XML 45 R26.htm IDEA: XBRL DOCUMENT
v2.4.0.6

FINANCIAL HIGHLIGHTS (Details) (USD $) | 9 Months Ended
--- | ---
Sep. 30, 2012 | Sep. 30, 2011
Per Unit Operating Performance: |  |  |  |
Net Asset Value, beginning of period | $ 74.54 |  | $ 63.08 |
Total income (loss) | $ 7.25 |  | $ 6.73 |
Total expenses | $ (0.59) |  | $ (0.56) |
Net increase in net asset value | $ 6.66 |  | $ 6.17 |
Net Asset Value Per Unit: | $ 81.20 |  | $ 69.25 |
Total Return | 8.93% |  | 9.78% |
Ratios to Average Net Assets |  |  |  |
Total income (loss) | 8.40% |  | 7.80% |
Management fees* | 0.75% | [1] | 0.75% | [1]
Total expenses excluding management fees* | 0.30% | [1] | 0.60% | [1]
Expenses waived* | (0.07%) | [1] | (0.37%) | [1]
Net expenses excluding management fees* | 0.23% | [1] | 0.23% | [1]
Net income (loss) | 7.66% |  | 7.07% |
[1] | Total returns are calculated based on the change in value during the period. An individual unitholder's total return and ratio may vary from the above total returns and ratios based on the timing of contributions to and withdrawals from USBO.

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

X
- Definition Representing per share value net increase decrease in net asset. + References No definition available. + Details
Name: | bno_NetIncreaseDecreaseInNetAssetValue
Namespace Prefix: | bno_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

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

X
- Definition Representing percentage value of total expenses waived on net assets. + References No definition available. + Details
Name: | bno_PercentageOfExpensesWaivedOnNetAssets
Namespace Prefix: | bno_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Representing percentage value of management feeson net assets. + References No definition available. + Details
Name: | bno_PercentageOfManagementFeesOnNetAssets
Namespace Prefix: | bno_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Representing percentage value of net expenses excluding management fees on net assets. + References No definition available. + Details
Name: | bno_PercentageOfNetExpensesExcludingManagementFeeOnNetAssets
Namespace Prefix: | bno_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Representing percentage value of net income on net assets. + References No definition available. + Details
Name: | bno_PercentageOfNetIncomeOnNetAssets
Namespace Prefix: | bno_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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

X
- Definition Representing percentage value of total expenses excluding management fees on net assets. + References No definition available. + Details
Name: | bno_PercentageOfTotalExpensesExcludingManagementFeesOnNetAssets
Namespace Prefix: | bno_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Representing percentage value of total income on net assets. + References No definition available. + Details
Name: | bno_PercentageOfTotalIncomeOnNetAssets
Namespace Prefix: | bno_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Representing percentage of total return. + References No definition available. + Details
Name: | bno_PercentageOfTotalReturn
Namespace Prefix: | bno_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Representing per share value of total expense. + References No definition available. + Details
Name: | bno_TotalExpensePerUnit
Namespace Prefix: | bno_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Representing per share value of total income. + References No definition available. + Details
Name: | bno_TotalIncomePerUnit
Namespace Prefix: | bno_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration