <Role>http://wglholdings.com/role/StatementsOfCommonShareholdersEquityAndComprehensiveIncomeParenthetical</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R8.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>0201 - Disclosure - Accounting Policies</LongName>
      <ShortName>Accounting Policies</ShortName>
      <Role>http://wglholdings.com/role/AccountingPolicies</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R9.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>0202 - Disclosure - Accounts Payable and Other Accrued Liabilities</LongName>
      <ShortName>Accounts Payable and Other Accrued Liabilities</ShortName>
      <Role>http://wglholdings.com/role/AccountsPayableAndOtherAccruedLiabilities</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R10.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>0203 - Disclosure - Short-Term Debt</LongName>
      <ShortName>Short-Term Debt</ShortName>
      <Role>http://wglholdings.com/role/ShortTermDebt</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R11.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>0204 - Disclosure - Long-Term Debt</LongName>
      <ShortName>Long-Term Debt</ShortName>
      <Role>http://wglholdings.com/role/LongTermDebt</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R12.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>0205 - Disclosure - Derivative and Weather-Related Instruments</LongName>
      <ShortName>Derivative and Weather-Related Instruments</ShortName>
      <Role>http://wglholdings.com/role/DerivativeAndWeatherRelatedInstruments</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R13.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>0206 - Disclosure - Common Stock - WGL Holdings</LongName>
      <ShortName>Common Stock - WGL Holdings</ShortName>
      <Role>http://wglholdings.com/role/CommonStock</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R14.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>0207 - Disclosure - Preferred Stock</LongName>
      <ShortName>Preferred Stock</ShortName>
      <Role>http://wglholdings.com/role/PreferredStock</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R15.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>0208 - Disclosure - Earnings Per Share</LongName>
      <ShortName>Earnings Per Share</ShortName>
      <Role>http://wglholdings.com/role/EarningsPerShare</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R16.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>0209 - Disclosure - Income Taxes</LongName>
      <ShortName>Income Taxes</ShortName>
      <Role>http://wglholdings.com/role/IncomeTaxes</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R17.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>0210 - Disclosure - Pension and Other Post-Retirement Benefit Plans</LongName>
      <ShortName>Pension and Other Post-Retirement Benefit Plans</ShortName>
      <Role>http://wglholdings.com/role/PensionAndOtherPostRetirementBenefitPlans</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R18.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>0211 - Disclosure - Stock-Based Compensation</LongName>
      <ShortName>Stock-Based Compensation</ShortName>
      <Role>http://wglholdings.com/role/StockBasedCompensation</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R19.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>0212 - Disclosure - Environmental Matters</LongName>
      <ShortName>Environmental Matters</ShortName>
      <Role>http://wglholdings.com/role/EnvironmentalMatters</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R20.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>0213 - Disclosure - Commitments and Contingencies</LongName>
      <ShortName>Commitments and Contingencies</ShortName>
      <Role>http://wglholdings.com/role/CommitmentsAndContingencies</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R21.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>0214 - Disclosure - Fair Value Measurements</LongName>
      <ShortName>Fair Value Measurements</ShortName>
      <Role>http://wglholdings.com/role/FairValueMeasurements</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R22.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>0215 - Disclosure - Operating Segment Reporting</LongName>
      <ShortName>Operating Segment Reporting</ShortName>
      <Role>http://wglholdings.com/role/OperatingSegmentReporting</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R23.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>0216 - Disclosure - Related Party Transactions</LongName>
      <ShortName>Related Party Transactions</ShortName>
      <Role>http://wglholdings.com/role/RelatedPartyTransactions</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R24.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Sheet</ReportType>
      <LongName>0301 - Schedule - Schedule II-Valuation and Qualifying Accounts and Reserves</LongName>
      <ShortName>Schedule II-Valuation and Qualifying Accounts and Reserves</ShortName>
      <Role>http://wglholdings.com/role/ValuationAndQualifyingAccountsAndReserves</Role>
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName>R25.xml</XmlFileName>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <ReportType>Book</ReportType>
      <LongName>All Reports</LongName>
      <ShortName>All Reports</ShortName>
      <Role />
      <ContainEmbeddedReports>false</ContainEmbeddedReports>
      <XmlFileName />
    </Report>
  </MyReports>
  <EntityCount>1</EntityCount>
  <ContextCount>153</ContextCount>
  <SegmentCount>23</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <UnitCount>4</UnitCount>
  <ElementCount>176</ElementCount>
  <FootnotesReported>true</FootnotesReported>
  <TuplesReported>false</TuplesReported>
  <ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Unsecured_Medium_Term_Notes_Due_In_Year_Fifteen_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Retained_Earnings_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Unsecured_Medium_Term_Notes_Due_In_Year_Six_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2010_Additional_Paid_In_Capital_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2009_Common_Stock_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_31Mar2010</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Retained_Earnings_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Additional_Paid_In_Capital_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_One_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Three_Member_Subsidiaries_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2010_Additional_Paid_In_Capital_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2010_Common_Stock_Member</ContextName>
      <ElementCount>4</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Subsidiaries_Member_Series_Three_Member</ContextName>
      <ElementCount>4</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Common_Stock_Member_Subsidiaries_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Four_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2010_Subsidiaries_Member_Unsecured_Medium_Term_Notes_Due_In_Year_Two_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Subsidiaries_Member_Series_Two_Member</ContextName>
      <ElementCount>4</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Subsidiaries_Member_Unsecured_Medium_Term_Notes_Due_In_Year_Fourteen_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2008_Common_Stock_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Twelve_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2008_Retained_Earnings_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Subsidiaries_Member_Series_One_Member</ContextName>
      <ElementCount>4</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Unsecured_Medium_Term_Notes_Due_In_Year_Thirteen_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2009_Accumulated_Other_Comprehensive_Income_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2007_Accumulated_Other_Comprehensive_Income_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2009_Retained_Earnings_Member</ContextName>
      <ElementCount>3</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Thirteen_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Ten_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Unsecured_Medium_Term_Notes_Due_In_Year_Four_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2008_Retained_Earnings_Member_Subsidiaries_Member</ContextName>
      <ElementCount>3</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Two_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Subsidiaries_Member_Unsecured_Medium_Term_Notes_Due_In_Year_Twelve_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010</ContextName>
      <ElementCount>64</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009</ContextName>
      <ElementCount>64</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2008_Additional_Paid_In_Capital_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2010_Retained_Earnings_Member_Subsidiaries_Member</ContextName>
      <ElementCount>3</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2008_Subsidiaries_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Fifteen_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2007_Additional_Paid_In_Capital_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2010_Subsidiaries_Member_Unsecured_Medium_Term_Notes_Due_In_Year_Thirteen_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2008_Common_Stock_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Additional_Paid_In_Capital_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Subsidiaries_Member_Unsecured_Medium_Term_Notes_Due_In_Year_Thirteen_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2009_Additional_Paid_In_Capital_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2010_Subsidiaries_Member</ContextName>
      <ElementCount>62</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2008_Accumulated_Other_Comprehensive_Income_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Retained_Earnings_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2009</ContextName>
      <ElementCount>68</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2007_Retained_Earnings_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Fifteen_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Unsecured_Medium_Term_Notes_Due_In_Year_One_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2010_Subsidiaries_Member_Unsecured_Medium_Term_Notes_Due_In_Year_Five_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Unsecured_Medium_Term_Notes_Due_In_Year_Ten_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Subsidiaries_Member_Series_Three_Member</ContextName>
      <ElementCount>4</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2009_Accumulated_Other_Comprehensive_Income_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Accumulated_Other_Comprehensive_Income_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2010_Accumulated_Other_Comprehensive_Income_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Unsecured_Medium_Term_Notes_Due_In_Year_Fourteen_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Two_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Series_Two_Member</ContextName>
      <ElementCount>4</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Unsecured_Medium_Term_Notes_Due_In_Year_Five_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Series_Two_Member</ContextName>
      <ElementCount>4</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Common_Stock_Member_Subsidiaries_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Subsidiaries_Member_Unsecured_Medium_Term_Notes_Due_In_Year_Ten_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Five_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2008</ContextName>
      <ElementCount>64</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2008_Retained_Earnings_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Accumulated_Other_Comprehensive_Income_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Six_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Common_Stock_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Three_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2010_Subsidiaries_Member_Unsecured_Medium_Term_Notes_Due_In_Year_Twelve_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2009_Additional_Paid_In_Capital_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2008_Additional_Paid_In_Capital_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Five_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2008_Subsidiaries_Member</ContextName>
      <ElementCount>58</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Series_Three_Member</ContextName>
      <ElementCount>4</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2010_Subsidiaries_Member_Unsecured_Medium_Term_Notes_Due_In_Year_Four_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2008_Additional_Paid_In_Capital_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Unsecured_Medium_Term_Notes_Due_In_Year_Nine_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Retained_Earnings_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Unsecured_Medium_Term_Notes_Due_In_Year_Seven_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2008_Accumulated_Other_Comprehensive_Income_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Accumulated_Other_Comprehensive_Income_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Subsidiaries_Member_Unsecured_Medium_Term_Notes_Due_In_Year_Fifteen_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Unsecured_Medium_Term_Notes_Due_In_Year_Seven_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2010_Retained_Earnings_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2008_Accumulated_Other_Comprehensive_Income_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Series_Three_Member</ContextName>
      <ElementCount>4</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Additional_Paid_In_Capital_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2007</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Two_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Additional_Paid_In_Capital_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Seven_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2007_Common_Stock_Member_Subsidiaries_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_One_Member_Subsidiaries_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Nine_Member_Subsidiaries_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2010_Accumulated_Other_Comprehensive_Income_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Six_Member_Subsidiaries_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2008_Retained_Earnings_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Subsidiaries_Member_Series_Two_Member</ContextName>
      <ElementCount>4</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Fourteen_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Four_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Eleven_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Series_One_Member</ContextName>
      <ElementCount>4</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Eight_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2007_Retained_Earnings_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Unsecured_Medium_Term_Notes_Due_In_Year_Two_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Series_One_Member</ContextName>
      <ElementCount>4</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Subsidiaries_Member_Unsecured_Medium_Term_Notes_Due_In_Year_Eleven_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Subsidiaries_Member_Unsecured_Medium_Term_Notes_Due_In_Year_Twelve_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2008_Common_Stock_Member_Subsidiaries_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2007_Additional_Paid_In_Capital_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Unsecured_Medium_Term_Notes_Due_In_Year_Twelve_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2008_Additional_Paid_In_Capital_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Unsecured_Medium_Term_Notes_Due_In_Year_Five_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2007_Common_Stock_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2007_Subsidiaries_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Seven_Member_Subsidiaries_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Subsidiaries_Member_Unsecured_Medium_Term_Notes_Due_In_Year_Eleven_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Unsecured_Medium_Term_Notes_Due_In_Year_Eight_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Thirteen_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Unsecured_Medium_Term_Notes_Due_In_Year_Three_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2010_Subsidiaries_Member_Unsecured_Medium_Term_Notes_Due_In_Year_Fifteen_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Unsecured_Medium_Term_Notes_Due_In_Year_Two_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Unsecured_Medium_Term_Notes_Due_In_Year_Four_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Unsecured_Medium_Term_Notes_Due_In_Year_Nine_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2008_Accumulated_Other_Comprehensive_Income_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Unsecured_Medium_Term_Notes_Due_In_Year_Eleven_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Unsecured_Medium_Term_Notes_Due_In_Year_Eight_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Subsidiaries_Member</ContextName>
      <ElementCount>64</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Subsidiaries_Member_Unsecured_Medium_Term_Notes_Due_In_Year_Fifteen_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Twelve_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Subsidiaries_Member_Unsecured_Medium_Term_Notes_Due_In_Year_Fourteen_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Subsidiaries_Member_Unsecured_Medium_Term_Notes_Due_In_Year_Thirteen_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Unsecured_Medium_Term_Notes_Due_In_Year_Six_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2008</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Accumulated_Other_Comprehensive_Income_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2009_Subsidiaries_Member</ContextName>
      <ElementCount>61</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>October-01-2009_September-30-2010</ContextName>
      <ElementCount>97</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Four_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Subsidiaries_Member_Series_One_Member</ContextName>
      <ElementCount>4</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Unsecured_Medium_Term_Notes_Due_In_Year_Three_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Subsidiaries_Member</ContextName>
      <ElementCount>64</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_31Oct2010</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>TwelveMonthsEnded_30Sep2009_Retained_Earnings_Member_Subsidiaries_Member</ContextName>
      <ElementCount>3</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Five_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Unsecured_Medium_Term_Notes_Due_In_Year_Nine_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Subsidiaries_Member_Unsecured_Medium_Term_Notes_Due_In_Year_Eight_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Subsidiaries_Member_Unsecured_Medium_Term_Notes_Due_In_Year_Ten_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2010_Common_Stock_Member</ContextName>
      <ElementCount>2</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2009_Unsecured_Medium_Term_Notes_Due_In_Year_One_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
    <ContextSummary>
      <ContextName>BalanceAsOf_30Sep2007_Accumulated_Other_Comprehensive_Income_Member_Subsidiaries_Member</ContextName>
      <ElementCount>1</ElementCount>
    </ContextSummary>
  </ContextSummary>
  <BaseTaxonomies />
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
