2.4.0.6 Html 110 167 1 true 63 0 false 9 false false R1.htm 001 - Document - Document and Entity Information Sheet http://www.unitedstatesnaturalgasfund.com/role/DocumentDocumentandEntityInformation Document and Entity Information false false R2.htm 002 - Statement - Condensed Statements of Financial Condition Sheet http://www.unitedstatesnaturalgasfund.com/role/StatementOfFinancialPositionUnclassified-SecuritiesBasedOperations Condensed Statements of Financial Condition false false R3.htm 003 - Statement - Condensed Schedule of Investments Sheet http://www.unitedstatesnaturalgasfund.com/role/CondensedScheduleOfInvestments Condensed Schedule of Investments false false R4.htm 004 - Statement - Condensed Schedule of Investments (Parenthetical) Sheet http://www.unitedstatesnaturalgasfund.com/role/CondensedScheduleOfInvestmentsParenthetical Condensed Schedule of Investments (Parenthetical) false false R5.htm 005 - Statement - Condensed Statements of Operations Sheet http://www.unitedstatesnaturalgasfund.com/role/CondensedStatementsOfOperations Condensed Statements of Operations false false R6.htm 006 - Statement - Condensed Statements of Changes in Partners' Capital Sheet http://www.unitedstatesnaturalgasfund.com/role/CondensedStatementsOfChangesInPartnersCapital Condensed Statements of Changes in Partners' Capital false false R7.htm 007 - Statement - Statements of Changes in Partners' Capital Sheet http://www.unitedstatesnaturalgasfund.com/role/StatementsOfChangesInPartnersCapital Statements of Changes in Partners' Capital false false R8.htm 008 - Statement - Condensed Statements of Cash Flows Sheet http://www.unitedstatesnaturalgasfund.com/role/CondensedStatementsOfCashFlows Condensed Statements of Cash Flows false false R9.htm 009 - Schedule - Schedule of Investments Sheet http://www.unitedstatesnaturalgasfund.com/role/NotesToFinancialStatementsSummaryOfInvestmentHoldingsScheduleOfInvestmentsTextBlock Schedule of Investments false false R10.htm 010 - Disclosure - Organization and Business Sheet http://www.unitedstatesnaturalgasfund.com/role/NotesToFinancialStatementsOrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureTextBlock Organization and Business false false R11.htm 011 - Disclosure - Summary of Significant Accounting Policies Sheet http://www.unitedstatesnaturalgasfund.com/role/NotesToFinancialStatementsSignificantAccountingPoliciesTextBlock Summary of Significant Accounting Policies false false R12.htm 012 - Disclosure - Fees Paid by the Fund and Related Party Transactions Sheet http://www.unitedstatesnaturalgasfund.com/role/NotesToFinancialStatementsFeesPaidAndRelatedPartyTransactionsDisclosureTextBlock Fees Paid by the Fund and Related Party Transactions false false R13.htm 013 - Disclosure - Contracts and Agreements Sheet http://www.unitedstatesnaturalgasfund.com/role/NotesToFinancialStatementsLongTermContractsOrProgramsDisclosureTextBlock Contracts and Agreements true false R14.htm 014 - Disclosure - Financial Instruments, Off-Balance Sheet Risks and Contingencies Sheet http://www.unitedstatesnaturalgasfund.com/role/NotesToFinancialStatementsDisclosureOfFairValueOffBalanceSheetRisksTextBlock Financial Instruments, Off-Balance Sheet Risks and Contingencies false false R15.htm 015 - Disclosure - Financial Highlights Sheet http://www.unitedstatesnaturalgasfund.com/role/NotesToFinancialStatementsSupplementalFinancialInformationDisclosureTextBlock Financial Highlights false false R16.htm 016 - Disclosure - Fair Value Of Financial Instruments Sheet http://www.unitedstatesnaturalgasfund.com/role/NotesToFinancialStatementsFairValueDisclosuresTextBlock Fair Value Of Financial Instruments false false R17.htm 017 - Disclosure - Offsetting Assets and Liabilities Sheet http://www.unitedstatesnaturalgasfund.com/role/NotesToFinancialStatementsDescriptionOfNewAccountingPronouncementsTextBlock Offsetting Assets and Liabilities false false R18.htm 018 - Disclosure - Subsequent Events Sheet http://www.unitedstatesnaturalgasfund.com/role/NotesToFinancialStatementsSubsequentEventsTextBlock Subsequent Events false false R19.htm 019 - Disclosure - Summary of Significant Accounting Policies (Policies) Sheet http://www.unitedstatesnaturalgasfund.com/role/NotesToFinancialStatementsSignificantAccountingPoliciesTextBlockPolicies Summary of Significant Accounting Policies (Policies) false false R20.htm 020 - Disclosure - Financial Highlights (Tables) Sheet http://www.unitedstatesnaturalgasfund.com/role/NotesToFinancialStatementsSupplementalFinancialInformationDisclosureTextBlockTables Financial Highlights (Tables) false false R21.htm 021 - Disclosure - Fair Value Of Financial Instruments (Tables) Sheet http://www.unitedstatesnaturalgasfund.com/role/NotesToFinancialStatementsFairValueDisclosuresTextBlockTables Fair Value Of Financial Instruments (Tables) false false R22.htm 022 - Disclosure - Offsetting Assets And Liabilities (Tables) Sheet http://www.unitedstatesnaturalgasfund.com/role/OffsettingAssetsAndLiabilitiesTables Offsetting Assets And Liabilities (Tables) false false R23.htm 023 - Disclosure - Organization and Business (Additional Information) (Details) Sheet http://www.unitedstatesnaturalgasfund.com/role/DisclosureOrganizationAndBusinessAdditionalInformation Organization and Business (Additional Information) (Details) false false R24.htm 024 - Disclosure - Summary of Significant Accounting Policies (Additional Information) (Details) Sheet http://www.unitedstatesnaturalgasfund.com/role/DisclosureSummaryOfSignificantAccountingPoliciesAdditionalInformation Summary of Significant Accounting Policies (Additional Information) (Details) false false R25.htm 025 - Disclosure - Fees Paid by Fund and Related Party Transactions (Additional Information) (Details) Sheet http://www.unitedstatesnaturalgasfund.com/role/DisclosureFeesPaidByFundAndRelatedPartyTransactionsAdditionalInformation Fees Paid by Fund and Related Party Transactions (Additional Information) (Details) false false R26.htm 026 - Disclosure - Contracts and Agreements (Additional Information) (Details) Sheet http://www.unitedstatesnaturalgasfund.com/role/DisclosureContractsAndAgreementsAdditionalInformation Contracts and Agreements (Additional Information) (Details) false false R27.htm 027 - Disclosure - Financial Instruments, Off-Balance Sheet Risks and Contingencies (Additional Information) (Details) Sheet http://www.unitedstatesnaturalgasfund.com/role/DisclosureFinancialInstrumentsOffBalanceSheetRisksAndContingenciesAdditionalInformation Financial Instruments, Off-Balance Sheet Risks and Contingencies (Additional Information) (Details) false false R28.htm 028 - Disclosure - Financial Highlights (Per Unit Performance Data and Other Supplemental Financial Data) (Details) Sheet http://www.unitedstatesnaturalgasfund.com/role/DisclosurePerUnitPerformanceDataAndOtherSupplementalFinancialData Financial Highlights (Per Unit Performance Data and Other Supplemental Financial Data) (Details) false false R29.htm 029 - Disclosure - Fair Value Of Financial Instruments (Valuation of Securities Using Fair Value Hierarchy) (Details) Sheet http://www.unitedstatesnaturalgasfund.com/role/DisclosureValuationOfSecuritiesUsingFairValueHierarchy Fair Value Of Financial Instruments (Valuation of Securities Using Fair Value Hierarchy) (Details) false false R30.htm 030 - Disclosure - Fair Value Of Financial Instruments (Reconciliation of Assets in which Significant Observable Inputs (Level III) were used in Determining Fair Value) (Details) Sheet http://www.unitedstatesnaturalgasfund.com/role/DisclosureReconciliationOfAssetsInWhichSignificantObservableInputsLevelIIIWereUsedInDeterminingFairValue Fair Value Of Financial Instruments (Reconciliation of Assets in which Significant Observable Inputs (Level III) were used in Determining Fair Value) (Details) false false R31.htm 031 - Disclosure - Fair Value Of Financial Instruments (Reconciliation of Assets in which Significant Observable Inputs (Level III) were used in Determining Fair Value) (Parenthetical) (Details) Sheet http://www.unitedstatesnaturalgasfund.com/role/DisclosureReconciliationOfAssetsInWhichSignificantObservableInputsLevelIIIWereUsedInDeterminingFairValueParenthetical Fair Value Of Financial Instruments (Reconciliation of Assets in which Significant Observable Inputs (Level III) were used in Determining Fair Value) (Parenthetical) (Details) false false R32.htm 032 - Disclosure - Fair Value Of Financial Instruments (Fair Value of Derivative Instruments) (Details) Sheet http://www.unitedstatesnaturalgasfund.com/role/DisclosureFairValueOfDerivativeInstruments Fair Value Of Financial Instruments (Fair Value of Derivative Instruments) (Details) false false R33.htm 033 - Disclosure - Fair Value Of Financial Instruments (Effect of Derivative Instruments on Condensed Statements of Operations) (Details) Sheet http://www.unitedstatesnaturalgasfund.com/role/DisclosureEffectOfDerivativeInstrumentsOnCondensedStatementsOfOperations Fair Value Of Financial Instruments (Effect of Derivative Instruments on Condensed Statements of Operations) (Details) false false R34.htm 034 - Disclosure - Offsetting Assets And Liabilities (Offsetting of Financial Assets and Derivative Assets) (Details) Sheet http://www.unitedstatesnaturalgasfund.com/role/OffsettingAssetsAndLiabilitiesOffsettingOfFinancialAssetsAndDerivativeAssetsDeatils Offsetting Assets And Liabilities (Offsetting of Financial Assets and Derivative Assets) (Details) false false R35.htm 035 - Disclosure - Offsetting Assets And Liabilities (Financial Assets, Derivative Assets, and Collateral Held by Counterparty) (Details) Sheet http://www.unitedstatesnaturalgasfund.com/role/OffsettingAssetsAndLiabilitiesFinancialAssetsDerivativeAssetsAndCollateralHeldByCounterpartyDetails Offsetting Assets And Liabilities (Financial Assets, Derivative Assets, and Collateral Held by Counterparty) (Details) false false R36.htm 036 - Disclosure - Offsetting Assets And Liabilities (Offsetting of Financial Liabilities and Derivative Liabilities) (Details) Sheet http://www.unitedstatesnaturalgasfund.com/role/OffsettingAssetsAndLiabilitiesOffsettingOfFinancialLiabilitiesAndDerivativeLiabilitiesDetails Offsetting Assets And Liabilities (Offsetting of Financial Liabilities and Derivative Liabilities) (Details) false false R37.htm 037 - Disclosure - Offsetting Assets And Liabilities (Financial Liabilities, Derivative Liabilities, and Collateral Pledged by Counterparty) (Details) Sheet http://www.unitedstatesnaturalgasfund.com/role/OffsettingAssetsAndLiabilitiesFinancialLiabilitiesDerivativeLiabilitiesAndCollateralPledgedByCounterpartyDetails Offsetting Assets And Liabilities (Financial Liabilities, Derivative Liabilities, and Collateral Pledged by Counterparty) (Details) false false All Reports Book All Reports Element ung_BaseFeePercentage had a mix of decimals attribute values: 4 5 6. Element us-gaap_NetIncomeLoss had a mix of decimals attribute values: -3 0. Element us-gaap_PartnersCapital had a mix of decimals attribute values: -3 0. Element us-gaap_PartnersCapitalAccountContributions had a mix of decimals attribute values: -3 0. Element us-gaap_PartnersCapitalAccountRedemptions had a mix of decimals attribute values: -3 0. Process Flow-Through: 002 - Statement - Condensed Statements of Financial Condition Process Flow-Through: Removing column 'Mar. 31, 2012' Process Flow-Through: Removing column 'Dec. 31, 2011' Process Flow-Through: Removing column 'Apr. 18, 2007' Process Flow-Through: 003 - Statement - Condensed Schedule of Investments Process Flow-Through: Removing column 'Mar. 31, 2013' Process Flow-Through: Removing column 'Dec. 31, 2012' Process Flow-Through: Removing column 'Mar. 31, 2013 Open Cleared Swap and Futures Contracts [Member] Contracts' Process Flow-Through: 004 - Statement - Condensed Schedule of Investments (Parenthetical) Process Flow-Through: 005 - Statement - Condensed Statements of Operations Process Flow-Through: 007 - Statement - Statements of Changes in Partners' Capital Process Flow-Through: 008 - Statement - Condensed Statements of Cash Flows ung-20130331.xml ung-20130331.xsd ung-20130331_cal.xml ung-20130331_def.xml ung-20130331_lab.xml ung-20130331_pre.xml true true