Schedule of Investments - Treasury Bills and Money Market Fund - USD ($) | 12 Months Ended |
Dec. 31, 2018 | Dec. 31, 2017 |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | | 100.99% | | 98.62% | |
United States Treasury Obligations, Value | | $ 101,406,388 | | $ 138,760,422 | |
Affiliated investments, at value and cost | | 8,547,404 | | 13,842,579 | |
Investments in Securities, Value | | 109,953,792 | | 152,603,001 | |
Investments in Securities, Cost | | $ 109,942,077 | | $ 152,607,828 | |
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, 2.430% due May 2, 2019 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1],[2] | 64.69% | | | |
United States Treasury Obligations, Value | [1],[2] | $ 70,430,521 | | | |
United States Treasury Obligations, Principal Value | [1],[2] | $ 71,000,000 | | | |
Investment Interest Rate | [1],[2] | 2.43% | | | |
Investment Maturity Date | [1],[2] | May 2, 2019 | | | |
Restricted for maintenance margin | | $ 12,003,200 | | | |
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] | 2.37% | | | |
Investment Maturity Date | [1],[2] | Feb. 28, 2019 | | | |
United States Treasury Obligations [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | 93.14% | | 89.68% | |
United States Treasury Obligations, Value | [1] | $ 101,406,388 | | $ 138,760,422 | |
Investments in Securities, Cost | | $ 101,394,673 | | $ 138,765,249 | [1] |
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] | 7.85% | | 8.94% | |
Affiliated investments, at value and cost | [3] | $ 8,547,404 | | $ 13,842,579 | |
Affiliated Investments, Shares | [3] | 8,547,404 | | 13,842,579 | |
Investment Interest Rate | | 2.30% | [3] | 1.15% | [4] |
Investments in Securities, Cost | | $ 8,547,404 | [3] | $ 13,842,579 | [4] |
U.S. Treasury Bills, 1.180% due January 4, 2018 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | | | 54.29% | |
United States Treasury Obligations, Value | [1] | | | $ 83,994,732 | |
United States Treasury Obligations, Principal Value | [1] | | | $ 84,000,000 | |
Investment Interest Rate | [1] | | | 1.18% | |
Investment Maturity Date | [1] | | | Jan. 4, 2018 | |
U.S. Treasury Bills, 1.285% due February 22, 2018 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1],[5] | | | 6.45% | |
United States Treasury Obligations, Value | [1],[5] | | | $ 9,982,150 | |
United States Treasury Obligations, Principal Value | [1],[5] | | | $ 10,000,000 | |
Investment Interest Rate | [1],[5] | | | 1.285% | |
Investment Maturity Date | [1],[5] | | | Feb. 22, 2018 | |
Restricted for maintenance margin | | | | $ 25,948,400 | |
U.S. Treasury Bills, 1.285% due March 1, 2018 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1],[5] | | | 10.32% | |
United States Treasury Obligations, Value | [1],[5] | | | $ 15,967,327 | |
United States Treasury Obligations, Principal Value | [1],[5] | | | $ 16,000,000 | |
Investment Interest Rate | [1] | | | 1.285% | |
Investment Maturity Date | [1] | | | Mar. 1, 2018 | |
Restricted for maintenance margin | | | | $ 25,948,400 | |
U.S. Treasury Bills, 1.450% due June 7, 2018 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | | | 18.62% | |
United States Treasury Obligations, Value | [1] | | | $ 28,816,213 | |
United States Treasury Obligations, Principal Value | [1] | | | $ 29,000,000 | |
Investment Interest Rate | [1] | | | 1.45% | |
Investment Maturity Date | [1] | | | Jun. 7, 2018 | |
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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 $12,003,200 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 December 31, 2018. | |
[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, 2017. | |
[5] | United States Treasury Obligations of $25,948,400 are on deposit with the Commodity Broker and held as maintenance margin for open futures contracts. | |