Schedule of Investments (Unaudited) - Treasury Bills and Money Market Fund - USD ($) | 3 Months Ended | 12 Months Ended |
Mar. 31, 2019 | Dec. 31, 2018 |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | | 99.47% | | 103.49% | |
United States Treasury Obligations, Value | | $ 273,523,483 | | $ 409,384,745 | |
Affiliated Investments, value | | 99,259,143 | | 102,216,801 | |
Investments in Securities, Value | | 372,782,626 | | 511,601,546 | |
Investments in Securities, Cost | | $ 372,926,198 | | $ 511,790,491 | |
Affiliated Investments [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | | 26.49% | | 20.68% | |
Affiliated Investments, value | | $ 99,259,143 | | $ 102,216,801 | |
Affiliated Investments, at Cost | | $ 99,409,937 | | $ 102,405,445 | |
U.S. Treasury Bills, 2.465% due April 4, 2019 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | 14.14% | | 10.65% | |
United States Treasury Obligations, Value | [1] | $ 52,989,593 | | $ 52,672,055 | |
United States Treasury Obligations, Principal Value | [1] | $ 53,000,000 | | $ 53,000,000 | |
Investment Interest Rate | [1] | 2.465% | | 2.465% | |
Investment Maturity Date | [1] | Apr. 4, 2019 | | Apr. 4, 2019 | |
U.S. Treasury Bills, 2.470% due April 23, 2019 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | 27.71% | | | |
United States Treasury Obligations, Value | [1] | $ 103,848,463 | | | |
United States Treasury Obligations, Principal Value | [1] | $ 104,000,000 | | | |
Investment Interest Rate | [1] | 2.47% | | | |
Investment Maturity Date | [1] | Apr. 23, 2019 | | | |
U.S. Treasury Bills, 2.375% due May 2, 2019 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1],[2] | 26.63% | | | |
United States Treasury Obligations, Value | [1],[2] | $ 99,798,177 | | | |
United States Treasury Obligations, Principal Value | [1],[2] | $ 100,000,000 | | | |
Investment Interest Rate | [1],[2] | 2.375% | | | |
Investment Maturity Date | [1],[2] | May 2, 2019 | | | |
Restricted for maintenance margin | | $ 10,677,530 | | | |
U.S. Treasury Bills, 2.470% due July 11, 2019 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | 4.50% | | | |
United States Treasury Obligations, Value | [1] | $ 16,887,250 | | | |
United States Treasury Obligations, Principal Value | [1] | $ 17,000,000 | | | |
Investment Interest Rate | [1] | 2.47% | | | |
Investment Maturity Date | [1] | Jul. 11, 2019 | | | |
United States Treasury Obligations [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | | 72.98% | | 82.81% | |
United States Treasury Obligations, Value | | $ 273,523,483 | | $ 409,384,745 | |
Investments in Securities, Cost | | $ 273,516,261 | | $ 409,385,046 | |
Exchange-Traded Fund [Member] | Affiliated Investments [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [3] | 21.31% | | 16.15% | |
Affiliated Investments, value | [3] | $ 79,855,930 | | $ 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 | | 5.18% | [4] | 4.53% | [5] |
Affiliated Investments, value | | $ 19,403,213 | [4] | $ 22,398,721 | [5] |
Affiliated Investments, Shares | | 19,403,213 | [4] | 22,398,721 | [5] |
Investment Interest Rate | | 2.33% | [4] | 2.30% | [5] |
Investments in Securities, Cost | | $ 19,403,213 | [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. 3, 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, 2.430% 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 2, 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 $10,677,530 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 March 31, 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. | |