Schedule of Investments (Unaudited) - Treasury Bills and Money Market Fund - USD ($)		3 Months Ended		12 Months Ended
		Mar. 31, 2017		Dec. 31, 2016
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity		97.95%		99.12%
Value		$ 1,848,831,568		$ 2,403,838,023
Affiliated investments, at value		346,000,956		131,029,805
Total Investments		2,194,832,524		2,534,867,828
Investments, cost		$ 2,194,930,838		2,534,934,371
Affiliated Investments [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity		15.44%
Affiliated investments, at value		$ 346,000,956
Affiliated Investments, at Cost		$ 345,916,498		$ 131,029,805
U.S. Treasury Bills, 0.570% due April 6, 2017 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]	14.10%
Value	[1]	$ 315,985,464
Principal Value	[1]	$ 316,000,000
Investment Interest Rate		0.57%
Investment Maturity Date		Apr. 06, 2017
U.S. Treasury Bills, 0.745% due April 27, 2017 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]	34.35%
Value	[1]	$ 769,628,090
Principal Value	[1]	$ 770,000,000
Investment Interest Rate		0.745%
Investment Maturity Date		Apr. 27, 2017
U.S. Treasury Bills, 0.720% due May 18, 2017 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]	16.54%
Value	[1]	$ 370,667,213
Principal Value	[1]	$ 371,000,000
Investment Interest Rate		0.72%
Investment Maturity Date		May 18, 2017
U.S. Treasury Bills, 0.515% due June 1, 2017 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1],[2]	17.52%
Value	[1],[2]	$ 392,550,801
Principal Value	[1],[2]	$ 393,000,000
Investment Interest Rate	[2]	0.515%
Investment Maturity Date	[2]	Jun. 01, 2017
Restricted for maintenance margin		$ 244,706,000
US Treasury Bill Securities [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity		82.51%	[1]	93.99%	[3]
Value		$ 1,848,831,568	[1]	$ 2,403,838,023	[3]
Investments, cost		$ 1,849,014,340		$ 2,403,904,566
Exchange-Traded Fund - PowerShares Treasury Collateral Portfolio [Member] | Affiliated Investments [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[4]	11.16%
Affiliated investments, at value	[4]	$ 250,074,684
Shares	[4]	2,372,400
Affiliated Investments, at Cost		$ 249,990,226
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		4.28%	[5]	5.13%	[6]
Affiliated investments, at value		$ 95,926,272	[5]	$ 131,029,805	[6]
Shares		95,926,272	[5]	131,029,805	[6]
Investment Interest Rate		0.60%		0.41%
Affiliated Investments, at Cost		$ 95,926,272		$ 131,029,805
U.S. Treasury Bills, 0.490% due January 19, 2017 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[3]			21.89%
Value	[3]			$ 559,898,640
Principal Value	[3]			$ 560,000,000
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	[3]			18.61%
Value	[3]			$ 475,874,812
Principal Value	[3]			$ 476,000,000
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	[3]			16.41%
Value	[3]			$ 419,678,700
Principal Value	[3]			$ 420,000,000
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	[3],[7]			22.61%
Value	[3],[7]			$ 578,219,508
Principal Value	[3],[7]			$ 579,000,000
Investment Interest Rate	[7]			0.53%
Investment Maturity Date	[7]			Apr. 06, 2017
Restricted for maintenance margin				$ 244,657,000
U.S. Treasury Bills, 0.625% due May 18, 2017 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[3]			14.47%
Value	[3]			$ 370,166,363
Principal Value	[3]			$ 371,000,000
Investment Interest Rate				0.625%
Investment Maturity Date				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 $244,706,000 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] Affiliated company. The security and the Fund are affiliated by having the same investment adviser. See Note 6.

[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 March 31, 2017.

[6] 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.

[7] United States Treasury Obligations of $244,657,000 are on deposit with the Commodity Broker and held as maintenance margin for open futures contracts.