Schedule of Investments - Futures Contracts - Futures [Member]		12 Months Ended
		Dec. 31, 2016 USD ($) Contract	Dec. 31, 2015 USD ($) Contract
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity		0.24%	0.80%
Unrealized Appreciation/ (Depreciation)	[1]	$ 1,988,810	$ 9,076,613
Notional Value		$ 845,905,220	$ 1,133,790,090
United States of America, Dollars | ICE FUTURES U.S. [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity		0.24%	0.80%
Unrealized Appreciation/ (Depreciation)	[1]	$ 1,988,810	$ 9,076,613
Notional Value		$ 845,905,220	$ 1,133,790,090
Number of Contracts | Contract		8,270	11,482
Maturity Date		Mar. 13, 2017	Mar. 14, 2016

[1] Unrealized appreciation/(depreciation) is presented above, net by contract.