XML 18 R3.htm IDEA: XBRL DOCUMENT v3.19.1

Condensed Schedule of Investments	Mar. 31, 2019 USD ($)
Value/ Unrealized Gain (Loss) on Open Commodity Contracts	$ (1,177,875)
Open Futures Contracts, Long
Notional Amount	$ 63,114,985	[1]
Number of Contracts	1,030	[1]
Value/ Unrealized Gain (Loss) on Open Commodity Contracts	$ (1,177,875)	[1]
% of Partners' Capital	(1.90%)	[1]
Open Futures Contracts, Long | United States | NYMEX WTI Crude Oil Futures CL May 2019 contracts expiring April 2019
Notional Amount	$ 5,039,924
Number of Contracts	86
Value/ Unrealized Gain (Loss) on Open Commodity Contracts	$ 132,116
% of Partners' Capital	0.21%
Open Futures Contracts, Long | United States | NYMEX WTI Crude Oil Futures CL June 2019 contracts expiring May 2019
Notional Amount	$ 5,449,224
Number of Contracts	86
Value/ Unrealized Gain (Loss) on Open Commodity Contracts	$ (265,144)
% of Partners' Capital	(0.43%)
Open Futures Contracts, Long | United States | NYMEX WTI Crude Oil Futures CL July 2019 contracts expiring June 2019
Notional Amount	$ 5,348,324
Number of Contracts	86
Value/ Unrealized Gain (Loss) on Open Commodity Contracts	$ (153,924)
% of Partners' Capital	(0.25%)
Open Futures Contracts, Long | United States | NYMEX WTI Crude Oil Futures CL August 2019 contracts expiring July 2019 [Member]
Notional Amount	$ 5,574,042
Number of Contracts	86
Value/ Unrealized Gain (Loss) on Open Commodity Contracts	$ (371,902)
% of Partners' Capital	(0.60%)
Open Futures Contracts, Long | United States | NYMEX WTI Crude Oil Futures CL September 2019 contracts expiring August 2019 [Member]
Notional Amount	$ 5,570,622
Number of Contracts	86
Value/ Unrealized Gain (Loss) on Open Commodity Contracts	$ (365,042)
% of Partners' Capital	(0.59%)
Open Futures Contracts, Long | United States | NYMEX WTI Crude Oil Futures CL October 2019 contracts expiring September 2019 [Member]
Notional Amount	$ 5,510,732
Number of Contracts	85
Value/ Unrealized Gain (Loss) on Open Commodity Contracts	$ (370,782)
% of Partners' Capital	(0.60%)
Open Futures Contracts, Long | United States | NYMEX WTI Crude Oil Futures CL November 2019 contracts expiring October 2019 [Member]
Notional Amount	$ 6,197,604
Number of Contracts	86
Value/ Unrealized Gain (Loss) on Open Commodity Contracts	$ (1,005,784)
% of Partners' Capital	(1.62%)
Open Futures Contracts, Long | United States | NYMEX WTI Crude Oil Futures CL December 2019 contracts expiring November 2019 [Member]
Notional Amount	$ 5,472,818
Number of Contracts	86
Value/ Unrealized Gain (Loss) on Open Commodity Contracts	$ (293,898)
% of Partners' Capital	(0.47%)
Open Futures Contracts, Long | United States | NYMEX WTI Crude Oil Futures CL January 2020 contracts expiring December 2019 [Member]
Notional Amount	$ 4,544,695
Number of Contracts	85
Value/ Unrealized Gain (Loss) on Open Commodity Contracts	$ 557,005
% of Partners' Capital	0.90%
Open Futures Contracts, Long | United States | NYMEX WTI Crude Oil Futures CL February 2020 contracts, expiring January 2020
Notional Amount	$ 4,547,197
Number of Contracts	86
Value/ Unrealized Gain (Loss) on Open Commodity Contracts	$ 595,603
% of Partners' Capital	0.96%
Open Futures Contracts, Long | United States | NYMEX WTI Crude Oil Futures CL March 2020 contracts, expiring February 2020
Notional Amount	$ 4,848,883
Number of Contracts	86
Value/ Unrealized Gain (Loss) on Open Commodity Contracts	$ 273,277
% of Partners' Capital	0.44%
Open Futures Contracts, Long | United States | NYMEX WTI Crude Oil Futures CL April 2020 contracts, expiring March 2020
Notional Amount	$ 5,010,920
Number of Contracts	86
Value/ Unrealized Gain (Loss) on Open Commodity Contracts	$ 90,600
% of Partners' Capital	0.15%
Cash Equivalents
Market Value	$ 57,747,139
% of Partners' Capital	93.24%
Cash Equivalents | United States Treasury Obligations
Market Value	$ 40,747,139
% of Partners' Capital	65.79%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.37%, 4/04/2019
Principal Amount	$ 1,000,000
Market Value	$ 999,805
% of Partners' Capital	1.61%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.41%, 4/11/2019
Principal Amount	$ 2,000,000
Market Value	$ 1,998,675
% of Partners' Capital	3.23%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.42%, 4/18/2019
Principal Amount	$ 2,000,000
Market Value	$ 1,997,738
% of Partners' Capital	3.23%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.43%, 4/25/2019
Principal Amount	$ 2,000,000
Market Value	$ 1,996,800
% of Partners' Capital	3.22%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.46%, 5/02/2019
Principal Amount	$ 2,000,000
Market Value	$ 1,995,824
% of Partners' Capital	3.22%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.47%, 5/09/2019
Principal Amount	$ 2,000,000
Market Value	$ 1,994,859
% of Partners' Capital	3.22%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.48%, 5/16/2019
Principal Amount	$ 1,000,000
Market Value	$ 996,938
% of Partners' Capital	1.61%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.50%, 5/23/2019
Principal Amount	$ 1,000,000
Market Value	$ 996,440
% of Partners' Capital	1.61%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.49%, 5/30/2019
Principal Amount	$ 1,000,000
Market Value	$ 995,972
% of Partners' Capital	1.61%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.51%, 6/06/2019
Principal Amount	$ 2,000,000
Market Value	$ 1,990,925
% of Partners' Capital	3.21%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.51%, 6/13/2019
Principal Amount	$ 2,000,000
Market Value	$ 1,989,942
% of Partners' Capital	3.21%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.49%, 6/20/2019
Principal Amount	$ 1,000,000
Market Value	$ 994,533
% of Partners' Capital	1.61%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.47%, 7/05/2019
Principal Amount	$ 1,000,000
Market Value	$ 993,574
% of Partners' Capital	1.60%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.48%, 7/11/2019
Principal Amount	$ 2,000,000
Market Value	$ 1,986,239
% of Partners' Capital	3.21%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.47%, 7/18/2019
Principal Amount	$ 2,000,000
Market Value	$ 1,985,360
% of Partners' Capital	3.21%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.47%, 7/25/2019
Principal Amount	$ 2,000,000
Market Value	$ 1,984,411
% of Partners' Capital	3.20%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.48%, 8/01/2019
Principal Amount	$ 1,000,000
Market Value	$ 991,697
% of Partners' Capital	1.60%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.46%, 8/08/2019
Principal Amount	$ 2,000,000
Market Value	$ 1,982,585
% of Partners' Capital	3.20%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.47%, 8/15/2019
Principal Amount	$ 2,000,000
Market Value	$ 1,981,564
% of Partners' Capital	3.20%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.47%, 8/22/2019
Principal Amount	$ 2,000,000
Market Value	$ 1,980,655
% of Partners' Capital	3.20%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.48%, 8/29/2019
Principal Amount	$ 2,000,000
Market Value	$ 1,979,583
% of Partners' Capital	3.20%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.48%, 9/05/2019
Principal Amount	$ 2,000,000
Market Value	$ 1,978,631
% of Partners' Capital	3.19%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.48%, 9/12/2019
Principal Amount	$ 2,000,000
Market Value	$ 1,977,723
% of Partners' Capital	3.19%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.46%, 9/19/2019
Principal Amount	$ 1,000,000
Market Value	$ 988,458
% of Partners' Capital	1.60%
Cash Equivalents | United States Treasury Obligations | U.S. Treasury Bills 2.41%, 9/26/2019
Principal Amount	$ 1,000,000
Market Value	$ 988,208
% of Partners' Capital	1.60%
Cash Equivalents | United States | United States - Money Market Funds
Market Value	$ 17,000,000
% of Partners' Capital	27.45%
Cash Equivalents | United States | United States - Money Market Funds | Fidelity Investments Money Market Funds - Government Portfolio [Member]
Principal Amount	$ 2,000,000
Market Value	$ 2,000,000
% of Partners' Capital	3.23%
Cash Equivalents | United States | United States - Money Market Funds | Goldman Sachs Financial Square Funds - Government Fund - Class FS [Member]
Principal Amount	$ 7,000,000
Market Value	$ 7,000,000
% of Partners' Capital	11.30%
Cash Equivalents | United States | United States - Money Market Funds | Morgan Stanley Institutional Liquidity Funds - Government Portfolio [Member]
Principal Amount	$ 8,000,000
Market Value	$ 8,000,000
% of Partners' Capital	12.92%
[1] Collateral amounted to $10,092,231 on open futures contracts.

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

- Definition

Percentage of Partners Capital

+ References

No definition available.

+ Details

Name:	usl_PercentageOfPartnersCapital
Namespace Prefix:	usl_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Unrealized gain (loss) on open commodity futures contracts.

+ References

No definition available.

+ Details

Name:	usl_UnrealizedGainLossOnOpenCommodityFuturesContracts
Namespace Prefix:	usl_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Details

Name:	us-gaap_InvestmentTypeAxis=usl_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=usl_NYMEXWTICrudeOilFuturesCLMay2019ContractsExpiringApril2019Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_NYMEXWTICrudeOilFuturesCLJune2019ContractsExpiringMay2019Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_NYMEXWTICrudeOilFuturesCLJuly2019ContractsExpiringJune2019Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_NYMEXWTICrudeOilFuturesCLAugust2019ContractsExpiringJuly2019Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_NYMEXWTICrudeOilFuturesCLSeptember2019ContractsExpiringAugust2019Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_NYMEXWTICrudeOilFuturesCLOctober2019ContractsExpiringSeptember2019Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_NYMEXWTICrudeOilFuturesCLNovember2019ContractsExpiringOctober2019Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_NYMEXWTICrudeOilFuturesCLDecember2019ContractsExpiringNovember2019Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_NYMEXWTICrudeOilFuturesCLJanuary2020ContractsExpiringDecember2019Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_NymexWtiCrudeOilFuturesClFebruary2020ContractsExpiringJanuary2020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_NymexWtiCrudeOilFuturesClMarch2020ContractsExpiringFebruary2020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_NymexWtiCrudeOilFuturesClApril2020ContractsExpiringMarch2020Member
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=usl_UsTreasuryBillSecuritiesOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_UsTreasuryBillSecuritiesTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_UsTreasuryBillSecuritiesThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_UsTreasuryBillSecuritiesFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_UsTreasuryBillSecuritiesFiveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_UsTreasuryBillSecuritiesSixMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_UsTreasuryBillSecuritiesSevenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_UsTreasuryBillSecuritiesEightMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_UsTreasuryBillSecuritiesNineMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_UsTreasuryBillSecuritiesTenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_UsTreasuryBillSecuritiesElevenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_USTreasuryBillSecuritiesTwelveMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_UsTreasuryBillSecuritiesThirteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_UsTreasuryBillSecuritiesFourteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_USTreasuryBillSecuritiesFifteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_USTreasuryBillSecuritiesSixteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_USTreasuryBillSecuritiesSeventeenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_USTreasuryBillSecuritiesEighteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_USTreasuryBillSecuritiesNineteenMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_USTreasuryBillSecuritiesTwentyMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_USTreasuryBillSecuritiesTwentyOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_USTreasuryBillSecuritiesTwentyTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_USTreasuryBillSecuritiesTwentyThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_USTreasuryBillSecuritiesTwentyFourMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	invest_InvestmentSecuritiesSeriesAxis=usl_USTreasuryBillSecuritiesTwentyFiveMember
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:	us-gaap_DerivativeInstrumentRiskAxis=usl_FidelityInvestmentsMoneyMarketFundsGovernmentPortfolioMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=usl_GoldmanSachsFinancialSquareFundsGovernmentFundClassFsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=usl_MorganStanleyInstitutionalLiquidityFundsGovernmentPortfolioMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: