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Contracts and Agreements - Additional Information (Detail) (USD $) | 12 Months Ended
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Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2010
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items] |  |  |
Annual Fee for transfer agency services | $ 20,000 |  |
Brokerage commissions | 21,804 | 27,427 | 13,314
Ratio of expense to Average Net Assets | 0.02% | 0.01% | 0.01%
Maximum |  |  |
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 |  |  |
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items] |  |  |
Annual Fee for custody, fund accounting and fund administration 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 |  |  |
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items] |  |  |
Brokerage commissions | 8,385 | 14,118 | 9,815
Trades Necessitated By Creation And Redemption Activity |  |  |
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items] |  |  |
Brokerage commissions | 13,419 | 13,309 | 3,499
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 |  |  |
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 | Maximum |  |  |
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 |  |  |
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 | Maximum |  |  |
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 | Minimum |  |  |
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 |  |  |
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 | Minimum |  |  |
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items] |  |  |
Base amount for determining fee percentage | 1,000,000,000 |  |
Marketing Agreement | US12OF's assets up to $3 billion |  |  |
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items] |  |  |
Fee percentage | 0.06% |  |
Marketing Agreement | US12OF's assets up to $3 billion | Maximum |  |  |
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items] |  |  |
Base amount for determining fee percentage | 3,000,000,000 |  |
Marketing Agreement | US12OF's assets in excess of $3 billion |  |  |
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items] |  |  |
Fee percentage | 0.04% |  |
Marketing Agreement | US12OF's assets in excess of $3 billion | Minimum |  |  |
Long-Duration Contracts, Assumptions by Product and Guarantee [Line Items] |  |  |
Base amount for determining fee percentage | $ 3,000,000,000 |  |

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- 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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- 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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- Definition Fees paid to an agent employed by a corporation or mutual fund to maintain shareholder records, including purchases, sales, and account balances. Also includes custodian fees incurred during an accounting period from an agent, bank, trust company, or other organization that holds and safeguards an individual's, mutual fund's, or investment company's assets for them. These fees will be billed back to the client and are a component of noninterest expense. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 225 -Section S99 -Paragraph 1 -Subparagraph (SX 210.9-04.14) -URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882 + Details
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- Definition Base Fee Percentage + References No definition available. + Details
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- Definition Commissions Paid + References No definition available. + Details
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- Definition Ratio Of Expenses To Average Net Assets + References No definition available. + Details
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