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		100.48%
Value		$ 846,158,812		$ 1,077,913,905
Affiliated investments, at value and cost		3,786,312
Total Investments		849,945,124		1,077,913,905
Investments, cost		$ 849,976,394		$ 1,077,885,299
U.S. Treasury Bills, 0.490% due January 19, 2017 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity		4.14%
Value		$ 34,993,665
Principal Value		$ 35,000,000
Investment Interest Rate		0.49%
Investment Maturity Date		Jan. 19, 2017
U.S. Treasury Bills, 0.485% due January 26, 2017 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity		26.95%
Value		$ 227,940,036
Principal Value		$ 228,000,000
Investment Interest Rate		0.485%
Investment Maturity Date		Jan. 26, 2017
U.S. Treasury Bills, 0.490% due March 2, 2017 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity		21.26%
Value		$ 179,862,300
Principal Value		$ 180,000,000
Investment Interest Rate		0.49%
Investment Maturity Date		Mar. 02, 2017
U.S. Treasury Bills, 0.530% due April 6, 2017 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]	35.53%
Value	[1]	$ 300,594,252
Principal Value	[1]	$ 301,000,000
Investment Interest Rate	[1]	0.53%
Investment Maturity Date	[1]	Apr. 06, 2017
Restricted for maintenance margin	[1]	$ 18,973,400
U.S. Treasury Bills, 0.625% due May 18, 2017 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity		12.15%
Value		$ 102,768,559
Principal Value		$ 103,000,000
Investment Interest Rate		0.625%
Investment Maturity Date		May 18, 2017
United States Treasury Obligations [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity		100.03%	[2]	95.09%	[3]
Value		$ 846,158,812	[2]	$ 1,077,913,905	[3]
Investments, cost		$ 846,190,082	[2]	$ 1,077,885,299	[3]
Money Market Mutual Fund [Member] | Premier U.S. Government Money Portfolio - Institutional Class, 0.41% [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[4]	0.45%
Affiliated investments, at value and cost	[4]	$ 3,786,312
Shares	[4]	3,786,312
Investment Interest Rate	[4]	0.41%
Investments, cost	[4]	$ 3,786,312
U.S. Treasury Bills, 0.235% due January 7, 2016 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity				12.35%
Value				$ 139,999,440
Principal Value				$ 140,000,000
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]
Percentage of Shareholders' Equity				17.64%
Value				$ 199,994,400
Principal Value				$ 200,000,000
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]
Percentage of Shareholders' Equity	[5]			13.67%
Value	[5]			$ 154,993,645
Principal Value	[5]			$ 155,000,000
Investment Interest Rate	[5]			0.195%
Investment Maturity Date	[5]			Jan. 21, 2016
Restricted for maintenance margin	[5]			$ 34,998,099
U.S. Treasury Bills, 0.170% due January 28, 2016 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity				17.64%
Value				$ 199,983,600
Principal Value				$ 200,000,000
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]
Percentage of Shareholders' Equity				2.03%
Value				$ 22,998,206
Principal Value				$ 23,000,000
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]
Percentage of Shareholders' Equity				8.82%
Value				$ 99,986,800
Principal Value				$ 100,000,000
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]
Percentage of Shareholders' Equity				9.35%
Value				$ 105,986,008
Principal Value				$ 106,000,000
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]
Percentage of Shareholders' Equity				0.27%
Value				$ 2,999,706
Principal Value				$ 3,000,000
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]
Percentage of Shareholders' Equity				5.73%
Value				$ 64,989,730
Principal Value				$ 65,000,000
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]
Percentage of Shareholders' Equity				7.59%
Value				$ 85,982,370
Principal Value				$ 86,000,000
Investment Interest Rate				0.28%
Investment Maturity Date				Mar. 10, 2016

[1] United States Treasury Obligations of $18,973,400 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] 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.

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