XML 26 R28.htm IDEA: XBRL DOCUMENT
v2.4.0.6

FINANCIAL HIGHLIGHTS (Per Unit Performance Data and Other Supplemental Financial Data) (Details) (USD $) | 12 Months Ended |
--- | --- | ---
Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2010 | Nov. 18, 2009
Per Unit Operating Performance: |  |  |  |
Net asset value, beginning of year | $ 21.21 | $ 35.02 | $ 53.77 | $ 50.00
Total income (loss) | $ (3.78) | $ (13.42) | $ (18.21) |
Net expenses | $ (0.20) | $ (0.39) | $ (0.54) |
Net decrease in net asset value | $ (3.98) | $ (13.81) | $ (18.75) |
Net asset value, end of year | $ 17.23 | $ 21.21 | $ 35.02 | $ 50.00
Total Return | (18.76%) | (39.43%) | (34.87%) |
Ratios to Average Net Assets |  |  |  |
Total income (loss) | (11.80%) | (44.03%) | (37.65%) |
Management fees | 0.75% | 0.75% | 0.70% |
Total expenses excluding management fees | 0.40% | 0.53% | 0.66% |
Expenses waived | (0.18%) | (0.36%) | (0.43%) |
Net expenses excluding management fees | 0.22% | 0.17% | 0.23% |
Net income (loss) | (12.77%) | (44.95%) | (38.58%) |

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

X
- Definition Expense Excluding Management Fee Percentage Net + References No definition available. + Details
Name: | unl_ExpenseExcludingManagementFeePercentageNet
Namespace Prefix: | unl_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Expenses, Excluding Management Fee Percentage + References No definition available. + Details
Name: | unl_ExpensesExcludingManagementFeePercentage
Namespace Prefix: | unl_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Increase (Decrease) In Net Asset Value Per Unit + References No definition available. + Details
Name: | unl_IncreaseDecreaseInNetAssetValuePerUnit
Namespace Prefix: | unl_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Management Incentive Fee Percentage + References No definition available. + Details
Name: | unl_ManagementIncentiveFeePercentage
Namespace Prefix: | unl_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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 Percentage of Consolidated Net Income + References No definition available. + Details
Name: | unl_PercentageOfConsolidatedNetIncome
Namespace Prefix: | unl_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of Total Revenue + References No definition available. + Details
Name: | unl_PercentageOfTotalRevenue
Namespace Prefix: | unl_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage Waiver Expense + References No definition available. + Details
Name: | unl_PercentageWaiverExpense
Namespace Prefix: | unl_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Rate Of Return On Average Asset + References No definition available. + Details
Name: | unl_RateOfReturnOnAverageAsset
Namespace Prefix: | unl_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Total Expenses, Per Unit + References No definition available. + Details
Name: | unl_TotalExpensesPerUnit
Namespace Prefix: | unl_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Total Income (Loss), Per Unit + References No definition available. + Details
Name: | unl_TotalIncomeLossPerUnit
Namespace Prefix: | unl_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_IncreaseDecreaseInPartnersCapitalRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration