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FEES PAID BY THE FUND AND RELATED PARTY TRANSACTIONS - Additional Information (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019
Fees Paid and Related Party Transactions [Line Items]
Percentage of management fee in average daily total net assets	0.60%
Licensing fee incurred	$ 1,707	$ 2,215		$ 2,215
Estimated directors' fees and expenses	$ 3,122	$ 3,267
Scenario Forecast
Fees Paid and Related Party Transactions [Line Items]
Investor tax reporting cost			$ 124,000
Estimated directors' fees and expenses			12,000
USL and the Related Public Funds, other than USCI, USAG, CPER and USMI | Scenario Forecast
Fees Paid and Related Party Transactions [Line Items]
Estimated directors' fees and expenses			$ 574,000
On and after October 20, 2011
Fees Paid and Related Party Transactions [Line Items]
Fee percentage	0.015%

X

- Definition

Noninterest expense related to directors' fees which are fees paid by an Entity to its directors. Directors' fees may be paid in addition to salary and other benefits.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 220
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.14)
-URI http://asc.fasb.org/extlink&oid=116637391&loc=SL114874048-224260

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- Definition

Amount of general expenses not normally included in Other Operating Costs and Expenses.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.6)
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

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- Definition

Base Fee Percentage

+ References

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Fees Paid and Related Party Transactions [Line Items]

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- Definition

It represent the value of license fees and other offering expenses.

+ References

No definition available.

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- Definition

Percentage of Management Fee In Average Daily Total Net Assets.

+ References

No definition available.

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