Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Cash flows from operating activities:
Net Income (Loss)	$ (99,206,397)	$ (12,776,814)
Adjustments to reconcile net income (loss) to net cash provided by (used for) operating activities:
Cost of securities purchased	(1,161,444,080)	(1,912,773,559)
Proceeds from securities sold and matured	1,718,884,808	1,937,000,001
Cost of affiliated investments purchased	(1,281,979,033)
Proceeds from affiliated investments sold	1,067,092,340
Net accretion of discount on United States Treasury Obligations	(2,580,166)	(892,403)
Net realized (gain) loss on United States Treasury Obligations and Affiliated Investments	29,664	(631)
Net change in unrealized (gain) loss on United States Treasury Obligations, Affiliated Investments and Commodity Futures Contracts	(10,023,252)	(48,772,160)
Change in operating receivables and liabilities:
Dividends from affiliates	7,169
Variation margin	(16,420,054)	21,761,688
LME contracts	(1,787,591)	(21,657,176)
Management fee	(118,472)	(129,960)
Brokerage commissions and fees	(707)	182
Net cash provided by (used for) operating activities	212,454,229	(38,240,832)
Cash flows from financing activities:
Proceeds from purchases of Shares	136,024,461	115,298,394
Redemption of Shares	(353,493,847)	(92,427,206)
Net cash provided by (used for) financing activities	(217,469,386)	22,871,188
Net change in cash	(5,015,157)	(15,369,644)
Cash at beginning of period	5,015,157	92,092,936
Cash at end of period		76,723,292
Supplemental disclosure of cash flow information
Cash paid for interest	$ 28,061	$ 96,887