XML 36 R21.htm IDEA: XBRL DOCUMENT
v3.10.0.1

ORGANIZATION AND BUSINESS (Additional Information) (Details) |  | 1 Months Ended |  |  |  |
--- | --- | --- | --- | --- | --- | ---
Jan. 04, 2018 $ / shares shares | Feb. 21, 2012 $ / shares shares | Apr. 30, 2007 | Apr. 18, 2007 USD ($) $ / shares shares | Jun. 30, 2018 $ / shares $ / Unit | Dec. 31, 2017 $ / shares | [1] | Jun. 30, 2017 $ / shares | [1] | Dec. 31, 2016 $ / shares | [1]
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items] |  |  |  |  |  |  |  |
Fee paid by Authorized Purchasers for each order placed to create one or more Creation Baskets or to redeem one or more baskets | $ / Unit |  |  |  |  | 1,000 |  |  |
Number of initially registered units on Form S-1 with the U.S. Securities and Exchange Commission |  |  | 30,000,000 |  |  |  |  |
Net Asset Value Per Unit | $ / shares |  |  |  |  | $ 23.71 | $ 23.34 | $ 27.13 | $ 37.18
Number of units issued | shares |  |  |  | 200,000 |  |  |  |
Value of unit issued | $ |  |  |  | $ 10,001,000 |  |  |  |
Number of registered units |  |  |  |  | 2,080,000,000 |  |  |
Committee For Uniform Securities Identification Procedure Cusip | CUSIP number for UNGs shares changed to 912318300 | CUSIP number for UNGs shares changed to 912318201 |  |  |  |  |  |
Operations Commenced Date |  |  |  | Apr. 18, 2007 |  |  |  |
Prior to Reverse Split [Member] |  |  |  |  |  |  |  |
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items] |  |  |  |  |  |  |  |
Net Asset Value Per Unit | $ / shares | $ 5.69 | $ 5.51 |  | $ 50.00 |  |  |  |
Issued units | shares | 97,466,476 | 174,297,828 |  |  |  |  |  |
Stockholders' Equity, Reverse Stock Split | 1-for-4 reverse share split | 1-for-4 reverse share split |  |  |  |  |  |
Following Reverse Split [Member] |  |  |  |  |  |  |  |
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items] |  |  |  |  |  |  |  |
Net Asset Value Per Unit | $ / shares | $ 22.76 | $ 22.04 |  |  |  |  |  |
Capital Units, Outstanding | shares | 24,366,619 | 43,574,457 |  |  |  |  |  |
Creation Baskets [Member] |  |  |  |  |  |  |  |
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items] |  |  |  |  |  |  |  |
Number of units per basket | $ / Unit |  |  |  |  | 100,000 |  |  |
Redemption Baskets [Member] |  |  |  |  |  |  |  |
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items] |  |  |  |  |  |  |  |
Number of units per basket | $ / Unit |  |  |  |  | 100,000 |  |  |
[1] | On January 4, 2018, there was a 1-for-4 reverse share split. Historical shares outstanding, net asset value per share and market value per share have been adjusted to reflect the 1-for-4 reverse share split on a retroactive basis.

X
- Definition Capital Units, Issued + References No definition available. + Details
Name: | ung_CapitalUnitsIssued
Namespace Prefix: | ung_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Nine character alphanumeric identifier of an entity or issuer and the type of security. + References No definition available. + Details
Name: | ung_CommitteeForUniformSecuritiesIdentificationProcedureCusip
Namespace Prefix: | ung_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fee Paid Per Order + References No definition available. + Details
Name: | ung_FeePaidPerOrder
Namespace Prefix: | ung_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | instant

X
- Definition Net asset value per unit. + References No definition available. + Details
Name: | ung_NetAssetValuePerUnit
Namespace Prefix: | ung_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of Registered Units + References No definition available. + Details
Name: | ung_NumberOfRegisteredUnits
Namespace Prefix: | ung_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of unit per basket. + References No definition available. + Details
Name: | ung_NumberOfUnitPerBasket
Namespace Prefix: | ung_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of Units Registered in Period + References No definition available. + Details
Name: | ung_NumberOfUnitsRegisteredInPeriod
Namespace Prefix: | ung_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Definition Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items] + References No definition available. + Details
Name: | ung_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems
Namespace Prefix: | ung_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Units Issued During Period, Units, New Issues + References No definition available. + Details
Name: | ung_UnitsIssuedDuringPeriodUnitsNewIssues
Namespace Prefix: | ung_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Units Issued During Period, Value, New Issues + References No definition available. + Details
Name: | ung_UnitsIssuedDuringPeriodValueNewIssues
Namespace Prefix: | ung_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Number of capital units or capital shares outstanding. This element is relevant to issuers of face-amount certificates and registered investment companies. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 210 -Section S99 -Paragraph 1 -Subparagraph (SX 210.6-04.16(a)) -URI http://asc.fasb.org/extlink&oid=6488278&loc=d3e603758-122996 + Details
Name: | us-gaap_CapitalUnitsOutstanding
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition Date the operations of the entity commenced, in CCYY-MM-DD format. + References No definition available. + Details
Name: | us-gaap_OperationsCommencedDate1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration

X
- Definition Description of the reverse stock split arrangement. Also provide the retroactive effect given by the reverse split that occurs after the balance sheet date but before the release of financial statements. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SAB Topic 4.C) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187143-122770 + Details
Name: | us-gaap_StockholdersEquityReverseStockSplit
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | invest_InvestmentAxis=ung_PriorToReverseSplitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentAxis=ung_FollowingReverseSplitMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesClassAxis=ung_CreationBasketsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesClassAxis=ung_RedemptionBasketsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |