Derivative Instruments (Details 3) (USD $)	3 Months Ended	6 Months Ended
Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Net gain (loss) from futures and forward trading
Total realized and changed in unrealized net gain (loss) from futures and forward trading	$ (17,513,180)	$ 26,777,604	$ (6,532,821)	$ 32,929,604
Futures and Forward Trading
Net gain (loss) from futures and forward trading
Realized	(15,812,188)	27,684,339	(7,305,220)	41,476,447
Change in unrealized	(1,700,992)	(906,735)	772,399	(8,546,843)
Total realized and changed in unrealized net gain (loss) from futures and forward trading	$ (17,513,180)	$ 26,777,604	$ (6,532,821)	$ 32,929,604

The difference between the book value and the sale price of options, swaps, futures, forward contracts, and other derivative instruments. This element refers to the gain (loss) included in earnings.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 28

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-04.13(h))

-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

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