Schedule of Investments - Treasury Bills and Money Market Fund - USD ($)		12 Months Ended
		Dec. 31, 2016		Dec. 31, 2015
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity		99.78%
Value		$ 702,215,941		$ 626,952,136
Affiliated investments, at value and cost		19,456,137
Total Investments		721,672,078		626,952,136
Investments, cost		$ 721,689,108		$ 626,932,029
U.S. Treasury Bills, 0.490% due January 19, 2017 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]	17.56%
Value	[1]	$ 126,977,013
Principal Value	[1]	$ 127,000,000
Investment Interest Rate	[1]	0.49%
Investment Maturity Date	[1]	Jan. 19, 2017
U.S. Treasury Bills, 0.485% due January 26, 2017 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]	9.81%
Value	[1]	$ 70,981,327
Principal Value	[1]	$ 71,000,000
Investment Interest Rate	[1]	0.485%
Investment Maturity Date	[1]	Jan. 26, 2017
U.S. Treasury Bills, 0.490% due March 2, 2017 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]	17.13%
Value	[1]	$ 123,905,140
Principal Value	[1]	$ 124,000,000
Investment Interest Rate	[1]	0.49%
Investment Maturity Date	[1]	Mar. 02, 2017
U.S. Treasury Bills, 0.530% due April 6, 2017 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1],[2]	32.03%
Value	[1],[2]	$ 231,687,264
Principal Value	[1],[2]	$ 232,000,000
Investment Interest Rate	[1],[2]	0.53%
Investment Maturity Date	[1],[2]	Apr. 06, 2017
Restricted for maintenance margin		$ 104,853,000
U.S. Treasury Bills, 0.625% due May 18, 2017 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]	20.56%
Value	[1]	$ 148,665,197
Principal Value	[1]	$ 149,000,000
Investment Interest Rate	[1]	0.625%
Investment Maturity Date	[1]	May 18, 2017
United States Treasury Obligations [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity		97.09%	[1]	93.04%	[3]
Value		$ 702,215,941	[1]	$ 626,952,136	[3]
Investments, cost		$ 702,232,971		$ 626,932,029	[3],[4]
Money Market Mutual Fund [Member] | Premier U.S. Government Money Portfolio - Institutional Class [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[5]	2.69%
Affiliated investments, at value and cost	[5]	$ 19,456,137
Shares	[5]	19,456,137
Investment Interest Rate	[1],[5]	0.41%
Investments, cost	[5]	$ 19,456,137
U.S. Treasury Bills, 0.235% due January 7, 2016 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[3]			8.90%
Value	[3]			$ 59,999,760
Principal Value	[3]			$ 60,000,000
Investment Interest Rate	[3]			0.235%
Investment Maturity Date	[3]			Jan. 07, 2016
U.S. Treasury Bills, 0.205% due January 14, 2016 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[3]			20.78%
Value	[3]			$ 139,996,080
Principal Value	[3]			$ 140,000,000
Investment Interest Rate	[3]			0.205%
Investment Maturity Date	[3]			Jan. 14, 2016
U.S. Treasury Bills, 0.195% due January 21, 2016 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[3],[4]			20.77%
Value	[3],[4]			$ 139,994,260
Principal Value	[3],[4]			$ 140,000,000
Investment Interest Rate	[3],[4]			0.195%
Investment Maturity Date	[3],[4]			Jan. 21, 2016
Restricted for maintenance margin				$ 94,990,500
U.S. Treasury Bills, 0.170% due January 28, 2016 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[3]			14.10%
Value	[3]			$ 94,992,210
Principal Value	[3]			$ 95,000,000
Investment Interest Rate	[3]			0.17%
Investment Maturity Date	[3]			Jan. 28, 2016
U.S. Treasury Bills, 0.200% due February 4, 2016 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[3]			1.19%
Value	[3]			$ 7,999,376
Principal Value	[3]			$ 8,000,000
Investment Interest Rate	[3]			0.20%
Investment Maturity Date	[3]			Feb. 04, 2016
U.S. Treasury Bills, 0.135% due February 11, 2016 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[3]			12.91%
Value	[3]			$ 86,988,516
Principal Value	[3]			$ 87,000,000
Investment Interest Rate	[3]			0.135%
Investment Maturity Date	[3]			Feb. 11, 2016
U.S. Treasury Bills, 0.140% due February 25, 2016 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[3]			2.52%
Value	[3]			$ 16,998,334
Principal Value	[3]			$ 17,000,000
Investment Interest Rate	[3]			0.14%
Investment Maturity Date	[3]			Feb. 25, 2016
U.S. Treasury Bills, 0.280% due March 10, 2016 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[3]			11.87%
Value	[3]			$ 79,983,600
Principal Value	[3]			$ 80,000,000
Investment Interest Rate	[3]			0.28%
Investment Maturity Date	[3]			Mar. 10, 2016

[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 $104,853,000 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] United States Treasury Obligations of $94,990,500 are on deposit with the Commodity Broker and held as maintenance margin for open futures contracts.

[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.