Statements of Cash Flows (Unaudited) - USD ($)	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities:
Net Income (Loss)	$ 156,790,892	$ (205,196,621)
Adjustments to reconcile net income (loss) to net cash provided by (used for) operating activities:
Cost of securities purchased	(4,070,548,698)	(2,800,286,118)
Proceeds from securities sold and matured	3,319,795,140	3,837,775,414
Cost of affiliated investments purchased	(1,696,531,792)	(1,908,713,427)
Proceeds from affiliated investments sold	1,616,363,400	1,693,717,967
Net accretion of discount on United States Treasury Obligations	(19,033,572)	(5,478,768)
Net realized (gain) loss on United States Treasury Obligations and Affiliated Investments	5,564	42,339
Net change in unrealized (gain) loss on United States Treasury Obligations, Affiliated Investments and Commodity Futures Contracts	48,331,922	(5,256,107)
Change in operating assets and liabilities:
Dividends from affiliates	(128,995)	(7,443)
Variation margin - Commodity Futures Contracts	(20,483,083)	(30,793,505)
LME Commodity Futures Contracts	3,267,594	(4,803,422)
Management fees	619,475	(571,179)
Brokerage commissions and fees	(2,779)	(1,979)
Net cash provided by (used for) operating activities	(661,554,932)	570,427,151
Cash flows from financing activities:
Proceeds from purchases of Shares	1,124,258,264	142,251,533
Redemption of Shares	(468,642,896)	(708,495,377)
Net cash provided by (used for) financing activities	655,615,368	(566,243,844)
Net change in cash	(5,939,564)	4,183,307
Cash at beginning of period	5,939,564	5,015,157
Cash at end of period	0	9,198,464
Supplemental disclosure of cash flow information
Cash paid for interest	$ 18,237	$ 62,945