<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.10.0.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>440</ContextCount>
  <ElementCount>372</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>false</FootnotesReported>
  <SegmentCount>128</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>12</UnitCount>
  <MyReports>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>0001000 - Document - Document and Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/DocumentAndEntityInformation</Role>
      <ShortName>Document and Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>1001000 - Statement - Consolidated Balance Sheets</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/ConsolidatedBalanceSheets</Role>
      <ShortName>Consolidated Balance Sheets</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>1001501 - Statement - Consolidated Balance Sheets (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/ConsolidatedBalanceSheetsParenthetical</Role>
      <ShortName>Consolidated Balance Sheets (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>1002000 - Statement - Consolidated Statements of Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/ConsolidatedStatementsOfIncome</Role>
      <ShortName>Consolidated Statements of Income</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>1003000 - Statement - Consolidated Statements of Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/ConsolidatedStatementsOfComprehensiveIncome</Role>
      <ShortName>Consolidated Statements of Comprehensive Income</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>1003501 - Statement - Consolidated Statements of Comprehensive Income (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/ConsolidatedStatementsOfComprehensiveIncomeParenthetical</Role>
      <ShortName>Consolidated Statements of Comprehensive Income (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>1004000 - Statement - Consolidated Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/ConsolidatedStatementsOfCashFlows</Role>
      <ShortName>Consolidated Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>1005000 - Statement - Consolidated Statements of Stockholder's Equity</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/ConsolidatedStatementsOfStockholdersEquity</Role>
      <ShortName>Consolidated Statements of Stockholder's Equity</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>2101100 - Disclosure - Nature of Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/NatureOfOperations</Role>
      <ShortName>Nature of Operations</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>2102100 - Disclosure - Summary of Significant Accounting Policies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/SummaryOfSignificantAccountingPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>2104100 - Disclosure - Accounting Changes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/AccountingChanges</Role>
      <ShortName>Accounting Changes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>2106100 - Disclosure - Regulatory Assets and Liabilities and Regulatory Matters</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/RegulatoryAssetsAndLiabilitiesAndRegulatoryMatters</Role>
      <ShortName>Regulatory Assets and Liabilities and Regulatory Matters</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>2107100 - Disclosure - Inventories</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/Inventories</Role>
      <ShortName>Inventories</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>2108100 - Disclosure - Property, Plant and Equipment</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/PropertyPlantAndEquipment</Role>
      <ShortName>Property, Plant and Equipment</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>2109100 - Disclosure - Debt</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/Debt</Role>
      <ShortName>Debt</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>2110100 - Disclosure - Income Taxes</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/IncomeTaxes</Role>
      <ShortName>Income Taxes</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>2111100 - Disclosure - Employee Retirement Plans</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/EmployeeRetirementPlans</Role>
      <ShortName>Employee Retirement Plans</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>2112100 - Disclosure - Series Preferred Stock</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/SeriesPreferredStock</Role>
      <ShortName>Series Preferred Stock</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>2113100 - Disclosure - Equity-Based Compensation</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/EquityBasedCompensation</Role>
      <ShortName>Equity-Based Compensation</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>2114100 - Disclosure - Commitments and Contingencies</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/CommitmentsAndContingencies</Role>
      <ShortName>Commitments and Contingencies</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>2115100 - Disclosure - Fair Value Measurements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/FairValueMeasurements</Role>
      <ShortName>Fair Value Measurements</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>2116100 - Disclosure - Derivative Instruments and Hedging Activities</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/DerivativeInstrumentsAndHedgingActivities</Role>
      <ShortName>Derivative Instruments and Hedging Activities</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>22</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>2117100 - Disclosure - Accumulated Other Comprehensive Income</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/AccumulatedOtherComprehensiveIncome</Role>
      <ShortName>Accumulated Other Comprehensive Income</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>23</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>2118100 - Disclosure - Segment Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/SegmentInformation</Role>
      <ShortName>Segment Information</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>24</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>2119100 - Disclosure - Other Operating Income (Expense), Net</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/OtherOperatingIncomeExpenseNet</Role>
      <ShortName>Other Operating Income (Expense), Net</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>25</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>2120100 - Disclosure - Related Party Transactions</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/RelatedPartyTransactions</Role>
      <ShortName>Related Party Transactions</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>26</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>2121100 - Disclosure - Quarterly Data (unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/QuarterlyDataUnaudited</Role>
      <ShortName>Quarterly Data (unaudited)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>27</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>2122100 - Schedule - Schedule II - Valuation and Qualifying Accounts</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/ScheduleIiValuationAndQualifyingAccounts</Role>
      <ShortName>Schedule II - Valuation and Qualifying Accounts</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>28</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>2202201 - Disclosure - Summary of Significant Accounting Policies (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/SummaryOfSignificantAccountingPoliciesPolicies</Role>
      <ShortName>Summary of Significant Accounting Policies (Policies)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>2306301 - Disclosure - Regulatory Assets and Liabilities and Regulatory Matters (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/RegulatoryAssetsAndLiabilitiesAndRegulatoryMattersTables</Role>
      <ShortName>Regulatory Assets and Liabilities and Regulatory Matters (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>30</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>2307301 - Disclosure - Inventories (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/InventoriesTables</Role>
      <ShortName>Inventories (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>31</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>2308301 - Disclosure - Property, Plant and Equipment (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/PropertyPlantAndEquipmentTables</Role>
      <ShortName>Property, Plant and Equipment (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>32</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>2309301 - Disclosure - Debt (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/DebtTables</Role>
      <ShortName>Debt (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>33</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>2310301 - Disclosure - Income Taxes (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/IncomeTaxesTables</Role>
      <ShortName>Income Taxes (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>2311301 - Disclosure - Employee Retirement Plans (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/EmployeeRetirementPlansTables</Role>
      <ShortName>Employee Retirement Plans (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>2313301 - Disclosure - Equity-Based Compensation (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/EquityBasedCompensationTables</Role>
      <ShortName>Equity-Based Compensation (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>2315301 - Disclosure - Fair Value Measurements (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/FairValueMeasurementsTables</Role>
      <ShortName>Fair Value Measurements (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>2316301 - Disclosure - Derivative Instruments and Hedging Activities (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/DerivativeInstrumentsAndHedgingActivitiesTables</Role>
      <ShortName>Derivative Instruments and Hedging Activities (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R39.htm</HtmlFileName>
      <LongName>2317301 - Disclosure - Accumulated Other Comprehensive Income (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/AccumulatedOtherComprehensiveIncomeTables</Role>
      <ShortName>Accumulated Other Comprehensive Income (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>39</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R40.htm</HtmlFileName>
      <LongName>2318301 - Disclosure - Segment Information (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/SegmentInformationTables</Role>
      <ShortName>Segment Information (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>40</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R41.htm</HtmlFileName>
      <LongName>2319301 - Disclosure - Other Operating Income (Expense), Net (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/OtherOperatingIncomeExpenseNetTables</Role>
      <ShortName>Other Operating Income (Expense), Net (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>41</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R42.htm</HtmlFileName>
      <LongName>2321301 - Disclosure - Quarterly Data (unaudited) (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/QuarterlyDataUnauditedTables</Role>
      <ShortName>Quarterly Data (unaudited) (Tables)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>42</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R43.htm</HtmlFileName>
      <LongName>2401401 - Disclosure - Nature of Operations Nature of Operations (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/NatureOfOperationsNatureOfOperationsDetails</Role>
      <ShortName>Nature of Operations Nature of Operations (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>43</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R44.htm</HtmlFileName>
      <LongName>2402402 - Disclosure - Summary of Significant Accounting Policies - Property, Plant and Equipment and Related Depreciation (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/SummaryOfSignificantAccountingPoliciesPropertyPlantAndEquipmentAndRelatedDepreciationDetails</Role>
      <ShortName>Summary of Significant Accounting Policies - Property, Plant and Equipment and Related Depreciation (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>44</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R45.htm</HtmlFileName>
      <LongName>2402403 - Disclosure - Summary of Significant Accounting Policies - Goodwill (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/SummaryOfSignificantAccountingPoliciesGoodwillDetails</Role>
      <ShortName>Summary of Significant Accounting Policies - Goodwill (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>45</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R46.htm</HtmlFileName>
      <LongName>2402404 - Disclosure - Summary of Significant Accounting Policies - Impairment of Long-Lived Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/SummaryOfSignificantAccountingPoliciesImpairmentOfLongLivedAssetsDetails</Role>
      <ShortName>Summary of Significant Accounting Policies - Impairment of Long-Lived Assets (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>46</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R47.htm</HtmlFileName>
      <LongName>2406402 - Disclosure - Regulatory Assets and Liabilities and Regulatory Matters - Regulatory Assets and Liabilities Associated with Gas Utility and Electric Utility (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/RegulatoryAssetsAndLiabilitiesAndRegulatoryMattersRegulatoryAssetsAndLiabilitiesAssociatedWithGasUtilityAndElectricUtilityDetails</Role>
      <ShortName>Regulatory Assets and Liabilities and Regulatory Matters - Regulatory Assets and Liabilities Associated with Gas Utility and Electric Utility (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>47</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R48.htm</HtmlFileName>
      <LongName>2406403 - Disclosure - Regulatory Assets and Liabilities and Regulatory Matters - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/RegulatoryAssetsAndLiabilitiesAndRegulatoryMattersAdditionalInformationDetails</Role>
      <ShortName>Regulatory Assets and Liabilities and Regulatory Matters - Additional Information (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>48</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R49.htm</HtmlFileName>
      <LongName>2407402 - Disclosure - Inventories - Schedule of Inventories (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/InventoriesScheduleOfInventoriesDetails</Role>
      <ShortName>Inventories - Schedule of Inventories (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>49</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R50.htm</HtmlFileName>
      <LongName>2407403 - Disclosure - Inventories - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/InventoriesAdditionalInformationDetails</Role>
      <ShortName>Inventories - Additional Information (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>50</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R51.htm</HtmlFileName>
      <LongName>2408402 - Disclosure - Property, Plant and Equipment (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/PropertyPlantAndEquipmentDetails</Role>
      <ShortName>Property, Plant and Equipment (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>51</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R52.htm</HtmlFileName>
      <LongName>2409402 - Disclosure - Debt - Composition of Long Term Debt (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/DebtCompositionOfLongTermDebtDetails</Role>
      <ShortName>Debt - Composition of Long Term Debt (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>52</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R53.htm</HtmlFileName>
      <LongName>2409403 - Disclosure - Debt - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/DebtAdditionalInformationDetails</Role>
      <ShortName>Debt - Additional Information (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>53</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R54.htm</HtmlFileName>
      <LongName>2410402 - Disclosure - Income Taxes - Provisions for Income Taxes (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/IncomeTaxesProvisionsForIncomeTaxesDetails</Role>
      <ShortName>Income Taxes - Provisions for Income Taxes (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>54</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R55.htm</HtmlFileName>
      <LongName>2410403 - Disclosure - Income Taxes - Reconciliation from US Federal Statutory Tax Rate to Effective Tax Rate (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/IncomeTaxesReconciliationFromUsFederalStatutoryTaxRateToEffectiveTaxRateDetails</Role>
      <ShortName>Income Taxes - Reconciliation from US Federal Statutory Tax Rate to Effective Tax Rate (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>55</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R56.htm</HtmlFileName>
      <LongName>2410404 - Disclosure - Income Taxes - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/IncomeTaxesAdditionalInformationDetails</Role>
      <ShortName>Income Taxes - Additional Information (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>56</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R57.htm</HtmlFileName>
      <LongName>2410405 - Disclosure - Income Taxes - Deferred Tax Liabilities (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/IncomeTaxesDeferredTaxLiabilitiesDetails</Role>
      <ShortName>Income Taxes - Deferred Tax Liabilities (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>57</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R58.htm</HtmlFileName>
      <LongName>2410406 - Disclosure - Income Taxes - Reconciliation of Unrecognized Tax Benefits (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/IncomeTaxesReconciliationOfUnrecognizedTaxBenefitsDetails</Role>
      <ShortName>Income Taxes - Reconciliation of Unrecognized Tax Benefits (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>58</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R59.htm</HtmlFileName>
      <LongName>2411402 - Disclosure - Employee Retirement Plans - Change in Pension Benefits and Other Postretirement Benefit Obligations, Plan Assets, and Funded Status (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/EmployeeRetirementPlansChangeInPensionBenefitsAndOtherPostretirementBenefitObligationsPlanAssetsAndFundedStatusDetails</Role>
      <ShortName>Employee Retirement Plans - Change in Pension Benefits and Other Postretirement Benefit Obligations, Plan Assets, and Funded Status (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>59</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R60.htm</HtmlFileName>
      <LongName>2411403 - Disclosure - Employee Retirement Plans - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/EmployeeRetirementPlansAdditionalInformationDetails</Role>
      <ShortName>Employee Retirement Plans - Additional Information (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>60</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R61.htm</HtmlFileName>
      <LongName>2411404 - Disclosure - Employee Retirement Plans - Actuarial Assumptions for Domestic Plans (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/EmployeeRetirementPlansActuarialAssumptionsForDomesticPlansDetails</Role>
      <ShortName>Employee Retirement Plans - Actuarial Assumptions for Domestic Plans (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>61</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R62.htm</HtmlFileName>
      <LongName>2411405 - Disclosure - Employee Retirement Plans - Components of Net Periodic Pension Expense and Other Postretirement Benefit Costs (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/EmployeeRetirementPlansComponentsOfNetPeriodicPensionExpenseAndOtherPostretirementBenefitCostsDetails</Role>
      <ShortName>Employee Retirement Plans - Components of Net Periodic Pension Expense and Other Postretirement Benefit Costs (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>62</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R63.htm</HtmlFileName>
      <LongName>2411406 - Disclosure - Employee Retirement Plans - Expected Payments for Pension Benefits and Other Postretirement Welfare Benefits (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/EmployeeRetirementPlansExpectedPaymentsForPensionBenefitsAndOtherPostretirementWelfareBenefitsDetails</Role>
      <ShortName>Employee Retirement Plans - Expected Payments for Pension Benefits and Other Postretirement Welfare Benefits (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>63</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R64.htm</HtmlFileName>
      <LongName>2411407 - Disclosure - Employee Retirement Plans - Allocation of Pension Plan and VEBA Trust Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/EmployeeRetirementPlansAllocationOfPensionPlanAndVebaTrustAssetsDetails</Role>
      <ShortName>Employee Retirement Plans - Allocation of Pension Plan and VEBA Trust Assets (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>64</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R65.htm</HtmlFileName>
      <LongName>2411408 - Disclosure - Employee Retirement Plans - Fair Value of Pension Plan and VEBA Trust Assets (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/EmployeeRetirementPlansFairValueOfPensionPlanAndVebaTrustAssetsDetails</Role>
      <ShortName>Employee Retirement Plans - Fair Value of Pension Plan and VEBA Trust Assets (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>65</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R66.htm</HtmlFileName>
      <LongName>2412401 - Disclosure - Series Preferred Stock (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/SeriesPreferredStockDetails</Role>
      <ShortName>Series Preferred Stock (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>66</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R67.htm</HtmlFileName>
      <LongName>2413402 - Disclosure - Equity-Based Compensation - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/EquityBasedCompensationAdditionalInformationDetails</Role>
      <ShortName>Equity-Based Compensation - Additional Information (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>67</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R68.htm</HtmlFileName>
      <LongName>2413403 - Disclosure - Equity-Based Compensation - UGI Unit Award Activity (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/EquityBasedCompensationUgiUnitAwardActivityDetails</Role>
      <ShortName>Equity-Based Compensation - UGI Unit Award Activity (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>68</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R69.htm</HtmlFileName>
      <LongName>2414401 - Disclosure - Commitments and Contingencies - Commitments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/CommitmentsAndContingenciesCommitmentsDetails</Role>
      <ShortName>Commitments and Contingencies - Commitments (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>69</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R70.htm</HtmlFileName>
      <LongName>2414402 - Disclosure - Commitments and Contingencies - Contingencies (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/CommitmentsAndContingenciesContingenciesDetails</Role>
      <ShortName>Commitments and Contingencies - Contingencies (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>70</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R71.htm</HtmlFileName>
      <LongName>2415402 - Disclosure - Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/FairValueMeasurementsFinancialAssetsAndLiabilitiesMeasuredAtFairValueOnRecurringBasisDetails</Role>
      <ShortName>Fair Value Measurements - Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>71</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R72.htm</HtmlFileName>
      <LongName>2415403 - Disclosure - Fair Value Measurements - Long-term Debt (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/FairValueMeasurementsLongTermDebtDetails</Role>
      <ShortName>Fair Value Measurements - Long-term Debt (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>72</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R73.htm</HtmlFileName>
      <LongName>2416402 - Disclosure - Derivative Instruments and Hedging Activities - Additional Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/DerivativeInstrumentsAndHedgingActivitiesAdditionalInformationDetails</Role>
      <ShortName>Derivative Instruments and Hedging Activities - Additional Information (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>73</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R74.htm</HtmlFileName>
      <LongName>2416403 - Disclosure - Derivative Instruments and Hedging Activities - Derivative Assets and Liabilities Including Offsetting Amounts (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/DerivativeInstrumentsAndHedgingActivitiesDerivativeAssetsAndLiabilitiesIncludingOffsettingAmountsDetails</Role>
      <ShortName>Derivative Instruments and Hedging Activities - Derivative Assets and Liabilities Including Offsetting Amounts (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>74</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R75.htm</HtmlFileName>
      <LongName>2416404 - Disclosure - Derivative Instruments and Hedging Activities - Effects of Derivative Instruments on Consolidated Statements of Income and Changes in AOCI (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/DerivativeInstrumentsAndHedgingActivitiesEffectsOfDerivativeInstrumentsOnConsolidatedStatementsOfIncomeAndChangesInAociDetails</Role>
      <ShortName>Derivative Instruments and Hedging Activities - Effects of Derivative Instruments on Consolidated Statements of Income and Changes in AOCI (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>75</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R76.htm</HtmlFileName>
      <LongName>2417402 - Disclosure - Accumulated Other Comprehensive Income (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/AccumulatedOtherComprehensiveIncomeDetails</Role>
      <ShortName>Accumulated Other Comprehensive Income (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>76</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R77.htm</HtmlFileName>
      <LongName>2418402 - Disclosure - Segment Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/SegmentInformationDetails</Role>
      <ShortName>Segment Information (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>77</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R78.htm</HtmlFileName>
      <LongName>2419402 - Disclosure - Other Operating Income (Expense), Net (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/OtherOperatingIncomeExpenseNetDetails</Role>
      <ShortName>Other Operating Income (Expense), Net (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>78</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R79.htm</HtmlFileName>
      <LongName>2420401 - Disclosure - Related Party Transactions (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/RelatedPartyTransactionsDetails</Role>
      <ShortName>Related Party Transactions (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>79</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R80.htm</HtmlFileName>
      <LongName>2421402 - Disclosure - Quarterly Data (unaudited) (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/QuarterlyDataUnauditedDetails</Role>
      <ShortName>Quarterly Data (unaudited) (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>80</Position>
    </Report>
    <Report instance="ugu-20180930.xml">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R81.htm</HtmlFileName>
      <LongName>2422401 - Schedule - Schedule II - Valuation and Qualifying Accounts (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.ugi.com/role/ScheduleIiValuationAndQualifyingAccountsDetails</Role>
      <ShortName>Schedule II - Valuation and Qualifying Accounts (Details)</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>81</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>ugu-20180930.xml</File>
    <File>ugu-20180930.xsd</File>
    <File>ugu-20180930_cal.xml</File>
    <File>ugu-20180930_def.xml</File>
    <File>ugu-20180930_lab.xml</File>
    <File>ugu-20180930_pre.xml</File>
  </InputFiles>
  <SupplementalFiles/>
  <BaseTaxonomies>
    <BaseTaxonomy>http://xbrl.sec.gov/dei/2014-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/country/2017-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://fasb.org/us-gaap/2017-01-31</BaseTaxonomy>
    <BaseTaxonomy>http://xbrl.sec.gov/invest/2013-01-31</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
