Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash Flows from Operating Activities
Net increase (decrease) in net assets resulting from operations	$ (368,101,390)	$ 170,312,850
Adjustments to reconcile net increase (decrease) in net assets resulting from operations to net cash provided by (used in) operating activities:
Purchases of short-term investments	(1,053,640,337)	(2,810,580,854)
Sales/maturities of short-term investments	1,316,070,743	2,769,870,170
Accretion of discount	(2,571,347)	(7,204,768)
Net realized (gain) loss on short-term investments	(31,929)	(101)
Net change in unrealized appreciation/depreciation on short-term investments	(630,155)	(138,118)
Change in operating assets and liabilities:
Receivable for variation margin on open futures contracts	(5,954,273)	(3,417,114)
Payable for variation margin on open futures contracts	(5,952,581)	0
Sponsor’s fees payable	(74,571)	6,030
Brokerage commissions and fees payable	0	(8,046)
Net cash provided by (used in) operating activities	(120,885,840)	118,840,049
Cash Flows from Financing Activities
Contributions for Shares issued	134,854,545	24,217,916
Distributions for Shares redeemed	(40,549,504)	(138,042,487)
Net cash provided by (used in) financing activities	94,305,041	(113,824,571)
Net increase (decrease) in cash	(26,580,799)	5,015,478
Cash
Beginning of year, Unrestricted — cash	31,242,158	10,033,297
End of year, Unrestricted — cash	$ 4,661,359	$ 15,048,775