Schedule of Investments (Unaudited) - Treasury Bills (Parenthetical) - USD ($)		6 Months Ended		12 Months Ended
		Jun. 30, 2016		Dec. 31, 2015
U.S. Treasury Bills, 0.19% due July 07, 2016 [Member]
Schedule of Investments [Line Items]
Investment Interest Rate		0.19%
Investment Maturity Date		Jul. 07, 2016
U.S. Treasury Bills, 0.25% due July 21, 2016 [Member]
Schedule of Investments [Line Items]
Investment Interest Rate		0.25%
Investment Maturity Date		Jul. 21, 2016
U.S. Treasury Bills, 0.26% due July 28, 2016 [Member]
Schedule of Investments [Line Items]
Investment Interest Rate		0.26%
Investment Maturity Date		Jul. 28, 2016
U.S. Treasury Bills, 0.34% due September 01, 2016 [Member]
Schedule of Investments [Line Items]
Investment Interest Rate	[1]	0.34%
Investment Maturity Date	[1]	Sep. 01, 2016
Restricted for maintenance margin	[1]	$ 22,991,107
United States Treasury Obligations [Member]
Schedule of Investments [Line Items]
United States Treasury Obligations, cost		$ 789,863,093	[2]	$ 1,077,885,299	[3]
U.S. Treasury Bills, 0.235% due January 7, 2016 [Member]
Schedule of Investments [Line Items]
Investment Interest Rate				0.235%
Investment Maturity Date				Jan. 07, 2016
U.S. Treasury Bills, 0.205% due January 14, 2016 [Member]
Schedule of Investments [Line Items]
Investment Interest Rate				0.205%
Investment Maturity Date				Jan. 14, 2016
U.S. Treasury Bills, 0.195% due January 21, 2016 [Member]
Schedule of Investments [Line Items]
Investment Interest Rate	[4]			0.195%
Investment Maturity Date	[4]			Jan. 21, 2016
Restricted for maintenance margin	[4]			$ 34,998,099
U.S. Treasury Bills, 0.170% due January 28, 2016 [Member]
Schedule of Investments [Line Items]
Investment Interest Rate				0.17%
Investment Maturity Date				Jan. 28, 2016
U.S. Treasury Bills, 0.200% due February 4, 2016 [Member]
Schedule of Investments [Line Items]
Investment Interest Rate				0.20%
Investment Maturity Date				Feb. 04, 2016
U.S. Treasury Bills, 0.135% due February 11, 2016 [Member]
Schedule of Investments [Line Items]
Investment Interest Rate				0.135%
Investment Maturity Date				Feb. 11, 2016
U.S. Treasury Bills, 0.145% due February 18, 2016 [Member]
Schedule of Investments [Line Items]
Investment Interest Rate				0.145%
Investment Maturity Date				Feb. 18, 2016
U.S. Treasury Bills, 0.140% due February 25, 2016 [Member]
Schedule of Investments [Line Items]
Investment Interest Rate				0.14%
Investment Maturity Date				Feb. 25, 2016
U.S. Treasury Bills, 0.215% due March 3, 2016 [Member]
Schedule of Investments [Line Items]
Investment Interest Rate				0.215%
Investment Maturity Date				Mar. 03, 2016
U.S. Treasury Bills, 0.280% due March 10, 2016 [Member]
Schedule of Investments [Line Items]
Investment Interest Rate				0.28%
Investment Maturity Date				Mar. 10, 2016

[1] United States Treasury Obligations of $22,991,107 are on deposit with the Commodity Broker and held as maintenance margin for open futures contracts.

[2] Security may be traded on a discount basis. The interest rate shown represents the discount rate at the most recent auction date of the security prior to period end.

[3] Security may be traded on a discount basis. The interest rate shown represents the discount rate at the most recent auction date of the security prior to year end.

[4] United States Treasury Obligations of $34,998,099 are on deposit with the Commodity Broker and held as maintenance margin for open futures contracts.