Schedule of Investments - Treasury Bills and Affiliated Investments - USD ($) | 12 Months Ended |
Dec. 31, 2017 | Dec. 31, 2016 |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | | 98.90% | | 100.01% | |
Value | | $ 142,797,721 | | $ 183,837,528 | |
Affiliated investments, at value | | 33,284,413 | | 9,388,271 | |
Total Investments in Securities | | 176,082,134 | | 193,225,799 | |
Investments, cost | | $ 176,104,892 | | 193,231,443 | |
Affiliated Investments [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | | 18.70% | | | |
Affiliated investments, at value | | $ 33,284,413 | | | |
Affiliated investments, at cost | | $ 33,304,228 | | $ 9,388,271 | |
U.S. Treasury Bills, 1.180% due January 4, 2018 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | 27.52% | | | |
Value | [1] | $ 48,996,927 | | | |
Principal Value | [1] | $ 49,000,000 | | | |
Investment Interest Rate | [1] | 1.18% | | | |
Investment Maturity Date | [1] | Jan. 4, 2018 | | | |
U.S. Treasury Bills, 1.245% due January 18, 2018 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | 10.10% | | | |
Value | [1] | $ 17,990,130 | | | |
Principal Value | [1] | $ 18,000,000 | | | |
Investment Interest Rate | [1] | 1.245% | | | |
Investment Maturity Date | [1] | Jan. 18, 2018 | | | |
U.S. Treasury Bills, 1.285% due February 22, 2018 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | 28.59% | | | |
Value | [1] | $ 50,908,965 | | | |
Principal Value | [1] | $ 51,000,000 | | | |
Investment Interest Rate | [1] | 1.285% | | | |
Investment Maturity Date | [1] | Feb. 22, 2018 | | | |
U.S. Treasury Bills, 1.285% due March 1, 2018 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1],[2] | 7.85% | | | |
Value | [1],[2] | $ 13,971,411 | | | |
Principal Value | [1],[2] | $ 14,000,000 | | | |
Investment Interest Rate | [1] | 1.285% | | | |
Investment Maturity Date | [1] | Mar. 1, 2018 | | | |
Restricted for maintenance margin | | $ 13,970,600 | | | |
U.S. Treasury Bills, 1.450% due June 7, 2018 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | 6.14% | | | |
Value | [1] | $ 10,930,288 | | | |
Principal Value | [1] | $ 11,000,000 | | | |
Investment Interest Rate | [1] | 1.45% | | | |
Investment Maturity Date | [1] | Jun. 7, 2018 | | | |
United States Treasury Obligations [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | | 80.20% | [1] | 95.15% | [3] |
Value | | $ 142,797,721 | [1] | $ 183,837,528 | [3] |
Investments, cost | | $ 142,800,664 | | $ 183,843,172 | |
Exchange-Traded Fund - PowerShares Treasury Collateral Portfolio [Member] | Affiliated Investments [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [4] | 11.22% | | | |
Affiliated investments, at value | [4] | $ 19,980,246 | | | |
Shares | [4] | 189,800 | | | |
Affiliated investments, at cost | [4] | $ 20,000,061 | | | |
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 | | 7.48% | [5] | 4.86% | [6] |
Affiliated investments, at value | | $ 13,304,167 | [5] | $ 9,388,271 | [6] |
Shares | | 13,304,167 | [5] | 9,388,271 | [6] |
Investment Interest Rate | | 1.15% | [5] | 0.41% | [6] |
Affiliated investments, at cost | | $ 13,304,167 | [5] | $ 9,388,271 | [6] |
U.S. Treasury Bills, 0.490% due January 19, 2017 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [3] | | | 9.83% | |
Value | [3] | | | $ 18,996,561 | |
Principal Value | [3] | | | $ 19,000,000 | |
Investment Interest Rate | [3] | | | 0.49% | |
Investment Maturity Date | [3] | | | Jan. 19, 2017 | |
U.S. Treasury Bills, 0.485% due January 26, 2017 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [3] | | | 25.35% | |
Value | [3] | | | $ 48,987,113 | |
Principal Value | [3] | | | $ 49,000,000 | |
Investment Interest Rate | [3] | | | 0.485% | |
Investment Maturity Date | [3] | | | Jan. 26, 2017 | |
U.S. Treasury Bills, 0.490% due March 2, 2017 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [3] | | | 27.41% | |
Value | [3] | | | $ 52,959,455 | |
Principal Value | [3] | | | $ 53,000,000 | |
Investment Interest Rate | [3] | | | 0.49% | |
Investment Maturity Date | [3] | | | Mar. 2, 2017 | |
U.S. Treasury Bills, 0.530% due April 6, 2017 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [3],[7] | | | 20.68% | |
Value | [3],[7] | | | $ 39,946,080 | |
Principal Value | [3],[7] | | | $ 40,000,000 | |
Investment Interest Rate | [3],[7] | | | 0.53% | |
Investment Maturity Date | [3],[7] | | | Apr. 6, 2017 | |
Restricted for maintenance margin | | | | $ 22,967,800 | |
U.S. Treasury Bills, 0.625% due May 18, 2017 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [3] | | | 11.88% | |
Value | [3] | | | $ 22,948,319 | |
Principal Value | [3] | | | $ 23,000,000 | |
Investment Interest Rate | [3] | | | 0.625% | |
Investment Maturity Date | [3] | | | May 18, 2017 | |
| |
[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 $13,970,600 are on deposit with the Commodity Broker and held as maintenance margin for open futures contracts. | |
[3] | 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 year end. | |
[4] | Affiliated company. The security and the Fund are affiliated by having the same investment adviser. See Note 8. | |
[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, 2017. | |
[6] | 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, 2016. | |
[7] | United States Treasury Obligations of $22,967,800 are on deposit with the Commodity Broker and held as maintenance margin for open futures contracts. | |