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FAIR VALUE OF FINANCIAL INSTRUMENTS (Valuation of Securities Using Fair Value Hierarchy) (Detail) - USD ($) | Mar. 31, 2016 | Dec. 31, 2015
--- | --- | ---
Short-Term Investments [Member] |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |
Securities, fair value | $ 2,617,817,593 | $ 2,468,495,664
Exchange-Traded Futures Contracts [Member] | United States [Member] |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |
Securities, fair value | (96,981,140) | (138,508,060)
Fair Value, Inputs, Level 1 [Member] | Short-Term Investments [Member] |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |
Securities, fair value | 2,617,817,593 | 2,468,495,664
Fair Value, Inputs, Level 1 [Member] | Exchange-Traded Futures Contracts [Member] | United States [Member] |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |
Securities, fair value | (96,981,140) | (138,508,060)
Fair Value, Inputs, Level 2 [Member] | Short-Term Investments [Member] |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |
Securities, fair value | 0 | 0
Fair Value, Inputs, Level 2 [Member] | Exchange-Traded Futures Contracts [Member] | United States [Member] |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |
Securities, fair value | 0 | 0
Fair Value, Inputs, Level 3 [Member] | Short-Term Investments [Member] |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |
Securities, fair value | 0 | 0
Fair Value, Inputs, Level 3 [Member] | Exchange-Traded Futures Contracts [Member] | United States [Member] |  |
Schedule of Trading Securities and Other Trading Assets [Line Items] |  |
Securities, fair value | $ 0 | $ 0

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- Definition Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Trading Securities -URI http://asc.fasb.org/extlink&oid=6526789 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 35 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=27723805&loc=d3e24584-111560 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=51813488&loc=d3e22054-111558 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Available-for-Sale Securities -URI http://asc.fasb.org/extlink&oid=6505594 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 03 -Paragraph 1 -Subparagraph a, f, g -Article 7 + Details
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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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