XML 27 R22.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Organization and Business - Additional Information (Detail) (USD $) | 1 Months Ended |  |  |  |  |  |
--- | --- | --- | --- | --- | --- | --- | ---
Nov. 30, 2009 PartnershipUnit | Nov. 18, 2009 | Sep. 30, 2012 PartnershipUnit | Dec. 31, 2011 | Sep. 30, 2011 | Dec. 31, 2010 | Feb. 29, 2012 Creation Baskets | Feb. 29, 2012 Prior to February 29, 2012 Creation Baskets | Sep. 30, 2012 Open Cleared Swap and Futures Contracts Open Futures Contracts, Long United States Contract
Organization, Consolidation and Presentation of Financial Statements Disclosure [Line Items] |  |  |  |  |  |  |  |  |
Number of contracts |  |  |  |  |  |  |  |  | 1,373
Number of units per basket |  |  |  |  |  |  | $ 50,000 | $ 100,000 |
Fee paid by Authorized Purchasers for each order placed to create one or more Creation Baskets or to redeem one or more baskets |  |  | $ 350 |  | $ 1,000 |  |  |  |
Number of initially registered units on Form S-1 with the U.S. Securities and Exchange Commission | 30,000,000 |  |  |  |  |  |  |  |
Net asset value per unit |  | $ 50.00 | $ 18.68 | $ 21.21 | $ 27.94 | $ 35.02 |  |  |
Number of units issued |  | 200,000 |  |  |  |  |  |  |
Value of unit issued |  | $ 10,000,000 |  |  |  |  |  |  |
Commenced investment operations date |  | Nov. 18, 2009 |  |  |  |  |  |  |
Number of registered units |  |  | 30,000,000 |  |  |  |  |  |

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

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

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

X
- Definition Number of Units per Basket + References No definition available. + Details
Name: | unl_NumberOfUnitsPerBasket
Namespace Prefix: | unl_
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: | unl_NumberOfUnitsRegisteredInPeriod
Namespace Prefix: | unl_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | unl_OrganizationConsolidationAndPresentationOfFinancialStatementsDisclosureLineItems
Namespace Prefix: | unl_
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: | unl_UnitsIssuedDuringPeriodUnitsNewIssues
Namespace Prefix: | unl_
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: | unl_UnitsIssuedDuringPeriodValueNewIssues
Namespace Prefix: | unl_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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 6 -Subparagraph (SX 210.12-14.Column B) -URI http://asc.fasb.org/extlink&oid=6955306&loc=d3e611322-123010 Reference 2: 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 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 12C -Paragraph Column B -Article 12 Reference 4: 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 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 Date the operations of the entity commenced, in CCYY-MM-DD format. + References No definition available. + Details
Name: | us-gaap_OperationsCommencedDate1
Namespace Prefix: | us-gaap_
Data Type: | xbrli:dateItemType
Balance Type: | na
Period Type: | duration