XML 56 R20.htm IDEA: XBRL DOCUMENT
v2.4.0.6

FINANCIAL HIGHLIGHTS (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2012
Financial Highlights [Abstract] |
Per Unit Performance Data and Other Supplemental Financial Data | The following table presents per unit performance data and other supplemental financial data for the years ended December 31, 2012, 2011 and 2010. This information has been derived from information presented in the financial statements.
|  | Year Ended December 31, 2012 |  |  | Year Ended December 31, 2011 |  |  | Year Ended December 31, 2010 |
Per Unit Operating Performance: |  |  |  |  |  |  |  |  |  |  |  |
Net asset value, beginning of year |  | $ | 21.21 |  |  | $ | 35.02 |  |  | $ | 53.77 |
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 |
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_FinancialHighlightsAbstract
Namespace Prefix: | unl_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Per Unit Performance Data and Other Supplemental Financial Data [Table Text Block] + References No definition available. + Details
Name: | unl_PerUnitPerformanceDataAndOtherSupplementalFinancialDataTableTextBlock
Namespace Prefix: | unl_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration