Statements of Operations - USD ($)		12 Months Ended
		Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Investment Income
Interest		$ 21,394,995	$ 24,497,221	$ 9,707,419
Total investment income		21,394,995	24,497,221	9,707,419
Expenses
Sponsor’s fees		7,353,186	10,502,114	8,530,039
Brokerage commissions and fees		1,015,967	1,422,790	1,337,872
Total expenses		8,369,153	11,924,904	9,867,911
Net investment income (loss)		13,025,842	12,572,317	(160,492)
Net Realized and Unrealized Gain (Loss)
Short-term investments		96,367	3,343	2,812
Futures contracts		25,617,934	(11,940,106)	3,410,884
Net realized gain (loss)		25,714,301	(11,936,763)	3,413,696
Net change in unrealized appreciation/depreciation on:
Short-term investments		38,916	77,730	(59,334)
Futures contracts		136,157,900	(190,921,734)	77,224,746
Net change in unrealized appreciation/depreciation		136,196,816	(190,844,004)	77,165,412
Net realized and unrealized gain (loss)		161,911,117	(202,780,767)	80,579,108
Net increase (decrease) in net assets resulting from operations		$ 174,936,959	$ (190,208,450)	$ 80,418,616
Net increase (decrease) in net assets per Share (in dollars per share)	[1]	$ 2.79	$ (2.29)	$ 1.05

[1] Net increase (decrease) in net assets per Share based on average shares outstanding during the year.