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 | | 99.68% | | 100.99% | |
United States Treasury Obligations, Value | | $ 111,794,178 | | $ 101,406,388 | |
Affiliated investments, at value and cost | | 3,934,393 | | 8,547,404 | |
Investments in Securities, Value | | 115,728,571 | | 109,953,792 | |
Investments in Securities, Cost | | $ 115,721,935 | | $ 109,942,077 | |
U.S. Treasury Bills, 2.465% due April 4, 2019 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | 12.92% | | | |
United States Treasury Obligations, Value | [1] | $ 14,997,055 | | | |
United States Treasury Obligations, Principal Value | [1] | $ 15,000,000 | | | |
Investment Interest Rate | [1] | 2.465% | | | |
Investment Maturity Date | [1] | Apr. 4, 2019 | | | |
U.S. Treasury Bills, 2.470% due April 23, 2019 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | 10.32% | | | |
United States Treasury Obligations, Value | [1] | $ 11,982,515 | | | |
United States Treasury Obligations, Principal Value | [1] | $ 12,000,000 | | | |
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] | 70.49% | | | |
United States Treasury Obligations, Value | [1],[2] | $ 81,834,505 | | | |
United States Treasury Obligations, Principal Value | [1],[2] | $ 82,000,000 | | | |
Investment Interest Rate | [1],[2] | 2.375% | | | |
Investment Maturity Date | [1],[2] | May 2, 2019 | | | |
Restricted for maintenance margin | | $ 14,070,390 | | | |
U.S. Treasury Bills, 2.470% due July 11, 2019 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | 2.56% | | | |
United States Treasury Obligations, Value | [1] | $ 2,980,103 | | | |
United States Treasury Obligations, Principal Value | [1] | $ 3,000,000 | | | |
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] | 96.29% | | 93.14% | |
United States Treasury Obligations, Value | [1] | $ 111,794,178 | | $ 101,406,388 | |
Investments in Securities, Cost | | $ 111,787,542 | | $ 101,394,673 | |
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 | | 3.39% | [3] | 7.85% | [4] |
Affiliated investments, at value and cost | | $ 3,934,393 | [3] | $ 8,547,404 | [4] |
Affiliated Investments, Shares | | 3,934,393 | [3] | 8,547,404 | [4] |
Investment Interest Rate | | 2.33% | [3] | 2.30% | [4] |
Investments in Securities, Cost | | $ 3,934,393 | [3] | $ 8,547,404 | [4] |
U.S. Treasury Bills, 2.175% due January 3, 2019 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | | | 22.96% | |
United States Treasury Obligations, Value | [1] | | | $ 24,998,441 | |
United States Treasury Obligations, Principal Value | [1] | | | $ 25,000,000 | |
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] | | | 5.49% | |
United States Treasury Obligations, Value | [1] | | | $ 5,977,426 | |
United States Treasury Obligations, Principal Value | [1] | | | $ 6,000,000 | |
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] | | | 64.69% | |
United States Treasury Obligations, Value | [1],[5] | | | $ 70,430,521 | |
United States Treasury Obligations, Principal Value | [1],[5] | | | $ 71,000,000 | |
Investment Interest Rate | [1],[5] | | | 2.43% | |
Investment Maturity Date | [1],[5] | | | May 2, 2019 | |
Restricted for maintenance margin | | | | $ 12,003,200 | |
| |
[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 $14,070,390 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 $12,003,200 are on deposit with the Commodity Broker and held as maintenance margin for open futures contracts. | |