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 | | 99.73% | | 99.97% | |
United States Treasury Obligations, Value | | $ 12,939,628 | | $ 9,995,676 | |
Affiliated Investments, Value | | 473,046 | | 3,829,452 | |
Investments in Securities, Value | | 13,412,674 | | 13,825,128 | |
Investments in Securities, Cost | | $ 13,410,980 | | $ 13,824,819 | |
U.S. Treasury Bills, 2.375% due July 11, 2019 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1],[2] | 89.18% | | | |
United States Treasury Obligations, Value | [1],[2] | $ 11,993,592 | | | |
United States Treasury Obligations, Principal Value | [1],[2] | $ 12,000,000 | | | |
Investment Interest Rate | [1],[2] | 2.375% | | | |
Investment Maturity Date | [1],[2] | Jul. 11, 2019 | | | |
Restricted for maintenance margin | [1],[2] | $ 1,998,800 | | | |
U.S. Treasury Bills, 2.240% due September 12 , 2019 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | | 7.03% | | | |
United States Treasury Obligations, Value | | $ 946,036 | | | |
United States Treasury Obligations, Principal Value | | $ 950,000 | | | |
Investment Interest Rate | | 2.24% | | | |
Investment Maturity Date | | Sep. 12, 2019 | | | |
United States Treasury Obligations [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | 96.21% | | 72.28% | |
United States Treasury Obligations, Value | [1] | $ 12,939,628 | | $ 9,995,676 | |
Investments in Securities, Cost | [1] | $ 12,937,934 | | $ 9,995,367 | |
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 | | 3.52% | [3] | 27.69% | [4] |
Affiliated Investments, Value | | $ 473,046 | [3] | $ 3,829,452 | [4] |
Affiliated Investments, Shares | | 473,046 | [3] | 3,829,452 | [4] |
Investment Interest Rate | | 2.26% | [3] | 2.30% | [4] |
Investments in Securities, Cost | | $ 473,046 | [3] | $ 3,829,452 | [4] |
U.S. Treasury Bills, 2.175% due January 3, 2019 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1],[5] | | | 65.08% | |
United States Treasury Obligations, Value | [1],[5] | | | $ 8,999,439 | |
United States Treasury Obligations, Principal Value | [1],[5] | | | $ 9,000,000 | |
Investment Interest Rate | [1],[5] | | | 2.175% | |
Investment Maturity Date | [1],[5] | | | Jan. 3, 2019 | |
Restricted for maintenance margin | [1],[5] | | | $ 2,599,740 | |
U.S. Treasury Bills, 2.370% due February 28, 2019 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | | | 7.20% | |
United States Treasury Obligations, Value | [1] | | | $ 996,237 | |
United States Treasury Obligations, Principal Value | [1] | | | $ 1,000,000 | |
Investment Interest Rate | [1] | | | 2.37% | |
Investment Maturity Date | [1] | | | Feb. 28, 2019 | |
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[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 $1,998,800 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 June 30, 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 $2,599,740 are on deposit with the Commodity Broker and held as maintenance margin for open futures contracts. | |