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SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Details Textual) | Feb. 29, 2012
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Number Rof Units Per Baskets | 50,000
Redemption Baskets [Member] | Prior to July 1, 2011 [Member] |
Number Rof Units Per Baskets | 100,000

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- Definition Number rof Units Per Baskets. + References No definition available. + Details
Name: | bno_NumberRofUnitsPerBaskets
Namespace Prefix: | bno_
Data Type: | us-types:perUnitItemType
Balance Type: | na
Period Type: | instant