<?xml version='1.0' encoding='utf-8'?>
<FilingSummary>
  <Version>3.24.0.1</Version>
  <ProcessingTime/>
  <ReportFormat>html</ReportFormat>
  <ContextCount>96</ContextCount>
  <ElementCount>195</ElementCount>
  <EntityCount>1</EntityCount>
  <FootnotesReported>true</FootnotesReported>
  <SegmentCount>44</SegmentCount>
  <ScenarioCount>0</ScenarioCount>
  <TuplesReported>false</TuplesReported>
  <UnitCount>6</UnitCount>
  <MyReports>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R1.htm</HtmlFileName>
      <LongName>00090 - Document - Document And Entity Information</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DocumentDocumentAndEntityInformation</Role>
      <ShortName>Document And Entity Information</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>1</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R2.htm</HtmlFileName>
      <LongName>00100 - Statement - Statements of Financial Condition</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/StatementStatementsOfFinancialCondition</Role>
      <ShortName>Statements of Financial Condition</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>2</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R3.htm</HtmlFileName>
      <LongName>00105 - Statement - Statements of Financial Condition (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/StatementStatementsOfFinancialConditionParenthetical</Role>
      <ShortName>Statements of Financial Condition (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>3</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R4.htm</HtmlFileName>
      <LongName>00200 - Statement - Schedule of Investments</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/StatementScheduleOfInvestments</Role>
      <ShortName>Schedule of Investments</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>4</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R5.htm</HtmlFileName>
      <LongName>00205 - Statement - Schedule of Investments (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/StatementScheduleOfInvestmentsParenthetical</Role>
      <ShortName>Schedule of Investments (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>5</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R6.htm</HtmlFileName>
      <LongName>00300 - Statement - Statements of Operations</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/StatementStatementsOfOperations</Role>
      <ShortName>Statements of Operations</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>6</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R7.htm</HtmlFileName>
      <LongName>00305 - Statement - Statements of Operations (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/StatementStatementsOfOperationsParenthetical</Role>
      <ShortName>Statements of Operations (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>7</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R8.htm</HtmlFileName>
      <LongName>00400 - Statement - Statements of Changes in Partners' Capital</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/StatementStatementsOfChangesInPartnersCapital</Role>
      <ShortName>Statements of Changes in Partners' Capital</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>8</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R9.htm</HtmlFileName>
      <LongName>00405 - Statement - Statements of Changes in Partners' Capital (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/StatementStatementsOfChangesInPartnersCapitalParenthetical</Role>
      <ShortName>Statements of Changes in Partners' Capital (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>9</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R10.htm</HtmlFileName>
      <LongName>00500 - Statement - Statements of Cash Flows</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/StatementStatementsOfCashFlows</Role>
      <ShortName>Statements of Cash Flows</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>10</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R11.htm</HtmlFileName>
      <LongName>00505 - Statement - Statements of Cash Flows (Parenthetical)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/StatementStatementsOfCashFlowsParenthetical</Role>
      <ShortName>Statements of Cash Flows (Parenthetical)</ShortName>
      <MenuCategory>Statements</MenuCategory>
      <Position>11</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R12.htm</HtmlFileName>
      <LongName>10101 - Disclosure - ORGANIZATION AND BUSINESS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureOrganizationAndBusiness</Role>
      <ShortName>ORGANIZATION AND BUSINESS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>12</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R13.htm</HtmlFileName>
      <LongName>10201 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureSummaryOfSignificantAccountingPolicies</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>13</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R14.htm</HtmlFileName>
      <LongName>10301 - Disclosure - FEES PAID BY THE FUND AND RELATED PARTY TRANSACTIONS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureFeesPaidByFundAndRelatedPartyTransactions</Role>
      <ShortName>FEES PAID BY THE FUND AND RELATED PARTY TRANSACTIONS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>14</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R15.htm</HtmlFileName>
      <LongName>10401 - Disclosure - CONTRACTS AND AGREEMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureContractsAndAgreements</Role>
      <ShortName>CONTRACTS AND AGREEMENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>15</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R16.htm</HtmlFileName>
      <LongName>10501 - Disclosure - FINANCIAL INSTRUMENTS, OFF-BALANCE SHEET RISKS AND CONTINGENCIES</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureFinancialInstrumentsOffBalanceSheetRisksAndContingencies</Role>
      <ShortName>FINANCIAL INSTRUMENTS, OFF-BALANCE SHEET RISKS AND CONTINGENCIES</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>16</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R17.htm</HtmlFileName>
      <LongName>10601 - Disclosure - FINANCIAL HIGHLIGHTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureFinancialHighlights</Role>
      <ShortName>FINANCIAL HIGHLIGHTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>17</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R18.htm</HtmlFileName>
      <LongName>10701 - Disclosure - QUARTERLY FINANCIAL DATA (Unaudited)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureQuarterlyFinancialDataUnaudited</Role>
      <ShortName>QUARTERLY FINANCIAL DATA (Unaudited)</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>18</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R19.htm</HtmlFileName>
      <LongName>10801 - Disclosure - FAIR VALUE OF FINANCIAL INSTRUMENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureFairValueOfFinancialInstruments</Role>
      <ShortName>FAIR VALUE OF FINANCIAL INSTRUMENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>19</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R20.htm</HtmlFileName>
      <LongName>10901 - Disclosure - SUBSEQUENT EVENTS</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureSubsequentEvents</Role>
      <ShortName>SUBSEQUENT EVENTS</ShortName>
      <MenuCategory>Notes</MenuCategory>
      <Position>20</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R21.htm</HtmlFileName>
      <LongName>20202 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureSummaryOfSignificantAccountingPoliciesPolicies</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)</ShortName>
      <MenuCategory>Policies</MenuCategory>
      <Position>21</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R22.htm</HtmlFileName>
      <LongName>30403 - Disclosure - CONTRACTS AND AGREEMENTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureContractsAndAgreementsTables</Role>
      <ShortName>CONTRACTS AND AGREEMENTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.unitedstatesnaturalgasfund.com/role/DisclosureContractsAndAgreements</ParentRole>
      <Position>22</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R23.htm</HtmlFileName>
      <LongName>30603 - Disclosure - FINANCIAL HIGHLIGHTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureFinancialHighlightsTables</Role>
      <ShortName>FINANCIAL HIGHLIGHTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.unitedstatesnaturalgasfund.com/role/DisclosureFinancialHighlights</ParentRole>
      <Position>23</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R24.htm</HtmlFileName>
      <LongName>30703 - Disclosure - QUARTERLY FINANCIAL DATA (Unaudited) (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureQuarterlyFinancialDataUnauditedTables</Role>
      <ShortName>QUARTERLY FINANCIAL DATA (Unaudited) (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.unitedstatesnaturalgasfund.com/role/DisclosureQuarterlyFinancialDataUnaudited</ParentRole>
      <Position>24</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R25.htm</HtmlFileName>
      <LongName>30803 - Disclosure - FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureFairValueOfFinancialInstrumentsTables</Role>
      <ShortName>FAIR VALUE OF FINANCIAL INSTRUMENTS (Tables)</ShortName>
      <MenuCategory>Tables</MenuCategory>
      <ParentRole>http://www.unitedstatesnaturalgasfund.com/role/DisclosureFairValueOfFinancialInstruments</ParentRole>
      <Position>25</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R26.htm</HtmlFileName>
      <LongName>40101 - Disclosure - ORGANIZATION AND BUSINESS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureOrganizationAndBusinessDetails</Role>
      <ShortName>ORGANIZATION AND BUSINESS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.unitedstatesnaturalgasfund.com/role/DisclosureOrganizationAndBusiness</ParentRole>
      <Position>26</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R27.htm</HtmlFileName>
      <LongName>40201 - Disclosure - SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureSummaryOfSignificantAccountingPoliciesDetails</Role>
      <ShortName>SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.unitedstatesnaturalgasfund.com/role/DisclosureSummaryOfSignificantAccountingPoliciesPolicies</ParentRole>
      <Position>27</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R28.htm</HtmlFileName>
      <LongName>40301 - Disclosure - FEES PAID BY THE FUND AND RELATED PARTY TRANSACTIONS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureFeesPaidByFundAndRelatedPartyTransactionsDetails</Role>
      <ShortName>FEES PAID BY THE FUND AND RELATED PARTY TRANSACTIONS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.unitedstatesnaturalgasfund.com/role/DisclosureFeesPaidByFundAndRelatedPartyTransactions</ParentRole>
      <Position>28</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R29.htm</HtmlFileName>
      <LongName>40401 - Disclosure - CONTRACTS AND AGREEMENTS - Brokerage Commission (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureContractsAndAgreementsBrokerageCommissionDetails</Role>
      <ShortName>CONTRACTS AND AGREEMENTS - Brokerage Commission (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>29</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R30.htm</HtmlFileName>
      <LongName>40402 - Disclosure - CONTRACTS AND AGREEMENTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureContractsAndAgreementsDetails</Role>
      <ShortName>CONTRACTS AND AGREEMENTS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.unitedstatesnaturalgasfund.com/role/DisclosureContractsAndAgreementsTables</ParentRole>
      <Position>30</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R31.htm</HtmlFileName>
      <LongName>40501 - Disclosure - FINANCIAL INSTRUMENTS, OFF-BALANCE SHEET RISKS AND CONTINGENCIES (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureFinancialInstrumentsOffBalanceSheetRisksAndContingenciesDetails</Role>
      <ShortName>FINANCIAL INSTRUMENTS, OFF-BALANCE SHEET RISKS AND CONTINGENCIES (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.unitedstatesnaturalgasfund.com/role/DisclosureFinancialInstrumentsOffBalanceSheetRisksAndContingencies</ParentRole>
      <Position>31</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R32.htm</HtmlFileName>
      <LongName>40601 - Disclosure - FINANCIAL HIGHLIGHTS (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureFinancialHighlightsDetails</Role>
      <ShortName>FINANCIAL HIGHLIGHTS (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.unitedstatesnaturalgasfund.com/role/DisclosureFinancialHighlightsTables</ParentRole>
      <Position>32</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R33.htm</HtmlFileName>
      <LongName>40701 - Disclosure - QUARTERLY FINANCIAL DATA (Unaudited) - Summarized (unaudited) Quarterly Financial Information (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureQuarterlyFinancialDataUnauditedSummarizedUnauditedQuarterlyFinancialInformationDetails</Role>
      <ShortName>QUARTERLY FINANCIAL DATA (Unaudited) - Summarized (unaudited) Quarterly Financial Information (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <ParentRole>http://www.unitedstatesnaturalgasfund.com/role/DisclosureQuarterlyFinancialDataUnauditedTables</ParentRole>
      <Position>33</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R34.htm</HtmlFileName>
      <LongName>40801 - Disclosure - FAIR VALUE OF FINANCIAL INSTRUMENTS - Valuation of UNG's securities using the fair value hierarchy (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureFairValueOfFinancialInstrumentsValuationOfUngSSecuritiesUsingFairValueHierarchyDetails</Role>
      <ShortName>FAIR VALUE OF FINANCIAL INSTRUMENTS - Valuation of UNG's securities using the fair value hierarchy (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>34</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R35.htm</HtmlFileName>
      <LongName>40802 - Disclosure - FAIR VALUE OF FINANCIAL INSTRUMENTS - Fair Value of Derivative Instruments (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureFairValueOfFinancialInstrumentsFairValueOfDerivativeInstrumentsDetails</Role>
      <ShortName>FAIR VALUE OF FINANCIAL INSTRUMENTS - Fair Value of Derivative Instruments (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>35</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R36.htm</HtmlFileName>
      <LongName>40803 - Disclosure - FAIR VALUE OF FINANCIAL INSTRUMENTS - The Effect of Derivative Instruments on the Statements of Operations (Details)</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://www.unitedstatesnaturalgasfund.com/role/DisclosureFairValueOfFinancialInstrumentsEffectOfDerivativeInstrumentsOnStatementsOfOperationsDetails</Role>
      <ShortName>FAIR VALUE OF FINANCIAL INSTRUMENTS - The Effect of Derivative Instruments on the Statements of Operations (Details)</ShortName>
      <MenuCategory>Details</MenuCategory>
      <Position>36</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R37.htm</HtmlFileName>
      <LongName>995410 - Disclosure - Pay vs Performance Disclosure</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/PvpDisclosure</Role>
      <ShortName>Pay vs Performance Disclosure</ShortName>
      <MenuCategory>Uncategorized</MenuCategory>
      <Position>37</Position>
    </Report>
    <Report instance="ung-20231231x10k.htm">
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <HtmlFileName>R38.htm</HtmlFileName>
      <LongName>995445 - Disclosure - Insider Trading Arrangements</LongName>
      <ReportType>Sheet</ReportType>
      <Role>http://xbrl.sec.gov/ecd/role/InsiderTradingArrangements</Role>
      <ShortName>Insider Trading Arrangements</ShortName>
      <MenuCategory>Cover</MenuCategory>
      <Position>38</Position>
    </Report>
    <Report>
      <IsDefault>false</IsDefault>
      <HasEmbeddedReports>false</HasEmbeddedReports>
      <LongName>All Reports</LongName>
      <ReportType>Book</ReportType>
      <ShortName>All Reports</ShortName>
    </Report>
  </MyReports>
  <InputFiles>
    <File>ung-20231231.xsd</File>
    <File>ung-20231231_cal.xml</File>
    <File>ung-20231231_def.xml</File>
    <File>ung-20231231_lab.xml</File>
    <File>ung-20231231_pre.xml</File>
    <File doctype="10-K" isDefinitelyFs="true" isUsgaap="true" original="ung-20231231x10k.htm">ung-20231231x10k.htm</File>
  </InputFiles>
  <SupplementalFiles>
    <File>ung-20231231x10k010.jpg</File>
    <File>ung-20231231x10k011.jpg</File>
    <File>ung-20231231x10k013.jpg</File>
    <File>ung-20231231x10k014.jpg</File>
    <File>ung-20231231x10k017.jpg</File>
    <File>ung-20231231x10k018.jpg</File>
  </SupplementalFiles>
  <BaseTaxonomies>
    <BaseTaxonomy items="265">http://fasb.org/us-gaap/2023</BaseTaxonomy>
    <BaseTaxonomy items="40">http://xbrl.sec.gov/dei/2023</BaseTaxonomy>
    <BaseTaxonomy items="5">http://xbrl.sec.gov/ecd/2023</BaseTaxonomy>
  </BaseTaxonomies>
  <HasPresentationLinkbase>true</HasPresentationLinkbase>
  <HasCalculationLinkbase>true</HasCalculationLinkbase>
</FilingSummary>
