XML 19 R4.htm IDEA: XBRL DOCUMENT
v3.7.0.1

Schedule of Investments (Parenthetical) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2016 | Dec. 31, 2015
Collateral Amount On Open Futures Contracts | $ 6,997,275 | $ 29,320,958
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.13%, 1/21/2016 |  |
Interest rate |  | 0.13%
Expiration date |  | 1/21/2016
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.15%, 1/28/2016 |  |
Interest rate |  | 0.15%
Expiration date |  | 1/28/2016
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.19%, 2/04/2016 |  |
Interest rate |  | 0.19%
Expiration date |  | 2/04/2016
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.22%, 2/11/2016 |  |
Interest rate |  | 0.22%
Expiration date |  | 2/11/2016
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.20%, 2/18/2016 |  |
Interest rate |  | 0.20%
Expiration date |  | 2/18/2016
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.20%, 2/25/2016 |  |
Interest rate |  | 0.20%
Expiration date |  | 2/25/2016
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.23%, 3/03/2016 |  |
Interest rate |  | 0.23%
Expiration date |  | 3/03/2016
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.26%, 3/10/2016 |  |
Interest rate |  | 0.26%
Expiration date |  | 3/10/2016
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.24%, 3/17/2016 |  |
Interest rate |  | 0.24%
Expiration date |  | 3/17/2016
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.09%, 3/24/2016 |  |
Interest rate |  | 0.09%
Expiration date |  | 3/24/2016
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.07%, 3/31/2016 |  |
Interest rate |  | 0.07%
Expiration date |  | 3/31/2016
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.07%, 4/07/2016 |  |
Interest rate |  | 0.07%
Expiration date |  | 4/07/2016
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.07%, 4/14/2016 |  |
Interest rate |  | 0.07%
Expiration date |  | 4/14/2016
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.11%, 4/21/2016 |  |
Interest rate |  | 0.11%
Expiration date |  | 4/21/2016
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.21%, 4/28/2016 |  |
Interest rate |  | 0.21%
Expiration date |  | 4/28/2016
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.26%, 5/05/2016 |  |
Interest rate |  | 0.26%
Expiration date |  | 5/05/2016
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.33%, 5/12/2016 |  |
Interest rate |  | 0.33%
Expiration date |  | 5/12/2016
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.31%, 5/19/2016 |  |
Interest rate |  | 0.31%
Expiration date |  | 5/19/2016
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.35%, 5/26/2016 |  |
Interest rate |  | 0.35%
Expiration date |  | 5/26/2016
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.43%, 6/02/2016 |  |
Interest rate |  | 0.43%
Expiration date |  | 6/02/2016
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.52%, 6/09/2016 |  |
Interest rate |  | 0.52%
Expiration date |  | 6/09/2016
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.48%, 6/16/2016 |  |
Interest rate |  | 0.48%
Expiration date |  | 6/16/2016
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.46%, 6/23/2016 |  |
Interest rate |  | 0.46%
Expiration date |  | 6/23/2016
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.47%, 6/30/2016 |  |
Interest rate |  | 0.47%
Expiration date |  | 6/30/2016
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.34%, 1/05/2017 |  |
Interest rate | 0.34% |
Expiration date | 1/05/2017 |
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.43%, 1/19/2017 |  |
Interest rate | 0.43% |
Expiration date | 1/19/2017 |
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.36%, 1/26/2017 |  |
Interest rate | 0.36% |
Expiration date | 1/26/2017 |
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.40%, 2/02/2017 |  |
Interest rate | 0.40% |
Expiration date | 2/02/2017 |
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.42%, 2/09/2017 |  |
Interest rate | 0.42% |
Expiration date | 2/09/2017 |
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.45%, 2/16/2017 |  |
Interest rate | 0.45% |
Expiration date | 2/16/2017 |
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.45%, 2/23/2017 |  |
Interest rate | 0.45% |
Expiration date | 2/23/2017 |
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.45%, 3/02/2017 |  |
Interest rate | 0.45% |
Expiration date | 3/02/2017 |
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.47%, 3/09/2017 |  |
Interest rate | 0.47% |
Expiration date | 3/09/2017 |
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.50%, 3/16/2017 |  |
Interest rate | 0.50% |
Expiration date | 3/16/2017 |
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.45%, 3/23/2017 |  |
Interest rate | 0.45% |
Expiration date | 3/23/2017 |
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.43%, 3/30/2017 |  |
Interest rate | 0.43% |
Expiration date | 3/30/2017 |
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.46%, 4/06/2017 |  |
Interest rate | 0.46% |
Expiration date | 4/06/2017 |
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.47%, 4/13/2017 |  |
Interest rate | 0.47% |
Expiration date | 4/13/2017 |
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.46%, 4/20/2017 |  |
Interest rate | 0.46% |
Expiration date | 4/20/2017 |
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.47%, 4/27/2017 |  |
Interest rate | 0.47% |
Expiration date | 4/27/2017 |
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.49%, 5/04/2017 |  |
Interest rate | 0.49% |
Expiration date | 5/04/2017 |
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.55%, 5/11/2017 |  |
Interest rate | 0.55% |
Expiration date | 5/11/2017 |
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.60%, 5/18/2017 |  |
Interest rate | 0.60% |
Expiration date | 5/18/2017 |
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.61%, 5/25/2017 |  |
Interest rate | 0.61% |
Expiration date | 5/25/2017 |
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.60%, 6/01/2017 |  |
Interest rate | 0.60% |
Expiration date | 6/01/2017 |
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.62%, 6/08/2017 |  |
Interest rate | 0.62% |
Expiration date | 6/08/2017 |
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.65%, 6/15/2017 |  |
Interest rate | 0.65% |
Expiration date | 6/15/2017 |
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.64%, 6/22/2017 |  |
Interest rate | 0.64% |
Expiration date | 6/22/2017 |
US Treasury Securities | Cash Equivalents | U.S.Treasury Bills 0.60%, 6/29/2017 |  |
Interest rate | 0.60% |
Expiration date | 6/29/2017 |
NYMEX WTI Crude Oil Futures CL August 2017 contracts, expiring July 2017 |  |
Expiration date | July 2017 |
NYMEX WTI Crude Oil Futures CL September 2017 contracts, expiring August 2017 |  |
Expiration date | August 2017 |
NYMEX WTI Crude Oil Futures CL October 2017 contracts, expiring September 2017 |  |
Expiration date | September 2017 |
NYMEX WTI Crude Oil Futures CL November 2017 contracts, expiring October 2017 |  |
Expiration date | October 2017 |
NYMEX WTI Crude Oil Futures CL December 2017 contracts, expiring November 2017 |  |
Expiration date | November 2017 |
NYMEX WTI Crude Oil Futures CL January 2018 contracts, expiring December 2017 |  |
Expiration date | December 2017 |
United States | NYMEX WTI Crude Oil Futures CL February 2017 contracts, expiring January 2017 | Open Futures Contracts, Long |  |
Expiration date | January 2017 |
United States | NYMEX WTI Crude Oil Futures CL March 2017 contracts, expiring February 2017 | Open Futures Contracts, Long |  |
Expiration date | February 2017 |
United States | NYMEX WTI Crude Oil Futures CL April 2017 contracts, expiring March 2017 | Open Futures Contracts, Long |  |
Expiration date | March 2017 |
United States | NYMEX WTI Crude Oil Futures CL May 2017 contracts, expiring April 2017 | Open Futures Contracts, Long |  |
Expiration date | April 2017 |
United States | NYMEX WTI Crude Oil Futures CL June 2017 contracts, expiring May 2017 | Open Futures Contracts, Long |  |
Expiration date | May 2017 |
United States | NYMEX WTI Crude Oil Futures CL July 2017 contracts, expiring June 2017 | Open Futures Contracts, Long |  |
Expiration date | June 2017 |
United States | NYMEX WTI Crude Oil Futures CL August 2017 contracts, expiring July 2017 | Open Futures Contracts, Long |  |
Expiration date |  | July 2016
United States | NYMEX WTI Crude Oil Futures CL September 2017 contracts, expiring August 2017 | Open Futures Contracts, Long |  |
Expiration date |  | August 2016
United States | NYMEX WTI Crude Oil Futures CL October 2017 contracts, expiring September 2017 | Open Futures Contracts, Long |  |
Expiration date |  | September 2016
United States | NYMEX WTI Crude Oil Futures CL November 2017 contracts, expiring October 2017 | Open Futures Contracts, Long |  |
Expiration date |  | October 2016
United States | NYMEX WTI Crude Oil Futures CL December 2017 contracts, expiring November 2017 | Open Futures Contracts, Long |  |
Expiration date |  | November 2016
United States | NYMEX WTI Crude Oil Futures CL January 2018 contracts, expiring December 2017 | Open Futures Contracts, Long |  |
Expiration date |  | December 2016
United States | NYMEX WTI Crude Oil Futures CL February 2016 contracts, expiring January 2016 | Open Futures Contracts, Long |  |
Expiration date |  | January 2016
United States | NYMEX WTI Crude Oil Futures CL March 2016 contracts, expiring February 2016 | Open Futures Contracts, Long |  |
Expiration date |  | February 2016
United States | NYMEX WTI Crude Oil Futures CL April 2016 contracts, expiring March 2016 | Open Futures Contracts, Long |  |
Expiration date |  | March 2016
United States | NYMEX WTI Crude Oil Futures CL May 2016 contracts, expiring April 2016 | Open Futures Contracts, Long |  |
Expiration date |  | April 2016
United States | NYMEX WTI Crude Oil Futures CL June 2016 contracts, expiring May 2016 | Open Futures Contracts, Long |  |
Expiration date |  | May 2016
United States | NYMEX WTI Crude Oil Futures CL July 2016 contracts, expiring June 2016 | Open Futures Contracts, Long |  |
Expiration date |  | June 2016

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
- Definition The collateral amount on open future contracts. + References No definition available. + Details
Name: | usl_CollateralAmountOnOpenFuturesContracts
Namespace Prefix: | usl_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0464062017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0474132017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0464202017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0474272017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0495042017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0555112017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0605182017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0615252017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0606012017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0626082017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0656152017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0646222017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0606292017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0131212016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0151282016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0192042016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0222112016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0202182016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0202252016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0263102016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0243172016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0093242016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0073312016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0074072016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_Ustreasurybillssecurities37memberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_Ustreasurybillssecurities38membermemberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_Ustreasurybillssecurities39membermemberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_UsTreasuryBills0335122016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_Ustreasurybillssecurities42memberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_Ustreasurybillssecurities43memberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_Ustreasurybillssecurities44memberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_Ustreasurybillssecurities45memberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_Ustreasurybillssecurities46memberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_Ustreasurybillssecurities47memberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_Ustreasurybillssecurities48memberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_Ustreasurybillssecurities49memberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_Ustreasurybillssecurities50memberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_Ustreasurybillssecurities51memberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_Ustreasurybillssecurities52memberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_Ustreasurybillssecurities53memberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_Ustreasurybillssecurities54memberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_Ustreasurybillssecurities55memberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_Ustreasurybillssecurities56memberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_Ustreasurybillssecurities57memberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_Ustreasurybillssecurities58memberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_Ustreasurybillssecurities59memberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_Ustreasurybillssecurities60memberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_Ustreasurybillssecurities61memberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=usl_Ustreasurybillssecurities62memberMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=usl_NymexWtiCrudeOilFuturesClAugust2016ContractsExpiringJuly2016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=usl_NymexWtiCrudeOilFuturesClSeptember2016ContractsExpiringAugust2016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=usl_NymexWtiCrudeOilFuturesClOctober2016ContractsExpiringSeptember2016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=usl_NymexWtiCrudeOilFuturesClNovember2016ContractsExpiringOctober2016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=usl_NymexWtiCrudeOilFuturesClDecember2016ContractsExpiringNovember2016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=usl_NymexWtiCrudeOilFuturesClJanuary2017ContractsExpiringDecember2016Member
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=usl_NymexWtiCrudeOilFuturesClFebruary2017ContractsExpiringJanuary2017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=usl_NymexWtiCrudeOilFuturesClMarch2017ContractsExpiringFebruary2017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=usl_NymexWtiCrudeOilFuturesClApril2017ContractsExpiringMarch2017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=usl_NymexWtiCrudeOilFuturesClMay2017ContractsExpiringApril2017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=usl_NymexWtiCrudeOilFuturesClJune2017ContractsExpiringMay2017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=usl_NymexWtiCrudeOilFuturesClJuly2017ContractsExpiringJune2017Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=usl_NymexWtiCrudeOilFuturesClFebruary2016ContractsExpiringJanuary2016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=usl_NymexWtiCrudeOilFuturesClMarch2016ContractsExpiringFebruary2016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=usl_NymexWtiCrudeOilFuturesClApril2016ContractsExpiringMarch2016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=usl_NymexWtiCrudeOilFuturesClMay2016ContractsExpiringApril2016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=usl_NymexWtiCrudeOilFuturesClJune2016ContractsExpiringMay2016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | invest_InvestmentSecuritiesSeriesAxis=usl_NymexWtiCrudeOilFuturesClJuly2016ContractsExpiringJune2016Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |