Statements of Financial Condition (Unaudited) (Parenthetical) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Investments in Securities, cost	$ 1,018,159,495	$ 1,432,111,774
US Treasury Bill Securities [Member]
Investments in Securities, cost	369,952,285	664,622,057
Affiliated Investments [Member]
Affiliated Investments, at Cost	$ 648,207,210	$ 767,489,717