Statement of Changes in Shareholders' Equity (Unaudited) - USD ($) | Total | General Shares [Member] | Shares [Member] |
Balance - Value at Dec. 31, 2016 | $ 193,214,737 | $ 552 | $ 193,214,185 |
Balance - Shares at Dec. 31, 2016 | | 40 | 14,000,000 |
Purchases of Shares - Value | 94,277,443 | | $ 94,277,443 |
Purchases of Shares - Shares | | | 7,400,000 |
Redemption of Shares - Value | (124,986,469) | | $ (124,986,469) |
Redemption of Shares - Shares | | | (10,000,000) |
Net Increase (Decrease) due to Share Transactions, value | (30,709,026) | | $ (30,709,026) |
Net Increase (Decrease) due to Share Transactions, shares | | | (2,600,000) |
Net Income (Loss) | | | |
Net Investment Income (Loss) | (149,707) | | $ (149,707) |
Net Realized Gain (Loss) on United States Treasury Obligations, Affiliated Investments and Commodity Futures Contracts | (7,494,936) | $ (18) | (7,494,918) |
Net Change in Unrealized Gain (Loss) on United States Treasury Obligations, Affiliated Investments and Commodity Futures Contracts | (8,021,709) | (19) | (8,021,690) |
Net Income (Loss) | (15,666,352) | (37) | (15,666,315) |
Net Change in Shareholders' Equity, value | (46,375,378) | (37) | $ (46,375,341) |
Net Change in Shareholders' Equity, shares | | | (2,600,000) |
Balance - Value at Sep. 30, 2017 | 146,839,359 | $ 515 | $ 146,838,844 |
Balance - Shares at Sep. 30, 2017 | | 40 | 11,400,000 |
Balance - Value at Jun. 30, 2017 | 99,704,049 | $ 464 | $ 99,703,585 |
Balance - Shares at Jun. 30, 2017 | | 40 | 8,600,000 |
Purchases of Shares - Value | 51,820,918 | | $ 51,820,918 |
Purchases of Shares - Shares | | | 4,200,000 |
Redemption of Shares - Value | (17,076,735) | | $ (17,076,735) |
Redemption of Shares - Shares | | | (1,400,000) |
Net Increase (Decrease) due to Share Transactions, value | 34,744,183 | | $ 34,744,183 |
Net Increase (Decrease) due to Share Transactions, shares | | | 2,800,000 |
Net Income (Loss) | | | |
Net Investment Income (Loss) | 30,952 | $ 1 | $ 30,951 |
Net Realized Gain (Loss) on United States Treasury Obligations, Affiliated Investments and Commodity Futures Contracts | (2,183,069) | (2) | (2,183,067) |
Net Change in Unrealized Gain (Loss) on United States Treasury Obligations, Affiliated Investments and Commodity Futures Contracts | 14,543,244 | 52 | 14,543,192 |
Net Income (Loss) | 12,391,127 | 51 | 12,391,076 |
Net Change in Shareholders' Equity, value | 47,135,310 | 51 | $ 47,135,259 |
Net Change in Shareholders' Equity, shares | | | 2,800,000 |
Balance - Value at Sep. 30, 2017 | 146,839,359 | $ 515 | $ 146,838,844 |
Balance - Shares at Sep. 30, 2017 | | 40 | 11,400,000 |
Balance - Value at Dec. 31, 2017 | 178,048,939 | $ 584 | $ 178,048,355 |
Balance - Shares at Dec. 31, 2017 | | 40 | 12,200,000 |
Purchases of Shares - Value | 61,599,049 | | $ 61,599,049 |
Purchases of Shares - Shares | | | 3,800,000 |
Redemption of Shares - Value | (54,514,021) | | $ (54,514,021) |
Redemption of Shares - Shares | | | (3,400,000) |
Net Increase (Decrease) due to Share Transactions, value | 7,085,028 | | $ 7,085,028 |
Net Increase (Decrease) due to Share Transactions, shares | | | 400,000 |
Net Income (Loss) | | | |
Net Investment Income (Loss) | 1,487,889 | $ 5 | $ 1,487,884 |
Net Realized Gain (Loss) on United States Treasury Obligations, Affiliated Investments and Commodity Futures Contracts | 21,621,077 | 70 | 21,621,007 |
Net Change in Unrealized Gain (Loss) on United States Treasury Obligations, Affiliated Investments and Commodity Futures Contracts | 19,850,525 | 65 | 19,850,460 |
Net Income (Loss) | 42,959,491 | 140 | 42,959,351 |
Net Change in Shareholders' Equity, value | 50,044,519 | 140 | $ 50,044,379 |
Net Change in Shareholders' Equity, shares | | | 400,000 |
Balance - Value at Sep. 30, 2018 | 228,093,458 | $ 724 | $ 228,092,734 |
Balance - Shares at Sep. 30, 2018 | | 40 | 12,600,000 |
Balance - Value at Jun. 30, 2018 | 225,702,001 | $ 684 | $ 225,701,317 |
Balance - Shares at Jun. 30, 2018 | | 40 | 13,200,000 |
Purchases of Shares - Value | 23,484,533 | | $ 23,484,533 |
Purchases of Shares - Shares | | | 1,400,000 |
Redemption of Shares - Value | (33,277,982) | | $ (33,277,982) |
Redemption of Shares - Shares | | | (2,000,000) |
Net Increase (Decrease) due to Share Transactions, value | (9,793,449) | | $ (9,793,449) |
Net Increase (Decrease) due to Share Transactions, shares | | | (600,000) |
Net Income (Loss) | | | |
Net Investment Income (Loss) | 850,209 | $ 3 | $ 850,206 |
Net Realized Gain (Loss) on United States Treasury Obligations, Affiliated Investments and Commodity Futures Contracts | 3,514,109 | 11 | 3,514,098 |
Net Change in Unrealized Gain (Loss) on United States Treasury Obligations, Affiliated Investments and Commodity Futures Contracts | 7,820,588 | 26 | 7,820,562 |
Net Income (Loss) | 12,184,906 | 40 | 12,184,866 |
Net Change in Shareholders' Equity, value | 2,391,457 | 40 | $ 2,391,417 |
Net Change in Shareholders' Equity, shares | | | (600,000) |
Balance - Value at Sep. 30, 2018 | $ 228,093,458 | $ 724 | $ 228,092,734 |
Balance - Shares at Sep. 30, 2018 | | 40 | 12,600,000 |