Summary of Significant Accounting Policies (Details Textual)	6 Months Ended	12 Months Ended
	Jun. 30, 2012 Contract	Dec. 31, 2011 Contract
Summary of Significant Accounting Policies (Additional Textual) [Abstract]
Percentage of Fund's assets committed to secure Fund's futures and forward contract positions	15.00%
Period of assets invested in cash equivalents	not exceeding one year
Maturity of prices of fixed-income securities	one year or less
Period of assets invested in cash or treasury bills	less than one year
Futures Contracts [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Average number of contracts outstanding	3,559	3,636
Call option [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Average number of contracts outstanding	1,675	1,712
Forward contracts [Member]
Summary of Significant Accounting Policies (Textual) [Abstract]
Average number of contracts outstanding	0	0