Schedule of Investments (Unaudited) - Treasury Bills and Money Market Fund - USD ($)		6 Months Ended		12 Months Ended
		Jun. 30, 2017		Dec. 31, 2016
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity		99.74%		99.16%
Value		$ 40,963,943		$ 30,970,236
Affiliated investments, at value		2,504,620		1,502,575
Total Investments		43,468,563		32,472,811
Investments, cost		$ 43,465,491		$ 32,473,872
U.S. Treasury Bills, 0.840% due July 6, 2017 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]	29.83%
Value	[1]	$ 12,999,181
Principal Value	[1]	$ 13,000,000
Investment Interest Rate	[1]	0.84%
Investment Maturity Date	[1]	Jul. 06, 2017
U.S. Treasury Bills, 0.890% due July 27, 2017 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1],[2]	18.34%
Value	[1],[2]	$ 7,995,656
Principal Value	[1],[2]	$ 8,000,000
Investment Interest Rate	[1],[2]	0.89%
Investment Maturity Date	[1],[2]	Jul. 27, 2017
Restricted for maintenance margin		$ 2,998,200
U.S. Treasury Bills, 0.960% due August 31, 2017 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]	41.24%
Value	[1]	$ 17,972,928
Principal Value	[1]	$ 18,000,000
Investment Interest Rate	[1]	0.96%
Investment Maturity Date	[1]	Aug. 31, 2017
U.S. Treasury Bills, 0.990% due September 14, 2017 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]	4.58%
Value	[1]	$ 1,996,178
Principal Value	[1]	$ 2,000,000
Investment Interest Rate	[1]	0.99%
Investment Maturity Date	[1]	Sep. 14, 2017
United States Treasury Obligations [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity		93.99%	[1]	94.57%	[3]
Value		$ 40,963,943	[1]	$ 30,970,236	[3]
Investments, cost		$ 40,960,871	[1]	$ 30,971,297	[3]
Money Market Mutual Fund - Premier U.S. Government Money Portfolio - Institutional Class [Member] | Affiliated Investments [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity		5.75%	[4]	4.59%	[5]
Affiliated investments, at value		$ 2,504,620	[4]	$ 1,502,575	[5]
Shares		2,504,620	[4]	1,502,575	[5]
Investment Interest Rate		0.86%	[4]	0.41%	[5]
Investments, cost		$ 2,504,620	[4]	$ 1,502,575	[5]
U.S. Treasury Bills, 0.485% due January 26, 2017 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[3]			18.32%
Value	[3]			$ 5,998,422
Principal Value	[3]			$ 6,000,000
Investment Interest Rate	[3]			0.485%
Investment Maturity Date	[3]			Jan. 26, 2017
U.S. Treasury Bills, 0.490% due March 2, 2017 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[3]			33.56%
Value	[3]			$ 10,991,585
Principal Value	[3]			$ 11,000,000
Investment Interest Rate	[3]			0.49%
Investment Maturity Date	[3]			Mar. 02, 2017
U.S. Treasury Bills, 0.530% due April 6, 2017 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[3],[6]			39.64%
Value	[3],[6]			$ 12,982,476
Principal Value	[3],[6]			$ 13,000,000
Investment Interest Rate	[3],[6]			0.53%
Investment Maturity Date	[3],[6]			Apr. 06, 2017
Restricted for maintenance margin				$ 4,293,980
U.S. Treasury Bills, 0.625% due May 18, 2017 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[3]			3.05%
Value	[3]			$ 997,753
Principal Value	[3]			$ 1,000,000
Investment Interest Rate	[3]			0.625%
Investment Maturity Date	[3]			May 18, 2017

[1] 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.

[2] United States Treasury Obligations of $2,998,200 are on deposit with the Commodity Broker and held as maintenance margin for open futures contracts.

[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] The security and the Fund are advised by wholly-owned subsidiaries of Invesco Ltd. and are therefore considered to be affiliated. The rate shown is the 7-day SEC standardized yield as of June 30, 2017.

[5] The security and the Fund are advised by wholly-owned subsidiaries of Invesco Ltd. and are therefore considered to be affiliated. The rate shown is the 7-day SEC standardized yield as of December 31, 2016.

[6] United States Treasury Obligations of $4,293,980 are on deposit with the Commodity Broker and held as maintenance margin for open futures contracts.