Schedule of Investments (Unaudited) - Treasury Bills and Affiliated Investments - USD ($) | 12 Months Ended |
Dec. 31, 2017 | Dec. 31, 2016 |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | | 98.81% | | 100.17% | |
Value | | $ 311,472,491 | | $ 438,601,879 | |
Affiliated Investments, at Value | | 17,412,477 | | 14,942,839 | |
Total Investments in Securities | | 328,884,968 | | 453,544,718 | |
Investments, cost | | $ 328,926,740 | | 453,552,275 | |
Affiliated Investments [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | | 5.23% | | | |
Affiliated Investments, at Value | | $ 17,412,477 | | | |
Affiliated Investments, at Cost | | $ 17,417,436 | | $ 14,942,839 | |
U.S. Treasury Bills, 1.180% due January 4, 2018 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | 15.92% | | | |
Value | [1] | $ 52,996,676 | | | |
Principal Value | [1] | $ 53,000,000 | | | |
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] | 2.70% | | | |
Value | [1] | $ 8,995,065 | | | |
Principal Value | [1] | $ 9,000,000 | | | |
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] | 24.89% | | | |
Value | [1] | $ 82,851,845 | | | |
Principal Value | [1] | $ 83,000,000 | | | |
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] | 47.98% | | | |
Value | [1],[2] | $ 159,673,267 | | | |
Principal Value | [1],[2] | $ 160,000,000 | | | |
Investment Interest Rate | [1] | 1.285% | | | |
Investment Maturity Date | [1] | Mar. 1, 2018 | | | |
Restricted for maintenance margin | | $ 39,916,000 | | | |
U.S. Treasury Bills, 1.450% due June 7, 2018 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | 2.09% | | | |
Value | [1] | $ 6,955,638 | | | |
Principal Value | [1] | $ 7,000,000 | | | |
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 | | 93.58% | [1] | 96.87% | [3] |
Value | | $ 311,472,491 | [1] | $ 438,601,879 | [3] |
Investments, cost | | $ 311,509,304 | [1] | $ 438,609,436 | [3],[4] |
Exchange-Traded Fund - PowerShares Treasury Collateral Portfolio [Member] | Affiliated Investments [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [5] | 1.50% | | | |
Affiliated Investments, at Value | [5] | $ 5,000,325 | | | |
Affiliated Investments, Shares | [5] | 47,500 | | | |
Affiliated Investments, at Cost | [5] | $ 5,005,284 | | | |
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 | | 3.73% | [6] | 3.30% | [7] |
Affiliated Investments, at Value | | $ 12,412,152 | [6] | $ 14,942,839 | [7] |
Affiliated Investments, Shares | | 12,412,152 | [6] | 14,942,839 | [7] |
Investment Interest Rate | | 1.15% | [6] | 0.41% | [7] |
Affiliated Investments, at Cost | | $ 12,412,152 | [6] | $ 14,942,839 | [7] |
U.S. Treasury Bills, 0.490% due January 19, 2017 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [3] | | | 9.50% | |
Value | [3] | | | $ 42,992,217 | |
Principal Value | [3] | | | $ 43,000,000 | |
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] | | | 25.17% | |
Value | [3] | | | $ 113,970,018 | |
Principal Value | [3] | | | $ 114,000,000 | |
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] | | | 36.41% | |
Value | [3] | | | $ 164,873,775 | |
Principal Value | [3] | | | $ 165,000,000 | |
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] | | | 7.06% | |
Value | [3] | | | $ 31,956,864 | |
Principal Value | [3] | | | $ 32,000,000 | |
Investment Interest Rate | [3] | | | 0.53% | |
Investment Maturity Date | [3] | | | Apr. 6, 2017 | |
U.S. Treasury Bills, 0.625% due May 18, 2017 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [3],[4] | | | 18.73% | |
Value | [3],[4] | | | $ 84,809,005 | |
Principal Value | [3],[4] | | | $ 85,000,000 | |
Investment Interest Rate | [3] | | | 0.625% | |
Investment Maturity Date | [3] | | | May 18, 2017 | |
Restricted for maintenance margin | | | | $ 54,873,500 | |
| |
[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 $39,916,000 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] | United States Treasury Obligations of $54,873,500 are on deposit with the Commodity Broker and held as maintenance margin for open futures contracts. | |
[5] | Affiliated company. The security and the Fund are affiliated by having the same investment adviser. See Note 8. | |
[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, 2017. | |
[7] | 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. | |