Condensed Consolidated Schedule of Investments (Detail) (USD $)	Jun. 30, 2012	Dec. 31, 2011
Fixed Income Securities
Schedule of Investments [Line Items]
Fair value	$ 19,952,245	$ 21,870,890
Fixed Income Securities | Commercial Paper
Schedule of Investments [Line Items]
Percentage of Net Assets	12.69%	9.00%
Fair value	3,545,497	3,142,811
Fixed Income Securities | Commercial Paper | South Korea | Financials
Schedule of Investments [Line Items]
Percentage of Net Assets	3.57%
Fair value	999,017
Fixed Income Securities | Commercial Paper | Australia | Financials
Schedule of Investments [Line Items]
Percentage of Net Assets	4.65%
Fair value	1,298,353
Fixed Income Securities | Commercial Paper | Chile | Financials
Schedule of Investments [Line Items]
Percentage of Net Assets	4.47%
Fair value	1,248,127
Fixed Income Securities | Commercial Paper | United States | Financials
Schedule of Investments [Line Items]
Percentage of Net Assets		5.44%
Fair value		1,899,873
Fixed Income Securities | Commercial Paper | United States | Energy
Schedule of Investments [Line Items]
Percentage of Net Assets		3.56%
Fair value		1,242,938
Fixed Income Securities | Corporate Bonds
Schedule of Investments [Line Items]
Percentage of Net Assets	23.98%	23.53%
Fair value	6,703,371	8,224,432
Fixed Income Securities | Corporate Bonds | Australia | Financials
Schedule of Investments [Line Items]
Percentage of Net Assets	15.75%
Fair value	4,402,115
Fixed Income Securities | Corporate Bonds | United States | Financials
Schedule of Investments [Line Items]
Percentage of Net Assets	8.23%	19.22%
Fair value	2,301,256	6,717,547
Fixed Income Securities | Corporate Bonds | Great Britain | Energy
Schedule of Investments [Line Items]
Percentage of Net Assets		4.31%
Fair value		1,506,885
Fixed Income Securities | Government Agencies | United States
Schedule of Investments [Line Items]
Percentage of Net Assets	34.70%	30.04%
Fair value	9,699,284	10,498,215
Fixed Income Securities | Short-Term Investment Funds | United States
Schedule of Investments [Line Items]
Percentage of Net Assets	0.01%	0.02%
Fair value	4,093	5,432
Long Positions, Futures Positions
Schedule of Investments [Line Items]
Fair value	45,727	(373,540)
Long Positions, Futures Positions | Energy
Schedule of Investments [Line Items]
Percentage of Net Assets	0.06%	(0.34%)
Fair value	15,729	(119,410)
Long Positions, Futures Positions | Agriculture
Schedule of Investments [Line Items]
Percentage of Net Assets	0.31%	0.01%
Fair value	85,341	3,573
Long Positions, Futures Positions | Currency
Schedule of Investments [Line Items]
Percentage of Net Assets	(0.01%)	0.03%
Fair value	(2,638)	9,244
Long Positions, Futures Positions | Indices
Schedule of Investments [Line Items]
Percentage of Net Assets	0.08%	0.05%
Fair value	22,188	17,851
Long Positions, Futures Positions | Interest Rates
Schedule of Investments [Line Items]
Percentage of Net Assets	(0.05%)	0.40%
Fair value	(12,962)	139,768
Long Positions, Futures Positions | Metals
Schedule of Investments [Line Items]
Percentage of Net Assets	(0.22%)	(0.23%)
Fair value	(61,931)	(80,138)
Long Positions, Futures Positions | Forward Positions | Currency
Schedule of Investments [Line Items]
Percentage of Net Assets		(0.99%)
Fair value		(344,428)
Long Positions, Futures Positions | Put Option
Schedule of Investments [Line Items]
Fair value		22,525
Long Positions, Futures Positions | Put Option | Currency
Schedule of Investments [Line Items]
Percentage of Net Assets		0.06%
Fair value		22,525
Short Positions, Futures Positions
Schedule of Investments [Line Items]
Fair value	(393,725)	737,487
Short Positions, Futures Positions | Energy
Schedule of Investments [Line Items]
Percentage of Net Assets	(0.21%)	0.64%
Fair value	(59,466)	225,038
Short Positions, Futures Positions | Agriculture
Schedule of Investments [Line Items]
Percentage of Net Assets	(0.42%)	0.02%
Fair value	(116,067)	6,835
Short Positions, Futures Positions | Currency
Schedule of Investments [Line Items]
Percentage of Net Assets	(0.36%)	(0.02%)
Fair value	(99,739)	(5,365)
Short Positions, Futures Positions | Indices
Schedule of Investments [Line Items]
Percentage of Net Assets	(0.79%)	(0.13%)
Fair value	(220,361)	(47,027)
Short Positions, Futures Positions | Interest Rates
Schedule of Investments [Line Items]
Percentage of Net Assets	0.00%	(0.03%)
Fair value	398	(10,045)
Short Positions, Futures Positions | Metals
Schedule of Investments [Line Items]
Percentage of Net Assets	0.36%	0.21%
Fair value	101,510	72,320
Short Positions, Futures Positions | Forward Positions | Currency
Schedule of Investments [Line Items]
Percentage of Net Assets		1.42%
Fair value		495,731
Short Positions, Futures Positions | Put Option
Schedule of Investments [Line Items]
Fair value	(34,540)	(1,006)
Short Positions, Futures Positions | Put Option | Currency
Schedule of Investments [Line Items]
Percentage of Net Assets		0.00%
Fair value		(1,006)
Short Positions, Futures Positions | Put Option | Indices
Schedule of Investments [Line Items]
Percentage of Net Assets	(0.12%)
Fair value	(34,540)
Total unrealized gain (loss) on open contracts
Schedule of Investments [Line Items]
Fair value	$ (347,998)	$ 363,947