Statements of Income and Expenses - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income
Interest Income	$ 41,701,196	$ 14,035,908	$ 6,308,729
Dividends from Affiliates	6,595,643	2,600,473	139,113
Total Income	48,296,839	16,636,381	6,447,842
Expenses
Management Fees	22,341,142	17,965,282	19,189,799
Brokerage Commissions and Fees	574,590	492,416	759,634
Interest Expense	782,292	68,451	141,261
Total Expenses	23,698,024	18,526,149	20,090,694
Less: Waivers	(452,247)	(432,451)	(68,552)
Net Expenses	23,245,777	18,093,698	20,022,142
Net Investment Income (Loss)	25,051,062	(1,457,317)	(13,574,300)
Net Realized Gain (Loss) on
United States Treasury Obligations	(44,353)	(44,293)	19,938
Commodity Futures Contracts	43,624,801	58,338,714	(72,730,527)
Net Realized Gain (Loss)	43,580,448	58,294,421	(72,710,589)
Net Change in Unrealized Gain (Loss) on
United States Treasury Obligations	46,869	(40,787)	(56,173)
Affiliated Investments	403,308	(247,678)
Commodity Futures Contracts	(359,469,489)	14,636,898	452,312,410
Net Change in Unrealized Gain (Loss)	(359,019,312)	14,348,433	452,256,237
Net Realized and Net Change in Unrealized Gain (Loss) on United States Treasury Obligations, Affiliated Investments and Commodity Futures Contracts	(315,438,864)	72,642,854	379,545,648
Net Income (Loss)	$ (290,387,802)	$ 71,185,537	$ 365,971,348