XML 19 R4.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Condensed Schedule of Investments (Parenthetical) | 9 Months Ended
--- | ---
Sep. 30, 2017 USD ($)
Debt Instrument, Collateral Amount | $ 88,881,582
United States [Member] | US Treasury Bill Securities One [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 0.90%
Expiration date | 10/05/2017
United States [Member] | US Treasury Bill Securities Two [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 0.92%
Expiration date | 10/12/2017
United States [Member] | US Treasury Bill Securities Three [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 0.91%
Expiration date | 10/19/2017
United States [Member] | US Treasury Bill Securities Four [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 0.95%
Expiration date | 10/26/2017
United States [Member] | US Treasury Bill Securities Five [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 0.97%
Expiration date | 11/02/2017
United States [Member] | US Treasury Bill Securities Six [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 1.01%
Expiration date | 11/09/2017
United States [Member] | US Treasury Bill Securities Seven [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 0.98%
Expiration date | 11/16/2017
United States [Member] | US Treasury Bill Securities Eight [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 1.05%
Expiration date | 11/24/2017
United States [Member] | US Treasury Bill Securities Nine [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 1.05%
Expiration date | 11/30/2017
United States [Member] | US Treasury Bill Securities Ten [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 1.08%
Expiration date | 12/07/2017
United States [Member] | US Treasury Bill Securities Eleven [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 1.09%
Expiration date | 12/14/2017
United States [Member] | US Treasury Bill Securities Twelve Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 1.11%
Expiration date | 12/21/2017
United States [Member] | US Treasury Bill Securities Thirteen [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 1.10%
Expiration date | 12/28/2017
United States [Member] | US Treasury Bill Securities Fourteen [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 1.12%
Expiration date | 1/04/2018
United States [Member] | US Treasury Bill Securities Fifteen [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 1.11%
Expiration date | 1/11/2018
United States [Member] | US Treasury Bill Securities Sixteen [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 1.10%
Expiration date | 1/18/2018
United States [Member] | US Treasury Bill Securities Seventeen [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 1.12%
Expiration date | 1/25/2018
United States [Member] | US Treasury Bill Securities Eighteen [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 1.12%
Expiration date | 2/01/2018
United States [Member] | US Treasury Bill Securities Nineteen [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 1.13%
Expiration date | 2/08/2018
United States [Member] | US Treasury Bill Securities Twenty [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 1.12%
Expiration date | 2/15/2018
United States [Member] | US Treasury Bill Securities Twenty One [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 1.10%
Expiration date | 2/22/2018
United States [Member] | US Treasury Bill Securities Twenty Two [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 1.09%
Expiration date | 3/01/2018
United States [Member] | US Treasury Bill Securities Twenty Three [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 1.14%
Expiration date | 3/08/2018
United States [Member] | US Treasury Bill Securities Twenty Four [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 1.14%
Expiration date | 3/15/2018
United States [Member] | US Treasury Bill Securities Twenty Five [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 1.16%
Expiration date | 3/22/2018
United States [Member] | US Treasury Bill Securities Twenty Six [Member] | US Treasury Securities [Member] | Cash Equivalents [Member] |
Interest rate | 1.17%
Expiration date | 3/29/2018

X
- Definition Amount of assets pledged to secure a debt instrument. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 470 -Section 50 -Paragraph 3 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823 + Details
Name: | us-gaap_DebtInstrumentCollateralAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The list of dates or date range within which the options may be exercised of the investment subject to option. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 6 -Subparagraph (SX 210.12-14.4(b)) -URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611322-123010 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 5 -Subparagraph (SX 210.12-13.5(d)) -URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611282-123010 + Details
Name: | us-gaap_InvestmentOwnedSubjectToOptionExerciseDates
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | invest_InvestmentGeographicRegionAxis=country_US
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsFourMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsFiveMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsSixMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsSevenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillEightMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsNineMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsTenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsElevenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsTwelveMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsThirteenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillFourteenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsFifteenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsSixteenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsSeventeenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsEighteenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsNineteenMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsTwentyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsTwentyOneMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsTwentyTwoMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsTwentyThreeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsTwentyFourMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsTwentyFiveMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_UsTreasuryBillsTwentySixMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |