XML 35 R19.htm IDEA: XBRL DOCUMENT
v3.5.0.2

FINANCIAL HIGHLIGHTS (Tables) | 9 Months Ended
--- | ---
Sep. 30, 2016
Financial Highlights [Abstract] |
Per Unit Performance Data and Other Supplemental Financial Data | The following table presents per share performance data and other supplemental financial data for the nine months ended September 30, 2016 and 2015 for the shareholders. This information has been derived from information presented in the condensed financial statements.
|  | For the nine |  | For the nine |
|  | months ended |  | months ended |
|  | September 30, |  | September 30, |
|  | 2016 |  | 2015 |
|  | (Unaudited) |  | (Unaudited) |
Per Share Operating Performance: |  |  |  |  |  |  |
Net asset value, beginning of period |  | $ | 17.00 |  | $ | 26.59 |
Total income (loss) |  |  | 1.84 |  |  | (5.99) |
Total expenses |  |  | (0.09) |  |  | (0.15) |
Net increase (decrease) in net asset value |  |  | 1.75 |  |  | (6.14) |
Net asset value, end of period |  | $ | 18.75 |  | $ | 20.45 |
Total Return |  |  | 10.29 | % |  | (23.09) | %
Ratios to Average Net Assets |  |  |  |  |  |  |
Total income (loss) |  |  | 17.46 | % |  | (20.93) | %
Management fees* |  |  | 0.60 | % |  | 0.60 | %
Expenses excluding management fees* |  |  | 0.12 | % |  | 0.20 | %
Net income (loss) |  |  | 16.91 | % |  | (21.53) | %
* Annualized.

X
- References No definition available. + Details
Name: | usl_FinancialHighlightsAbstract
Namespace Prefix: | usl_
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: | usl_PerUnitPerformanceDataAndOtherSupplementalFinancialDataTableTextBlock
Namespace Prefix: | usl_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration