Derivative Instruments and Hedging Activities (Details) (USD $)	Jun. 30, 2012	Dec. 31, 2011
Fair value of all derivative instruments held by the Fund
Total of Asset Derivatives	$ 2,788,740	$ 0
Number of Contracts [Member]
Fair value of all derivative instruments held by the Fund
Total of Liability Derivatives	(2,337,232)	(5,473,287)
Number of Contracts [Member] | Futures Contracts [Member]
Fair value of all derivative instruments held by the Fund
Derivative asset, fair value, gross asset	6,271,039
Derivative asset, fair value, gross liability	(3,482,299)
Derivative liability, fair value, gross asset		2,849,485
Derivative liability, fair value, gross liability		(7,771,315)
Total of Asset Derivatives		0
Total of Liability Derivatives	0
Number of Contracts [Member] | Options [Member]
Fair value of all derivative instruments held by the Fund
Total of Liability Derivatives	$ (2,337,232)	$ (551,457)