Statements of Cash Flows - USD ($)	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Cash flows from operating activities:
Net Income (Loss)	$ 205,956,914	$ (290,387,802)	$ 71,185,537
Adjustments to reconcile net income (loss) to net cash provided by (used in) operating activities:
Cost of securities purchased	(3,654,657,512)	(6,473,560,355)	(6,226,946,742)
Proceeds from securities sold and matured	4,633,155,039	6,739,557,713	6,805,695,866
Cost of affiliated investments purchased	(3,634,032,756)	(3,916,848,412)	(4,198,801,266)
Proceeds from affiliated investments sold	3,261,472,332	3,839,913,024	4,011,837,165
Net accretion of discount on United States Treasury Obligations	(28,578,301)	(41,381,034)	(14,035,908)
Net realized (gain) loss on United States Treasury Obligations and Affiliated Investments	(54,902)	44,353	44,293
Net change in unrealized (gain) loss on United States Treasury Obligations, Affiliated Investments and Commodity Futures Contracts	(34,694,600)	54,104,708	(10,588,043)
Change in operating assets and liabilities:
Dividends from affiliates	(79,139)	(174,130)	(51,445)
Variation margin - Commodity Futures Contracts	4,539,464	14,515,805	(10,540,724)
LME Commodity Futures Contracts	(23,761,626)	29,026,856	(506,436)
Management fees	(448,209)	(181,646)	(189,346)
Brokerage commissions and fees	3,189	(2,741)	(2,235)
Other receivables	17,077	(17,077)
Net cash provided by (used in) operating activities	728,836,970	(45,390,738)	427,100,716
Cash flows from financing activities:
Distributions paid to shareholders	(22,743,178)	(24,584,320)
Proceeds from purchases of Shares	120,198,453	1,287,584,068	641,160,206
Redemption of Shares	(807,331,962)	(1,242,508,857)	(1,067,336,515)
Increase (decrease) in payable for amount due to custodian	(18,960,283)	18,960,283
Net cash provided by (used in) financing activities	(728,836,970)	39,451,174	(426,176,309)
Net change in cash		(5,939,564)	924,407
Cash at beginning of period		5,939,564	5,015,157
Cash at end of period			5,939,564
Supplemental disclosure of cash flow information
Cash paid for interest	$ 312,961	$ 782,292	$ 68,451

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