Fair Value of Financial Instruments (Valuation of Securities Using Fair Value Hierarchy) (Details) (USD $)	Jun. 30, 2013	Dec. 31, 2012
Schedule of Trading Securities and Other Trading Assets [Line Items]
Securities, fair value	$ 66,155,111	$ 92,755,785
Exchange-Traded Futures Contracts [Member] \| United States [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Securities, fair value	445,310	1,556,910
Fair Value, Inputs, Level 1 [Member] \| Short-Term Investments [Member]
Schedule of Trading Securities and Other Trading Assets [Line Items]
Securities, fair value	66,155,111	92,755,785
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	$ 445,310	$ 1,556,910

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

Reference 1: 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 2: 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 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=28360136&loc=d3e22054-111558

Reference 4: 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

Reference 5: 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

Name:	us-gaap_InvestmentsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant