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Fair Value Of Financial Instruments (Fair Value of Derivative Instruments) (Detail) - USD ($) | Jun. 30, 2015 | Dec. 31, 2014
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Futures [Member] | Commodity Contracts [Member] | Assets [Member] |  |
Derivatives, Fair Value [Line Items] |  |
Derivatives not Accounted for as Hedging Instruments | $ (47,173,255) | $ (167,617,930)

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- Definition Fair value as of the balance sheet date of derivative instrument not designated as hedging instrument and classified as an asset. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4B -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=56946850&loc=SL5624163-113959 + Details
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Balance Type: | debit
Period Type: | instant

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Details
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- Details
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- Details
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