Statements of Cash Flows (Unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities:
Net Income (Loss)	$ (205,196,621)	$ 299,291,998
Adjustments to reconcile net income (loss) to net cash provided by (used for) operating activities:
Cost of securities purchased	(2,800,286,118)	(4,292,552,464)
Proceeds from securities sold and matured	3,837,775,414	3,847,993,608
Cost of affiliated investments purchased	(1,908,713,427)
Proceeds from affiliated investments sold	1,693,717,967
Net accretion of discount on United States Treasury Obligations	(5,478,768)	(2,385,493)
Net realized (gain) loss on United States Treasury Obligations and Affiliated Investments	42,339	(1,263)
Net change in unrealized (gain) loss on United States Treasury Obligations, Affiliated Investments and Commodity Futures Contracts	(5,256,107)	(73,030,437)
Change in operating receivables and liabilities:
Dividends from affiliates	(7,443)
Variation margin	(30,793,505)	50,867,918
LME contracts	(4,803,422)	(18,126,339)
Management fee	(571,179)	237,248
Brokerage commissions and fees	(1,979)	(113)
Net cash provided by (used for) operating activities	570,427,151	(187,705,337)
Cash flows from financing activities:
Proceeds from purchases of Shares	142,251,533	510,008,432
Redemption of Shares	(708,495,377)	(212,304,739)
Net cash provided by (used for) financing activities	(566,243,844)	297,703,693
Net change in cash	4,183,307	109,998,356
Cash at beginning of period	5,015,157	92,092,936
Cash at end of period	9,198,464	202,091,292
Supplemental disclosure of cash flow information
Cash paid for interest	$ 62,945	$ 104,245