Name:	ung_AverageDailyPercentageChangeInPriceOfBenchmarkFuturesContractConsidered
Namespace Prefix:	ung_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

Capital Units, Issued

No definition available.

Name:	ung_CapitalUnitsIssued
Namespace Prefix:	ung_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Nine character alphanumeric identifier of an entity or issuer and the type of security.

No definition available.

Name:	ung_CommitteeForUniformSecuritiesIdentificationProcedureCusip
Namespace Prefix:	ung_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The amount of fee paid per order.

No definition available.

Name:	ung_FeePaidPerOrder
Namespace Prefix:	ung_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Per unit of net asset value.

No definition available.

Name:	ung_NetAssetValuePerUnit
Namespace Prefix:	ung_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	instant

Number of successive valuation days over which the average daily percentage change in the fund's NAV will be considered for achieving the entity's investment objective, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	ung_NumberOfSuccessiveValuationDays
Namespace Prefix:	ung_
Data Type:	xbrli:durationItemType
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Period Type:	duration

Number of units per Basket.

No definition available.

Name:	ung_NumberOfUnitsPerBasket
Namespace Prefix:	ung_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Number of initially registered shares.

No definition available.

Name:	ung_NumberOfUnitsRegisteredInPeriod
Namespace Prefix:	ung_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Organization, Consolidation and Presentation of Financial Statements Disclosure

No definition available.

Name:	ung_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems
Namespace Prefix:	ung_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Number of shares issued during the period.

No definition available.

Name:	ung_UnitsIssuedDuringPeriodUnitsNewIssues
Namespace Prefix:	ung_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Amount received from the issuance of new shares during the period.

No definition available.

Name:	ung_UnitsIssuedDuringPeriodValueNewIssues
Namespace Prefix:	ung_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Number of capital units or capital shares outstanding. This element is relevant to issuers of face-amount certificates and registered investment companies.

No definition available.

Name:	us-gaap_CapitalUnitsOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

Balance held at close of period in number of contracts.

No definition available.

Name:	us-gaap_InvestmentOwnedBalanceContracts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:decimalItemType
Balance Type:	na
Period Type:	instant

Ratio applied to the conversion of stock split, for example but not limited to, one share converted to two or two shares converted to one.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Topic 505
-SubTopic 10
-Name Accounting Standards Codification
-Section S99
-Paragraph 4
-Subparagraph (SAB Topic 4.C)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480008/505-10-S99-4

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Data Type:	xbrli:pureItemType
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Period Type:	duration

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_ConversionOfStockByUniqueDescriptionAxis=ung_FollowingReverseSplitMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	srt_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=ung_NymexNaturalGasFuturesNgAugust2023ContractsExpiringJanuary2023Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_CashAndCashEquivalentsAxis=ung_CreationBasketsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: