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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Additional Information (Details) - Creation Baskets | Sep. 30, 2020 USD ($) $ / item
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Significant Accounting Policies [Line Items] |
Number of Shares per basket | $ / item | 50,000
Fee paid by Authorized Purchasers for each order placed to create one or more Creation Baskets or to redeem one or more baskets | $ | $ 350

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- Definition Fee Paid Per Order + References No definition available. + Details
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- Definition Number of Shares per Basket. + References No definition available. + Details
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Namespace Prefix: | usl_
Data Type: | srt-types:perUnitItemType
Balance Type: | na
Period Type: | instant

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- Definition Significant Accounting Policies [Line Items] + References No definition available. + Details
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Namespace Prefix: | usl_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |