Schedule of Investments (Unaudited) - Treasury Bills and Affiliated Investments - USD ($) | 9 Months Ended | 12 Months Ended |
Sep. 30, 2017 | Dec. 31, 2016 |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | | 99.54% | | 99.78% | |
Value | | $ 595,411,380 | | $ 702,215,941 | |
Affiliated Investments, at Value | | 113,506,259 | | 19,456,137 | |
Total Investments in Securities | | 708,917,639 | | 721,672,078 | |
Investments, cost | | $ 708,515,913 | | 721,689,108 | |
Affiliated Investments [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | | 15.94% | | | |
Affiliated Investments, at Value | | $ 113,506,259 | | | |
Affiliated Investments, at Cost | | $ 113,149,702 | | $ 19,456,137 | |
U.S. Treasury Bills, 0.970% due October 26, 2017 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | 2.53% | | | |
Value | [1] | $ 17,988,825 | | | |
Principal Value | [1] | $ 18,000,000 | | | |
Investment Interest Rate | [1] | 0.97% | | | |
Investment Maturity Date | [1] | Oct. 26, 2017 | | | |
U.S. Treasury Bills, 1.000% due November 24, 2017 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | 14.16% | | | |
Value | [1] | $ 100,852,914 | | | |
Principal Value | [1] | $ 101,000,000 | | | |
Investment Interest Rate | [1] | 1.00% | | | |
Investment Maturity Date | [1] | Nov. 24, 2017 | | | |
U.S. Treasury Bills, 1.020% due December 7, 2017 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | 23.13% | | | |
Value | [1] | $ 164,703,549 | | | |
Principal Value | [1] | $ 165,000,000 | | | |
Investment Interest Rate | [1] | 1.02% | | | |
Investment Maturity Date | [1] | Dec. 7, 2017 | | | |
U.S. Treasury Bills, 1.050% due January 4, 2018 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1],[2] | 22.96% | | | |
Value | [1],[2] | $ 163,559,873 | | | |
Principal Value | [1],[2] | $ 164,000,000 | | | |
Investment Interest Rate | [1],[2] | 1.05% | | | |
Investment Maturity Date | [1],[2] | Jan. 4, 2018 | | | |
Restricted for maintenance margin | | $ 104,716,500 | | | |
U.S. Treasury Bills, 1.115% due March 1, 2018 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [1] | 20.82% | | | |
Value | [1] | $ 148,306,219 | | | |
Principal Value | [1] | $ 149,000,000 | | | |
Investment Interest Rate | [1] | 1.115% | | | |
Investment Maturity Date | | Mar. 1, 2018 | | | |
United States Treasury Obligations [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | | 83.60% | [1] | 97.09% | [3] |
Value | | $ 595,411,380 | [1] | $ 702,215,941 | [3] |
Investments, cost | | $ 595,366,211 | | $ 702,232,971 | |
Exchange-Traded Fund - PowerShares Treasury Collateral Portfolio [Member] | Affiliated Investments [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [4],[5] | 11.14% | | | |
Affiliated Investments, at Value | [4],[5] | $ 79,355,745 | | | |
Shares | [4],[5] | 749,700 | | | |
Affiliated Investments, at Cost | [4],[5] | $ 78,999,188 | | | |
Money Market Mutual Fund - Premier U.S. Government Money Portfolio - Institutional Class [Member] | Affiliated Investments [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | | 4.80% | [6] | 2.69% | [3] |
Affiliated Investments, at Value | | $ 34,150,514 | [6] | $ 19,456,137 | [3] |
Shares | | 34,150,514 | [6] | 19,456,137 | [3] |
Investment Interest Rate | | 0.92% | [6] | 0.41% | [3],[7] |
Affiliated Investments, at Cost | | $ 34,150,514 | [6] | $ 19,456,137 | [7] |
U.S. Treasury Bills, 0.490% due January 19, 2017 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [3] | | | 17.56% | |
Value | [3] | | | $ 126,977,013 | |
Principal Value | [3] | | | $ 127,000,000 | |
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] | | | 9.81% | |
Value | [3] | | | $ 70,981,327 | |
Principal Value | [3] | | | $ 71,000,000 | |
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] | | | 17.13% | |
Value | [3] | | | $ 123,905,140 | |
Principal Value | [3] | | | $ 124,000,000 | |
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],[8] | | | 32.03% | |
Value | [3],[8] | | | $ 231,687,264 | |
Principal Value | [3],[8] | | | $ 232,000,000 | |
Investment Interest Rate | [3],[8] | | | 0.53% | |
Investment Maturity Date | [3],[8] | | | Apr. 6, 2017 | |
Restricted for maintenance margin | | | | $ 104,853,000 | |
U.S. Treasury Bills, 0.625% due May 18, 2017 [Member] | | | | | |
Schedule of Investments [Line Items] | | | | | |
Percentage of Shareholders' Equity | [3] | | | 20.56% | |
Value | [3] | | | $ 148,665,197 | |
Principal Value | [3] | | | $ 149,000,000 | |
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 $104,716,500 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] | Non-income producing security. | |
[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 September 30, 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. | |
[8] | United States Treasury Obligations of $104,853,000 are on deposit with the Commodity Broker and held as maintenance margin for open futures contracts. | |