Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net Income (Loss)	$ 3,885,993	$ 526,591	$ 5,972,133
Adjustments to reconcile net income (loss) to net cash provided by (used for) operating activities:
Cost of securities purchased		(25,949,993)	(39,471,398)
Proceeds from securities sold and matured		34,884,399	35,299,922
Cost of affiliated investments purchased		(27,809,717)
Proceeds from affiliated investments sold		26,218,691
Net accretion of discount on United States Treasury Obligations		(75,997)	(23,297)
Net realized (gain) loss on United States Treasury Obligations and Affiliated Investments	(38)	1,198	(38)
Net change in unrealized (gain) loss on United States Treasury Obligations, Affiliated Investments and Commodity Futures Contracts		481	(732)
Change in operating receivables and liabilities:
Dividends from affiliates		(740)
Variation margin		(324,165)	(320,571)
Management fee		(6,935)	1,943
Brokerage commissions and fees		174	(1,429)
Net cash provided by (used for) operating activities		7,463,987	1,456,533
Cash flows from financing activities:
Proceeds from purchases of Shares		5,755,806
Redemption of Shares		(10,696,877)
Decrease in payable for amount due to custodian, net		(2,522,916)
Net cash provided by (used for) financing activities		(7,463,987)
Net change in cash			1,456,533
Cash at beginning of period			285,679
Cash at end of period	$ 1,742,212		1,742,212
Supplemental disclosure of cash flow information
Cash paid for interest		$ 298	$ 298