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 | | 99.81% | | 101.51% | |
United States Treasury Obligations, Value | | $ 137,496,222 | | $ 88,687,386 | |
Affiliated Investments, Value | | 5,148,801 | | 7,355,184 | |
Investments in Securities, Value | | 142,645,023 | | 96,042,570 | |
Investments in Securities, Cost | | 142,641,630 | | 96,050,614 | |
Restricted for maintenance margin | | $ 15,098,160 | | $ 11,157,440 | |
U.S. Treasury Bills, 2.465% due April 4, 2019 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | | 4.20% | [1] | 6.30% | [2] |
United States Treasury Obligations, Value | | $ 5,998,822 | [1] | $ 5,962,874 | [2] |
United States Treasury Obligations, Principal Value | | $ 6,000,000 | [1] | $ 6,000,000 | [2] |
Investment Interest Rate | | 2.465% | [1] | 2.465% | [2] |
Investment Maturity Date | | Apr. 4, 2019 | [1] | Apr. 4, 2019 | [2] |
U.S. Treasury Bills, 2.470% due April 23, 2019 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | 39.13% | | | |
United States Treasury Obligations, Value | [1] | $ 55,918,403 | | | |
United States Treasury Obligations, Principal Value | [1] | $ 56,000,000 | | | |
Investment Interest Rate | [1] | 2.47% | | | |
Investment Maturity Date | [1] | Apr. 23, 2019 | | | |
U.S. Treasury Bills, 2.470% due July 11, 2019 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1],[3] | 40.31% | | | |
United States Treasury Obligations, Value | [1],[3] | $ 57,615,325 | | | |
United States Treasury Obligations, Principal Value | [1],[3] | $ 58,000,000 | | | |
Investment Interest Rate | [1],[3] | 2.47% | | | |
Investment Maturity Date | [1],[3] | Jul. 11, 2019 | | | |
U.S. Treasury Bills, 2.375% due May 2, 2019 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | 12.57% | | | |
United States Treasury Obligations, Value | [1] | $ 17,963,672 | | | |
United States Treasury Obligations, Principal Value | [1] | $ 18,000,000 | | | |
Investment Interest Rate | [1] | 2.375% | | | |
Investment Maturity Date | [1] | May 2, 2019 | | | |
United States Treasury Obligations [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | | 96.21% | [1] | 93.74% | [2] |
United States Treasury Obligations, Value | | $ 137,496,222 | [1] | $ 88,687,386 | [2] |
Investments in Securities, Cost | | $ 137,492,829 | [1] | $ 88,695,430 | [2] |
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 | | 3.60% | [4] | 7.77% | [5] |
Affiliated Investments, Value | | $ 5,148,801 | [4] | $ 7,355,184 | [5] |
Affiliated Investments, Shares | | 5,148,801 | [4] | 7,355,184 | [5] |
Investment Interest Rate | | 2.33% | [1],[4] | 2.30% | [2],[5] |
Investments in Securities, Cost | | $ 5,148,801 | [4] | $ 7,355,184 | [5] |
U.S. Treasury Bills, 2.175% due January 3, 2019 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [2] | | | 19.03% | |
United States Treasury Obligations, Value | [2] | | | $ 17,998,877 | |
United States Treasury Obligations, Principal Value | [2] | | | $ 18,000,000 | |
Investment Interest Rate | [2] | | | 2.175% | |
Investment Maturity Date | [2] | | | Jan. 3, 2019 | |
U.S. Treasury Bills, 2.430% due May 2, 2019 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [2] | | | 7.34% | |
United States Treasury Obligations, Value | [2] | | | $ 6,943,854 | |
United States Treasury Obligations, Principal Value | [2] | | | $ 7,000,000 | |
Investment Interest Rate | [2] | | | 2.43% | |
Investment Maturity Date | [2] | | | May 2, 2019 | |
U.S. Treasury Bills, 2.370% due February 28, 2019 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [2],[6] | | | 61.07% | |
United States Treasury Obligations, Value | [2],[6] | | | $ 57,781,781 | |
United States Treasury Obligations, Principal Value | [2],[6] | | | $ 58,000,000 | |
Investment Interest Rate | [2],[6] | | | 2.37% | |
Investment Maturity Date | [2],[6] | | | Feb. 28, 2019 | |
| |
[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] | 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 | |
[3] | United States Treasury Obligations of $15,098,160 are on deposit with the Commodity Broker and held as maintenance margin for open futures contracts. | |
[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 $11,157,440 are on deposit with the Commodity Broker and held as maintenance margin for open futures contracts. | |