XML 50 R20.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Organization and Business (Additional Information) (Details) (USD $) | 0 Months Ended |  |  |  |
--- | --- | --- | --- | --- | ---
Dec. 04, 2007 | Dec. 06, 2007 | Mar. 31, 2014 | Dec. 31, 2013 | Mar. 31, 2013 | Dec. 31, 2012
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items] |  |  |  |  |  |  |
Fee paid by Authorized Purchasers for each order placed to create one or more Creation Baskets or to redeem one or more baskets |  |  | 350 |  |  |  |
Number of initially registered units on Form S-1 with the U.S. Securities and Exchange Commission | 11,000,000 |  |  |  |  |  |
Net asset value per share |  | $ 50.00 | $ 44.10 |  | $ 42.83 | $ 41.03 | $ 39.81
Number of shares issued |  | 300,000 |  |  |  |  |
Value of shares issued |  | $ 15,000,000 |  |  |  |  |
Number of registered shares |  |  | 111,000,000 |  |  |  |
Creation Baskets |  |  |  |  |  |  |
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items] |  |  |  |  |  |  |
Number of shares per basket |  |  | 50,000 |  |  |  |
Open Futures Contracts, Long | United States |  |  |  |  |  |  |
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items] |  |  |  |  |  |  |
Number of Contracts |  |  | 593 | [1] |  |  |
[1] | Collateral amounted to $3,086,894 on open futures contracts.

X
- Definition Balance held at close of period in number of contracts. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -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=6955306&loc=d3e611225-123010 Reference 2: http://www.xbrl.org/2003/role/presentationRef -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=6955306&loc=d3e611322-123010 Reference 3: http://www.xbrl.org/2003/role/presentationRef -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=6955306&loc=d3e611133-123010 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 12C -Paragraph Column B -Article 12 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 12 -Paragraph Column B -Article 12 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 14 -Paragraph Column B -Article 12 + Details
Name: | us-gaap_InvestmentOwnedBalanceContracts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:decimalItemType
Balance Type: | na
Period Type: | instant

X
- Definition Fee Paid Per Order + References No definition available. + Details
Name: | usl_FeePaidPerOrder
Namespace Prefix: | usl_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | instant

X
- Definition Net asset value per unit. + References No definition available. + Details
Name: | usl_NetAssetValuePerUnit
Namespace Prefix: | usl_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of Registered Units + References No definition available. + Details
Name: | usl_NumberOfRegisteredUnits
Namespace Prefix: | usl_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of Units per Basket + References No definition available. + Details
Name: | usl_NumberOfUnitsPerBasket
Namespace Prefix: | usl_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of Units Registered in Period + References No definition available. + Details
Name: | usl_NumberOfUnitsRegisteredInPeriod
Namespace Prefix: | usl_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | usl_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems
Namespace Prefix: | usl_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Units Issued During Period, Units, New Issues + References No definition available. + Details
Name: | usl_UnitsIssuedDuringPeriodUnitsNewIssues
Namespace Prefix: | usl_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Definition Units Issued During Period, Value, New Issues + References No definition available. + Details
Name: | usl_UnitsIssuedDuringPeriodValueNewIssues
Namespace Prefix: | usl_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration