CONTRACTS AND AGREEMENTS (Details Textual) (USD $)	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
Annual Fee Payable For Transfer Agency Services	$ 20,000
Brokerage commissions	8,402	9,947
Rebalancing Cost	2,163	7,967
Creation and Redemption Activity Costs	6,238	1,904
Percentage Of Average Daily Assets Net Total	0.08%	0.07%
Maximum [Member]
Transaction fees per transaction	15
Commission Per Round Turn	15
Minimum [Member]
Annual Fee Payable For Transfer Agency Services	75,000
Transaction fees per transaction	7
Commission Per Round Turn	7
First $500 million of USBO's, USOF's, USNG's, US12OF's, UGA's, USDHO's, USSO's, US12NG's, USCI's, CPER's, USAG's and USMI's combined net asset [Member]
Fee percentage	0.06%
First $500 million of USBO's, USOF's, USNG's, US12OF's, UGA's, USDHO's, USSO's, US12NG's, USCI's, CPER's, USAG's and USMI's combined net asset [Member] \| Maximum [Member]
Base amount for determining fee percentage	500,000,000
USBO's, USOF's, USNG's, US12OF's, UGA's, USDHO's, USSO's, US12NG's, USCI's, CPER's USAG's and USMI's combined net assets greater than $500 million but less than $1 billion [Member]
Fee percentage	0.0465%
USBO's, USOF's, USNG's, US12OF's, UGA's, USDHO's, USSO's, US12NG's, USCI's, CPER's USAG's and USMI's combined net assets greater than $500 million but less than $1 billion [Member] \| Maximum [Member]
Base amount for determining fee percentage	1,000,000,000
USBO's, USOF's, USNG's, US12OF's, UGA's, USDHO's, USSO's, US12NG's, USCI's, CPER's USAG's and USMI's combined net assets greater than $500 million but less than $1 billion [Member] \| Minimum [Member]
Base amount for determining fee percentage	500,000,000
USBO's, USOF's, USNG's, US12OF's, UGA's, USDHO's, USSO's, US12NG's, USCI's, CPER's, USAG's and USMI's combined net assets exceed $1 billion [Member]
Fee percentage	0.035%
USBO's, USOF's, USNG's, US12OF's, UGA's, USDHO's, USSO's, US12NG's, USCI's, CPER's, USAG's and USMI's combined net assets exceed $1 billion [Member] \| Minimum [Member]
Base amount for determining fee percentage	1,000,000,000
Marketing Agreement [Member] \| US12NG's assets up to $3 billion [Member]
Fee percentage	0.06%
Base amount for determining fee percentage	3,000,000,000
Marketing Agreement [Member] \| US12NG's assets in excess of $3 billion [Member]
Fee percentage	0.04%
Base amount for determining fee percentage	$ 3,000,000,000

The annual fee payable for transfer agency services reported during the period.

No definition available.

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- Definition

Base Fee Percentage

+ References

No definition available.

+ Details

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- Definition

Basis Amount for Fee Percentage

+ References

No definition available.

+ Details

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Namespace Prefix:	bno_
Data Type:	xbrli:monetaryItemType
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- Definition

Represents the commissions round turn trade including exchange fees.

+ References

No definition available.

+ Details

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Namespace Prefix:	bno_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	duration

- Definition

The anount of commission accrued as a result of trades necessitated by creation and redemption activity.

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

The percentage of average daily total net assets during the period.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

The amount attributable to commission accrued as a result of rebalancing costs during the reporting period.

+ References

No definition available.

+ Details

Name:	bno_RebalancingCost
Namespace Prefix:	bno_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Transaction Fees Paid.

+ References

No definition available.

+ Details

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Namespace Prefix:	bno_
Data Type:	us-types:perUnitItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of expense during the period for floor brokerage fees paid to other broker-dealers to execute trades on their behalf, stock exchange fees, order flow fees, and clearance fees.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Audit and Accounting Guide (AAG)

-Number AAG-BRD

-Paragraph 61

-IssueDate 2006-05-01

-Chapter 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Audit and Accounting Guide (AAG)

-Number AAG-BRD

-Paragraph 60

-IssueDate 2006-05-01

-Chapter 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

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