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 | | 100.15% | | 101.06% | |
United States Treasury Obligations, Value | | $ 30,909,645 | | $ 27,887,293 | |
Affiliated investments, value | | 2,271,254 | | 1,793,677 | |
Investments in Securities, Value | | 33,180,899 | | 29,680,970 | |
Investments in Securities, cost | | $ 33,179,572 | | $ 29,680,281 | |
U.S. Treasury Bills, 2.465% due April 4, 2019 [Member] | | | | | |
Schedule Of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | 18.11% | | 20.30% | |
United States Treasury Obligations, Value | [1] | $ 5,998,822 | | $ 5,962,874 | |
United States Treasury Obligations, Principal Value | [1] | $ 6,000,000 | | $ 6,000,000 | |
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] | 15.07% | | | |
United States Treasury Obligations, Value | [1] | $ 4,992,715 | | | |
United States Treasury Obligations, Principal Value | [1] | $ 5,000,000 | | | |
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] | 33.13% | | | |
United States Treasury Obligations, Value | [1],[2] | $ 10,977,799 | | | |
United States Treasury Obligations, Principal Value | [1],[2] | $ 11,000,000 | | | |
Investment Interest Rate | [1],[2] | 2.375% | | | |
Investment Maturity Date | [1],[2] | May 2, 2019 | | | |
Restricted for maintenance margin | | $ 1,606,619 | | | |
U.S. Treasury Bills, 2.470% due July 11, 2019 [Member] | | | | | |
Schedule Of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | 26.99% | | | |
United States Treasury Obligations, Value | [1] | $ 8,940,309 | | | |
United States Treasury Obligations, Principal Value | [1] | $ 9,000,000 | | | |
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 | [1] | 93.30% | | 94.95% | |
United States Treasury Obligations, Value | [1] | $ 30,909,645 | | $ 27,887,293 | |
Investments in Securities, cost | [1] | $ 30,908,318 | | $ 27,886,604 | |
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 | | 6.85% | [3] | 6.11% | [4] |
Affiliated investments, value | | $ 2,271,254 | [3] | $ 1,793,677 | [4] |
Shares | | 2,271,254 | [3] | 1,793,677 | [4] |
Investment Interest Rate | | 2.33% | [3] | 2.30% | [4] |
Investments in Securities, cost | | $ 2,271,254 | [3] | $ 1,793,677 | [4] |
U.S. Treasury Bills, 2.175% due January 3, 2019 [Member] | | | | | |
Schedule Of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | | | 34.05% | |
United States Treasury Obligations, Value | [1] | | | $ 9,999,377 | |
United States Treasury Obligations, Principal Value | [1] | | | $ 10,000,000 | |
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] | | | 16.96% | |
United States Treasury Obligations, Value | [1] | | | $ 4,981,188 | |
United States Treasury Obligations, Principal Value | [1] | | | $ 5,000,000 | |
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],[5] | | | 23.64% | |
United States Treasury Obligations, Value | [1],[5] | | | $ 6,943,854 | |
United States Treasury Obligations, Principal Value | [1],[5] | | | $ 7,000,000 | |
Investment Interest Rate | [1],[5] | | | 2.43% | |
Investment Maturity Date | [1],[5] | | | May 2, 2019 | |
Restricted for maintenance margin | | | | $ 605,120 | |
| |
[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 $1,606,619 are on deposit with the Commodity Broker and held as maintenance margin for open futures contracts. | |
[3] | 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. | |
[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] | United States Treasury Obligations of $605,120 are on deposit with the Commodity Broker and held as maintenance margin for open futures contracts. | |