Subsequent Events - Additional Information (Detail) (Portfolio Allocation Agreement)	1 Months Ended
	Jul. 01, 2012
Liberty Funds Group
Subsequent Event [Line Items]
Allocation percent of the portfolio	21.00%
Nuwave Investment Management, Llc
Subsequent Event [Line Items]
Allocation percent of the portfolio	22.00%
Abraham Trading Corp
Subsequent Event [Line Items]
Allocation percent of the portfolio	16.67%
Aventis Asset Management
Subsequent Event [Line Items]
Allocation percent of the portfolio	22.00%
Hyman Beck and Company, Inc | Maximum
Subsequent Event [Line Items]
Allocation percent of the portfolio	10.00%
John W. Henry and Company, Inc | Maximum
Subsequent Event [Line Items]
Allocation percent of the portfolio	10.00%