Statement of Changes in Shareholders' Equity (Unaudited) - USD ($)	Total	General Shares [Member]	Shares [Member]
Balance - Value at Dec. 31, 2017	$ 641,751,747	$ 750	$ 641,750,997
Balance - Shares at Dec. 31, 2017		40	34,200,000
Purchases of Shares - Value	130,086,879		$ 130,086,879
Purchases of Shares - Shares			6,800,000
Redemption of Shares - Value	(22,661,544)		$ (22,661,544)
Redemption of Shares - Shares			(1,200,000)
Net Increase (Decrease) due to Share Transactions, value	107,425,335		$ 107,425,335
Net Increase (Decrease) due to Share Transactions, shares			5,600,000
Net Income (Loss)
Net Investment Income (Loss)	674,377	$ (2)	$ 674,379
Net Realized Gain (Loss) on United States Treasury Obligations, Affiliated Investments and Commodity Futures Contracts	(17,711,457)	57	(17,711,514)
Net Change in Unrealized Gain (Loss) on United States Treasury Obligations, Affiliated Investments and Commodity Futures Contracts	16,416,939	(53)	16,416,992
Net Income (Loss)	(620,141)	2	(620,143)
Net Change in Shareholders' Equity, value	106,805,194	2	$ 106,805,192
Net Change in Shareholders' Equity, shares			5,600,000
Balance - Value at Mar. 31, 2018	748,556,941	$ 752	$ 748,556,189
Balance - Shares at Mar. 31, 2018		40	39,800,000
Balance - Value at Dec. 31, 2018	494,781,661	$ 678	$ 494,780,983
Balance - Shares at Dec. 31, 2018		40	29,200,000
Purchases of Shares - Value	16,951,145		$ 16,951,145
Purchases of Shares - Shares			1,000,000
Redemption of Shares - Value	(43,494,213)		$ (43,494,213)
Redemption of Shares - Shares			(2,600,000)
Net Increase (Decrease) due to Share Transactions, value	(26,543,068)		$ (26,543,068)
Net Increase (Decrease) due to Share Transactions, shares			(1,600,000)
Net Income (Loss)
Net Investment Income (Loss)	1,743,850	$ 2	$ 1,743,848
Net Realized Gain (Loss) on United States Treasury Obligations, Affiliated Investments and Commodity Futures Contracts	(13,815,711)	(19)	(13,815,692)
Net Change in Unrealized Gain (Loss) on United States Treasury Obligations, Affiliated Investments and Commodity Futures Contracts	(1,169,806)	(1)	(1,169,805)
Net Income (Loss)	(13,241,667)	(18)	(13,241,649)
Net Change in Shareholders' Equity, value	(39,784,735)	(18)	$ (39,784,717)
Net Change in Shareholders' Equity, shares			(1,600,000)
Balance - Value at Mar. 31, 2019	$ 454,996,926	$ 660	$ 454,996,266
Balance - Shares at Mar. 31, 2019		40	27,600,000