Schedule of Investments (Unaudited) - Treasury Bills and Money Market Fund - USD ($)		6 Months Ended		12 Months Ended
		Jun. 30, 2019		Dec. 31, 2018
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity		101.97%		103.49%
United States Treasury Obligations, Value		$ 226,342,665		$ 409,384,745
Affiliated Investments, value		101,954,188		102,216,801
Investments in Securities, Value		328,296,853		511,601,546
Investments in Securities, Cost		$ 328,266,160		$ 511,790,491
Affiliated Investments [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity		31.67%		20.68%
Affiliated Investments, value		$ 101,954,188		$ 102,216,801
Affiliated Investments, at Cost		$ 102,025,497		$ 102,405,445
U.S. Treasury Bills, 2.385% due August 1, 2019 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]	9.95%
United States Treasury Obligations, Value	[1]	$ 32,044,579
United States Treasury Obligations, Principal Value	[1]	$ 32,100,000
Investment Interest Rate	[1]	2.385%
Investment Maturity Date	[1]	Aug. 01, 2019
U.S. Treasury Bills, 2.360% due August 15, 2019 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]	32.53%
United States Treasury Obligations, Value	[1]	$ 104,726,015
United States Treasury Obligations, Principal Value	[1]	$ 105,000,000
Investment Interest Rate	[1]	2.36%
Investment Maturity Date	[1]	Aug. 15, 2019
U.S. Treasury Bills, 2.240% due September 12, 2019 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1],[2]	18.25%
United States Treasury Obligations, Value	[1],[2]	$ 58,753,843
United States Treasury Obligations, Principal Value	[1],[2]	$ 59,000,000
Investment Interest Rate	[1],[2]	2.24%
Investment Maturity Date	[1],[2]	Sep. 12, 2019
Restricted for maintenance margin		$ 10,655,060
U.S. Treasury Bills, 2.210% due October 10, 2019 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]	9.57%
United States Treasury Obligations, Value	[1]	$ 30,818,228
United States Treasury Obligations, Principal Value	[1]	$ 31,000,000
Investment Interest Rate	[1]	2.21%
Investment Maturity Date	[1]	Oct. 10, 2019
United States Treasury Obligations [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity		70.30%		82.81%
United States Treasury Obligations, Value		$ 226,342,665		$ 409,384,745
Investments in Securities, Cost		$ 226,240,663		$ 409,385,046
Exchange-Traded Fund [Member] | Affiliated Investments [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[3]	24.83%		16.15%
Affiliated Investments, value	[3]	$ 79,935,415		$ 79,818,080
Affiliated Investments, Shares	[3]	757,000		757,000
Affiliated Investments, at Cost	[3]	$ 80,006,724		$ 80,006,724
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		6.84%	[4]	4.53%	[5]
Affiliated Investments, value		$ 22,018,773	[4]	$ 22,398,721	[5]
Affiliated Investments, Shares		22,018,773	[4]	22,398,721	[5]
Investment Interest Rate		2.26%	[4]	2.30%	[5]
Investments in Securities, Cost		$ 22,018,773	[4]	$ 22,398,721	[5]
U.S. Treasury Bills, 2.175% due January 3, 2019 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]			24.68%
United States Treasury Obligations, Value	[1]			$ 121,992,392
United States Treasury Obligations, Principal Value	[1]			$ 122,000,000
Investment Interest Rate	[1]			2.175%
Investment Maturity Date	[1]			Jan. 03, 2019
U.S. Treasury Bills, 2.370% due February 28, 2019 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]			29.02%
United States Treasury Obligations, Value	[1]			$ 143,458,214
United States Treasury Obligations, Principal Value	[1]			$ 144,000,000
Investment Interest Rate	[1]			2.37%
Investment Maturity Date	[1]			Feb. 28, 2019
U.S. Treasury Bills, 2.465% due April 4, 2019 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1]			10.65%
United States Treasury Obligations, Value	[1]			$ 52,672,055
United States Treasury Obligations, Principal Value	[1]			$ 53,000,000
Investment Interest Rate	[1]			2.465%
Investment Maturity Date	[1]			Apr. 04, 2019
U.S. Treasury Bills, 2.430% due May 2, 2019 [Member]
Schedule of Investments [Line Items]
Percentage of Shareholders' Equity	[1],[6]			18.46%
United States Treasury Obligations, Value	[1],[6]			$ 91,262,084
United States Treasury Obligations, Principal Value	[1],[6]			$ 92,000,000
Investment Interest Rate	[1],[6]			2.43%
Investment Maturity Date	[1],[6]			May 02, 2019
Restricted for maintenance margin				$ 10,614,400

[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 $10,655,060 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 June 30, 2019.

[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, 2018.

[6] United States Treasury Obligations of $10,614,400 are on deposit with the Commodity Broker and held as maintenance margin for open futures contracts.