Statements of Financial Condition (Parenthetical) - USD ($)	Dec. 31, 2019	Dec. 31, 2018
Investments in Securities, cost	$ 1,432,111,774	$ 2,009,415,674
US Treasury Bill Securities [Member]
Investments in Securities, cost	664,622,057	1,614,486,381
Affiliated Investments [Member]
Affiliated Investments, at Cost	$ 767,489,717	$ 394,929,293