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Contracts and Agreements (Additional Information) (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Annual Fee for transfer agency services	$ 20,000
Brokerage commissions	3,982	4,890
Ratio of expense to Average Net Assets	0.01%	0.01%
Maximum [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Transaction fees per transaction	15
Commissions per round-turn trade, including applicable exchange and NFA fees for Oil Futures Contracts and options on Oil Futures Contracts	15
Minimum [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Annual Fee for transfer agency services	75,000
Transaction fees per transaction	7
Commissions per round-turn trade, including applicable exchange and NFA fees for Oil Futures Contracts and options on Oil Futures Contracts	7
Re balancing Investments Transaction [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Brokerage commissions	1,852	2,717
Trades Necessitated By Creation And Redemption Activity [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Brokerage commissions	2,130	2,318
First $500 million of US12OF's, USOF's, USNG's, UGA's, USDHO's, USSO's, US12NG's, USBO's, USCI's, CPER's, USAG's and USMI's combined net assets [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Fee percentage	0.06%
First $500 million of US12OF's, USOF's, USNG's, UGA's, USDHO's, USSO's, US12NG's, USBO's, USCI's, CPER's, USAG's and USMI's combined net assets [Member] | Maximum [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Base amount for determining fee percentage	500,000,000
US12OF's, USOF's, USNG's, UGA's, USDHO's, USSO's, US12NG's, USBO's, USCI's, CPER's, USAG's and USMI's combined net assets greater than $500 million but less than $1 billion [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Fee percentage	0.0465%
US12OF's, USOF's, USNG's, UGA's, USDHO's, USSO's, US12NG's, USBO'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]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Base amount for determining fee percentage	1,000,000,000
US12OF's, USOF's, USNG's, UGA's, USDHO's, USSO's, US12NG's, USBO'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]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Base amount for determining fee percentage	500,000,000
US12OF's, USOF's, USNG's, UGA's, USDHO's, USSO's, US12NG's, USBO's, USCI's, CPER's, USAG's and USMI's combined net assets exceed $1 billion [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Fee percentage	0.035%
US12OF's, USOF's, USNG's, UGA's, USDHO's, USSO's, US12NG's, USBO's, USCI's, CPER's, USAG's and USMI's combined net assets exceed $1 billion [Member] | Minimum [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Base amount for determining fee percentage	1,000,000,000
Marketing Agreement [Member] | US12OF's assets up to $3 billion [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Fee percentage	0.06%
Marketing Agreement [Member] | US12OF's assets up to $3 billion [Member] | Maximum [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Base amount for determining fee percentage	3,000,000,000
Marketing Agreement [Member] | US12OF's assets in excess of $3 billion [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Fee percentage	0.04%
Marketing Agreement [Member] | US12OF's assets in excess of $3 billion [Member] | Minimum [Member]
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items]
Base amount for determining fee percentage	$ 3,000,000,000

X

- Definition

Those fees charged for services related to holding, advising, and managing customer investment assets. These account fees usually charged annually or semi-annually, on a per security basis, for the costs of services.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.3)

-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

+ Details

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Balance Type:	debit
Period Type:	duration

X

- 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.

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X

- Definition

Base Fee Percentage

+ References

No definition available.

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- Definition

Basis Amount for Fee Percentage

+ References

No definition available.

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- Definition

Commissions Paid

+ References

No definition available.

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X

- Definition

Ratio Of Expenses To Average Net Assets

+ References

No definition available.

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- Definition

Transaction Fees Paid

+ References

No definition available.

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