CONTRACTS AND AGREEMENTS (Additional Information) (Details)	9 Months Ended
Sep. 30, 2016 USD ($) $ / Units
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Annual Fee for transfer agency services	$ 20,000
Maximum [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Transaction fees per transaction	$ 15
Commissions per round-turn trade, including applicable exchange and NFA fees for Natural Gas-Related Futures Contracts and options on Futures Contracts \| $ / Units	8
Minimum [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Annual Fee for custody, fund accounting and fund administration services	$ 75,000
Transaction fees per transaction	$ 7
Commissions per round-turn trade, including applicable exchange and NFA fees for Natural Gas-Related Futures Contracts and options on Futures Contracts \| $ / Units	7
first $500 million of the Related Public Funds' combined net assets [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Fee percentage	0.06%
first $500 million of the Related Public Funds' combined net assets [Member] \| Maximum [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Base amount for determining fee percentage	$ 500,000,000
Related Public Funds' combined net assets greater than $500 million but less than $1 billion [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Fee percentage	0.0465%
Related Public Funds' combined net assets greater than $500 million but less than $1 billion [Member] \| Maximum [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Base amount for determining fee percentage	$ 1,000,000,000
Related Public Funds' combined net assets greater than $500 million but less than $1 billion [Member] \| Minimum [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Base amount for determining fee percentage	$ 500,000,000
Related Public Funds' combined net assets exceed $1 billion [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Fee percentage	0.035%
Related Public Funds' combined net assets exceed $1 billion [Member] \| Minimum [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Base amount for determining fee percentage	$ 1,000,000,000
Marketing Agent And Affliate Of Uscf [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Maximum Aggregate Compensation Paid For Distribution Related Services	10.00%
Marketing Agreement [Member] \| UNL's assets up to $3 billion [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Fee percentage	0.06%
Base amount for determining fee percentage	$ 3,000,000,000
Marketing Agreement [Member] \| UNL's assets in excess of $3 billion [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Fee percentage	0.04%
Base amount for determining fee percentage	$ 3,000,000,000

Base Fee Percentage

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Basis Amount for Fee Percentage

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- Definition

Commissions Paid

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- Definition

Maximum percentage of gross proceeds from offering paid for distribution related services as compensation.

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- Definition

Transaction Fees Paid

+ References

No definition available.

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- Definition

Those fees charged for services related to holding, advising, and managing customer investment assets. These account fees usually charged annually or semi-annually, on a per security basis, for the costs of services.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.3)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Fees paid to an agent employed by a corporation or mutual fund to maintain shareholder records, including purchases, sales, and account balances. Also includes custodian fees incurred during an accounting period from an agent, bank, trust company, or other organization that holds and safeguards an individual's, mutual fund's, or investment company's assets for them. These fees will be billed back to the client and are a component of noninterest expense.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.14)
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

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