Statements of Financial Condition (Unaudited) (Parenthetical) - USD ($)	Mar. 31, 2020	Dec. 31, 2019
Investments in Securities, cost	$ 288,842,789	$ 347,580,306
US Treasury Bill Securities [Member]
Investments in Securities, cost	144,679,228	147,682,624
Affiliated Investments [Member]
Affiliated Investments, at Cost	$ 144,163,561	$ 199,897,682