Schedule of Investments - Treasury Bills and Money Market Fund - USD ($)		12 Months Ended
		Dec. 31, 2018		Dec. 31, 2017
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity		103.98%		95.33%
United States Treasury Obligations, Value		$ 1,614,425,920		$ 1,839,039,728
Affiliated Investments, Value		395,084,923		317,746,227
Investments in Securities, Value		2,009,510,843		2,156,785,955
Investments in Securities, Cost		$ 2,009,415,674		$ 2,157,140,963
Affiliated Investments [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity		20.44%		14.04%
Affiliated Investments, Value		$ 395,084,923		$ 317,746,227
Affiliated Investments, at Cost		$ 394,929,293		$ 317,993,905
U.S. Treasury Bills, 2.175% due January 3, 2019 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]	4.87%
United States Treasury Obligations, Value	[1]	$ 93,994,138
United States Treasury Obligations, Principal Value	[1]	$ 94,000,000
Investment Interest Rate		2.175%
Investment Maturity Date		Jan. 03, 2019
U.S. Treasury Bills, 2.370% due February 28, 2019 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]	33.35%
United States Treasury Obligations, Value	[1]	$ 644,565,727
United States Treasury Obligations, Principal Value	[1]	$ 647,000,000
Investment Interest Rate		2.37%
Investment Maturity Date		Feb. 28, 2019
U.S. Treasury Bills, 2.465% due April 4, 2019 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]	26.38%
United States Treasury Obligations, Value	[1]	$ 509,825,741
United States Treasury Obligations, Principal Value	[1]	$ 513,000,000
Investment Interest Rate		2.465%
Investment Maturity Date		Apr. 04, 2019
U.S. Treasury Bills, 2.430% due May 2, 2019 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1],[2]	18.94%
United States Treasury Obligations, Value	[1],[2]	$ 366,040,314
United States Treasury Obligations, Principal Value	[1],[2]	$ 369,000,000
Investment Interest Rate	[2]	2.43%
Investment Maturity Date	[2]	May 02, 2019
Restricted for maintenance margin		$ 255,836,800
United States Treasury Obligations [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]	83.54%		81.29%
United States Treasury Obligations, Value	[1]	$ 1,614,425,920		$ 1,839,039,728
Investments in Securities, Cost		$ 1,614,486,381		$ 1,839,147,058
Exchange-Traded Fund [Member] | Affiliated Investments [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[3]	12.94%		11.04%
Affiliated Investments, Value	[3]	$ 250,145,856		$ 249,742,548
Affiliated Investments, Shares	[3]	2,372,400		2,372,400
Affiliated Investments, at Cost		$ 249,990,226		$ 249,990,226
Money Market Mutual Fund - Invesco Premier U.S. Government Money Portfolio - Institutional Class [Member] | Affiliated Investments [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity		7.50%	[4]	3.00%	[5]
Affiliated Investments, Value		$ 144,939,067	[4]	$ 68,003,679	[5]
Affiliated Investments, Shares		144,939,067	[4]	68,003,679	[5]
Investment Interest Rate		2.30%		1.15%
Affiliated Investments, at Cost		$ 144,939,067		$ 68,003,679
U.S. Treasury Bills, 1.180% due January 4, 2018 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]			13.30%
United States Treasury Obligations, Value	[1]			$ 300,981,124
United States Treasury Obligations, Principal Value	[1]			$ 301,000,000
Investment Interest Rate				1.18%
Investment Maturity Date				Jan. 04, 2018
U.S. Treasury Bills, 1.245% due January 18, 2018 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]			12.77%
United States Treasury Obligations, Value	[1]			$ 288,841,533
United States Treasury Obligations, Principal Value	[1]			$ 289,000,000
Investment Interest Rate				1.245%
Investment Maturity Date				Jan. 18, 2018
U.S. Treasury Bills, 1.285% due February 22, 2018 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]			26.78%
United States Treasury Obligations, Value	[1]			$ 605,916,505
United States Treasury Obligations, Principal Value	[1]			$ 607,000,000
Investment Interest Rate				1.285%
Investment Maturity Date				Feb. 22, 2018
U.S. Treasury Bills, 1.285% due March 1, 2018 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1],[6]			24.53%
United States Treasury Obligations, Value	[1],[6]			$ 554,864,604
United States Treasury Obligations, Principal Value	[1],[6]			$ 556,000,000
Investment Interest Rate	[6]			1.285%
Investment Maturity Date	[6]			Mar. 01, 2018
Restricted for maintenance margin				$ 199,580,000
U.S. Treasury Bills, 1.450% due June 7, 2018 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]			3.91%
United States Treasury Obligations, Value	[1]			$ 88,435,962
United States Treasury Obligations, Principal Value	[1]			$ 89,000,000
Investment Interest Rate				1.45%
Investment Maturity Date				Jun. 07, 2018

[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 $255,836,800 are on deposit with the Commodity Broker and held as maintenance margin for open futures contracts.

[3] Affiliated company. The security and the Fund are affiliated by having the same investment adviser. See Note 8.

[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, 2018.

[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, 2017.

[6] United States Treasury Obligations of $199,580,000 are on deposit with the Commodity Broker and held as maintenance margin for open futures contracts.