XML 18 R3.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Condensed Schedule of Investments | Jun. 30, 2018 USD ($)
--- | ---
Value/ Unrealized Gain (Loss) on Open Commodity Contracts | $ (5,130,125) |
Open Futures Contracts - Long [Member] | United States [Member] |  |
Notional Amount | $ 341,477,845 | [1]
Number of Contracts | 20,653 | [1]
Value/ Unrealized Gain (Loss) on Open Commodity Contracts | $ (5,130,125) | [1]
% of Partners' Capital | (1.53%) | [1]
Open Futures Contracts - Long [Member] | United States [Member] | NYMEX Natural Gas Futures NG August 2018 contracts, expiring July 2018 |  |
Notional Amount | $ 250,901,940 |
Number of Contracts | 8,453 |
Value/ Unrealized Gain (Loss) on Open Commodity Contracts | $ (3,736,220) |
% of Partners' Capital | (1.11%) |
Open Futures Contracts - Long [Member] | United States [Member] | ICE Natural Gas Futures LD1 H August 2018 contracts, expiring August 2018 |  |
Notional Amount | $ 90,575,905 |
Number of Contracts | 12,200 |
Value/ Unrealized Gain (Loss) on Open Commodity Contracts | $ (1,393,905) |
% of Partners' Capital | (0.42%) |
Cash Equivalents [Member] |  |
Market Value | $ 311,184,062 |
% of Partners' Capital | 92.52% |
Cash Equivalents [Member] | United States Treasury Obligations [Member] |  |
Market Value | $ 253,184,062 |
% of Partners' Capital | 75.28% |
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills 1.56%, 7/05/2018 [Member] |  |
Principal Amount | $ 10,000,000 |
Market Value | $ 9,998,278 |
% of Partners' Capital | 2.97% |
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills 1.56%, 7/12/2018 [Member] |  |
Principal Amount | $ 10,000,000 |
Market Value | $ 9,995,264 |
% of Partners' Capital | 2.97% |
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills 1.77%, 8/16/2018 [Member] |  |
Principal Amount | $ 5,000,000 |
Market Value | $ 4,988,787 |
% of Partners' Capital | 1.48% |
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills 1.82%, 8/23/2018 [Member] |  |
Principal Amount | $ 5,000,000 |
Market Value | $ 4,986,750 |
% of Partners' Capital | 1.48% |
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills 1.85%, 9/06/2018 [Member] |  |
Principal Amount | $ 5,000,000 |
Market Value | $ 4,982,971 |
% of Partners' Capital | 1.48% |
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills 1.90%, 9/27/2018 [Member] |  |
Principal Amount | $ 10,000,000 |
Market Value | $ 9,954,106 |
% of Partners' Capital | 2.96% |
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills 1.90%, 10/11/2018 [Member] |  |
Principal Amount | $ 25,000,000 |
Market Value | $ 24,866,833 |
% of Partners' Capital | 7.40% |
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills 1.97%, 10/18/2018 [Member] |  |
Principal Amount | $ 5,000,000 |
Market Value | $ 4,970,479 |
% of Partners' Capital | 1.48% |
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills 2.00%, 10/25/2018 [Member] |  |
Principal Amount | $ 10,000,000 |
Market Value | $ 9,936,200 |
% of Partners' Capital | 2.96% |
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills 2.00%, 11/01/2018 [Member] |  |
Principal Amount | $ 10,000,000 |
Market Value | $ 9,932,350 |
% of Partners' Capital | 2.95% |
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills 2.03%, 11/08/2018 [Member] |  |
Principal Amount | $ 20,000,000 |
Market Value | $ 19,855,194 |
% of Partners' Capital | 5.90% |
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills 2.05%, 11/15/2018 [Member] |  |
Principal Amount | $ 15,000,000 |
Market Value | $ 14,884,121 |
% of Partners' Capital | 4.43% |
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills 2.07%, 11/23/2018 [Member] |  |
Principal Amount | $ 15,000,000 |
Market Value | $ 14,876,146 |
% of Partners' Capital | 4.42% |
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills 2.05%, 11/29/2018 [Member] |  |
Principal Amount | $ 15,000,000 |
Market Value | $ 14,872,594 |
% of Partners' Capital | 4.42% |
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills 2.09%, 12/06/2018 [Member] |  |
Principal Amount | $ 20,000,000 |
Market Value | $ 19,818,300 |
% of Partners' Capital | 5.89% |
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills 2.06%, 12/13/2018 [Member] |  |
Principal Amount | $ 25,000,000 |
Market Value | $ 24,766,250 |
% of Partners' Capital | 7.37% |
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills 2.09%, 12/20/2018 [Member] |  |
Principal Amount | $ 30,000,000 |
Market Value | $ 29,703,300 |
% of Partners' Capital | 8.83% |
Cash Equivalents [Member] | United States Treasury Obligations [Member] | U.S. Treasury Bills 2.07%, 12/27/2018 [Member] |  |
Principal Amount | $ 20,000,000 |
Market Value | $ 19,796,139 |
% of Partners' Capital | 5.89% |
Cash Equivalents [Member] | United States [Member] | Money Market Funds [Member] |  |
Market Value | $ 58,000,000 |
% of Partners' Capital | 17.24% |
Cash Equivalents [Member] | United States [Member] | Money Market Funds [Member] | Fidelity Investments Money Market Funds - Government Portfolio [Member] |  |
Principal Amount | $ 3,000,000 |
Market Value | $ 3,000,000 |
% of Partners' Capital | 0.89% |
Cash Equivalents [Member] | United States [Member] | Money Market Funds [Member] | Goldman Sachs Financial Square Funds - Government Fund - Class FS [Member] |  |
Principal Amount | $ 50,000,000 |
Market Value | $ 50,000,000 |
% of Partners' Capital | 14.86% |
Cash Equivalents [Member] | United States [Member] | Money Market Funds [Member] | Morgan Stanley Institutional Liquidity Funds - Government Portfolio [Member] |  |
Principal Amount | $ 5,000,000 |
Market Value | $ 5,000,000 |
% of Partners' Capital | 1.49% |
[1] | Collateral amounted to $30,787,364 on open futures contracts.

X
- Definition Percentage of Partners Capital + References No definition available. + Details
Name: | ung_PercentageOfPartnersCapital
Namespace Prefix: | ung_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Unrealized gain (loss) on open commodity futures and cleared swap contracts. + References No definition available. + Details
Name: | ung_UnrealizedGainLossOnOpenCommodityFuturesAndClearedSwapContracts
Namespace Prefix: | ung_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Value of the investment at close of period. For schedules of investments that are categorized, the value would be aggregated by category. For investment in and advances to affiliates, if operations of any controlled companies are different in character from those of the company, group such affiliates within divisions and by type of activities. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 210 -Section 50 -Paragraph 6 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=99383244&loc=d3e12121-115841 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-12C.Column C.7) -URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611225-123010 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 6 -Subparagraph (SX 210.12-14.Column E.2,3) -URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611322-123010 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-12.Column C.3,4) -URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611133-123010 Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 5 -Subparagraph (SX 210.12-13.Column C.6) -URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611282-123010 + Details
Name: | us-gaap_InvestmentOwnedAtFairValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Balance held at close of period in number of contracts. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 6 -Subparagraph (SX 210.12-14.Column B) -URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611322-123010 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-12C.Column B) -URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611225-123010 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-12.Column B) -URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611133-123010 + Details
Name: | us-gaap_InvestmentOwnedBalanceContracts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition For investments which are quantified by principal amount, the principle balance held at close of period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 210 -Section 50 -Paragraph 6 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=99383244&loc=d3e12121-115841 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-12C.Column B) -URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611225-123010 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 6 -Subparagraph (SX 210.12-14.Column B) -URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611322-123010 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-12.Column B) -URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611133-123010 + Details
Name: | us-gaap_InvestmentOwnedBalancePrincipalAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Nominal or face amount on the investment owned. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 20 -Section 10 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6438156&loc=d3e57880-113973 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 10 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6431724&loc=d3e32938-113948 + Details
Name: | us-gaap_InvestmentOwnedUnderlyingFaceAmountAtMarketValue
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Details
Name: | us-gaap_InvestmentTypeAxis=ung_OpenFuturesContractsLongMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_NymexNaturalGasFuturesNgMay2018ContractsExpiringMay2018Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=ung_IceNaturalGasFuturesLd1HMay2018ContractsExpiringMay2018Member
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_InvestmentSecuritiesClassAxis=us-gaap_USTreasurySecuritiesMember
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: |

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

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

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

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

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

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

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

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

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

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