CONTRACTS AND AGREEMENTS (Details)	12 Months Ended
Dec. 31, 2019 USD ($) $ / item
Long-Duration Contracts, Assumptions by Product and Guarantee
Annual fee for custody, fund accounting and fund administration services	$ 75,000
Marketing Agreement
Long-Duration Contracts, Assumptions by Product and Guarantee
Marketing fee exclusive of the incentive fee	$ 425,000
Marketing Agreement \| USOF's assets from $0- $500 million
Long-Duration Contracts, Assumptions by Product and Guarantee
Fee percentage	0.00%
Marketing Agreement \| USOF's assets from $0- $500 million \| Minimum
Long-Duration Contracts, Assumptions by Product and Guarantee
Base amount for determining fee percentage	$ 0
Marketing Agreement \| USOF's assets from $0- $500 million \| Maximum
Long-Duration Contracts, Assumptions by Product and Guarantee
Base amount for determining fee percentage	$ 500,000,000
Marketing Agreement \| USOF's assets from $500 million - $4 billion
Long-Duration Contracts, Assumptions by Product and Guarantee
Fee percentage	0.04%
Marketing Agreement \| USOF's assets from $500 million - $4 billion \| Minimum
Long-Duration Contracts, Assumptions by Product and Guarantee
Base amount for determining fee percentage	$ 500,000,000
Marketing Agreement \| USOF's assets from $500 million - $4 billion \| Maximum
Long-Duration Contracts, Assumptions by Product and Guarantee
Base amount for determining fee percentage	$ 4,000,000,000
Marketing Agreement \| USOF's assets in excess of $4 billion
Long-Duration Contracts, Assumptions by Product and Guarantee
Fee percentage	0.03%
Ratio of expense to Average Net Assets	10.00%
Marketing Agreement \| USOF's assets in excess of $4 billion \| Minimum
Long-Duration Contracts, Assumptions by Product and Guarantee
Base amount for determining fee percentage	$ 4,000,000,000
Brown Brothers Harriman & Co. Agreements
Long-Duration Contracts, Assumptions by Product and Guarantee
Annual fee for transfer agency services	20,000
Brown Brothers Harriman & Co. Agreements \| Minimum
Long-Duration Contracts, Assumptions by Product and Guarantee
Annual fee for custody, fund accounting and fund administration services	$ 75,000
Transaction fees per transaction \| $ / item	7
Brown Brothers Harriman & Co. Agreements \| Maximum
Long-Duration Contracts, Assumptions by Product and Guarantee
Transaction fees per transaction \| $ / item	15
Brown Brothers Harriman & Co. Agreements \| First $500 million of USOF's, USNG's, US12OF's, UGA's, USDHO's, USSO's, US12NG's, USBO's, USCI's, CPER's, USAG's and USMI's combined net assets
Long-Duration Contracts, Assumptions by Product and Guarantee
Fee percentage	0.06%
Base amount for determining fee percentage	$ 500,000,000
Brown Brothers Harriman & Co. Agreements \| USOF's, USNG's, US12OF's, UGA's, USDHO's, USSO's, US12NG's, USBO's, USCI's, CPER's, USAG's and USMI's combined net assets greater than $500 million but less than $1 billion
Long-Duration Contracts, Assumptions by Product and Guarantee
Fee percentage	0.0465%
Brown Brothers Harriman & Co. Agreements \| USOF's, USNG's, US12OF's, UGA's, USDHO's, USSO's, US12NG's, USBO's, USCI's, CPER's, USAG's and USMI's combined net assets greater than $500 million but less than $1 billion \| Minimum
Long-Duration Contracts, Assumptions by Product and Guarantee
Base amount for determining fee percentage	$ 500,000,000
Brown Brothers Harriman & Co. Agreements \| USOF's, USNG's, US12OF's, UGA's, USDHO's, USSO's, US12NG's, USBO's, USCI's, CPER's, USAG's and USMI's combined net assets greater than $500 million but less than $1 billion \| Maximum
Long-Duration Contracts, Assumptions by Product and Guarantee
Base amount for determining fee percentage	$ 1,000,000,000
Brown Brothers Harriman & Co. Agreements \| USOF's, USNG's, US12OF's, UGA's, USDHO's, USSO's, US12NG's, USBO's, USCI's, CPER's, USAG's and USMI's combined net assets exceed $1 billion
Long-Duration Contracts, Assumptions by Product and Guarantee
Fee percentage	0.035%
Base amount for determining fee percentage	$ 1,000,000,000
Brokerage and Futures Commission Merchant Agreements \| Minimum
Long-Duration Contracts, Assumptions by Product and Guarantee
Commissions per round-turn trade, including applicable exchange and NFA fees for Oil Futures Contracts and options on Oil Futures Contracts \| $ / item	7
Brokerage and Futures Commission Merchant Agreements \| Maximum
Long-Duration Contracts, Assumptions by Product and Guarantee
Commissions per round-turn trade, including applicable exchange and NFA fees for Oil Futures Contracts and options on Oil Futures Contracts \| $ / item	8

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.

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 210.5-03.3)
-URI http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

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Expenditures for planning and executing the conception, pricing, promotion, and distribution of ideas, goods, and services. Costs of public relations and corporate promotions are typically considered to be marketing costs.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
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+ 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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