Statements of Changes in Shareholders' Equity and Redeemable Capital Shares (unaudited) - USD ($) | Total | Retained Earnings [Member] | Redeemable Capital Shares [Member] |
Balance at Dec. 31, 2018 | | | $ 316,828,837 |
Balance, Shares at Dec. 31, 2018 | | | 2,900,000 |
Purchases of Shares | | | $ 197,447,849 |
Purchases of Shares, Shares | | | 1,850,000 |
Redemption of Shares | | | $ (248,252,458) |
Redemption of Shares, Shares | | | (2,300,000) |
Net Increase (Decrease) due to Share Transactions | | | $ (50,804,609) |
Net Increase (Decrease) due to Share Transactions, Shares | | | (450,000) |
Net Comprehensive Income (Loss) | $ (1,435,121) | $ (1,435,121) | |
Adjustment of Redeemable Capital Shares to Redemption Value related to Retained Earnings | 1,435,121 | 1,435,121 | $ (1,435,121) |
Adjustment of Redeemable Capital Shares to Redemption Value | | | (10,864,366) |
Balance at Sep. 30, 2019 | | | $ 253,724,741 |
Balance, Shares at Sep. 30, 2019 | | | 2,450,000 |
Balance at Jun. 30, 2019 | | | $ 222,216,366 |
Balance, Shares at Jun. 30, 2019 | | | 2,050,000 |
Purchases of Shares | | | $ 84,609,381 |
Purchases of Shares, Shares | | | 800,000 |
Redemption of Shares | | | $ (42,457,504) |
Redemption of Shares, Shares | | | (400,000) |
Net Increase (Decrease) due to Share Transactions | | | $ 42,151,877 |
Net Increase (Decrease) due to Share Transactions, Shares | | | 400,000 |
Net Comprehensive Income (Loss) | (475,453) | (475,453) | |
Adjustment of Redeemable Capital Shares to Redemption Value related to Retained Earnings | 475,453 | 475,453 | $ (475,453) |
Adjustment of Redeemable Capital Shares to Redemption Value | | | (10,168,049) |
Balance at Sep. 30, 2019 | | | $ 253,724,741 |
Balance, Shares at Sep. 30, 2019 | | | 2,450,000 |
Balance at Dec. 31, 2019 | $ 287,263,846 | | $ 287,263,846 |
Balance, Shares at Dec. 31, 2019 | 2,700,000 | | 2,700,000 |
Purchases of Shares | | | $ 318,210,622 |
Purchases of Shares, Shares | | | 2,950,000 |
Redemption of Shares | | | $ (270,204,291) |
Redemption of Shares, Shares | | | (2,550,000) |
Net Increase (Decrease) due to Share Transactions | | | $ 48,006,331 |
Net Increase (Decrease) due to Share Transactions, Shares | | | 400,000 |
Net Comprehensive Income (Loss) | $ (1,865,025) | (1,865,025) | |
Adjustment of Redeemable Capital Shares to Redemption Value related to Retained Earnings | 1,865,025 | 1,865,025 | $ (1,865,025) |
Adjustment of Redeemable Capital Shares to Redemption Value | | | 8,811,457 |
Balance at Sep. 30, 2020 | $ 342,216,609 | | $ 342,216,609 |
Balance, Shares at Sep. 30, 2020 | 3,100,000 | | 3,100,000 |
Balance at Jun. 30, 2020 | | | $ 206,646,067 |
Balance, Shares at Jun. 30, 2020 | | | 1,950,000 |
Purchases of Shares | | | $ 199,309,922 |
Purchases of Shares, Shares | | | 1,800,000 |
Redemption of Shares | | | $ (72,101,928) |
Redemption of Shares, Shares | | | (650,000) |
Net Increase (Decrease) due to Share Transactions | | | $ 127,207,994 |
Net Increase (Decrease) due to Share Transactions, Shares | | | 1,150,000 |
Net Comprehensive Income (Loss) | $ (722,810) | (722,810) | |
Adjustment of Redeemable Capital Shares to Redemption Value related to Retained Earnings | 722,810 | $ 722,810 | $ (722,810) |
Adjustment of Redeemable Capital Shares to Redemption Value | | | 9,085,358 |
Balance at Sep. 30, 2020 | $ 342,216,609 | | $ 342,216,609 |
Balance, Shares at Sep. 30, 2020 | 3,100,000 | | 3,100,000 |