Statement of Changes in Shareholders' Equity - USD ($)	Total	General Shares [Member]	Shares [Member]
Balance - Value at Dec. 31, 2016	$ 2,557,464,539	$ 633	$ 2,557,463,906
Balance - Shares at Dec. 31, 2016		40	161,600,000
Purchases of Shares - Value	701,045,632		$ 701,045,632
Purchases of Shares - Shares			43,600,000
Redemption of Shares - Value	(1,067,336,515)		$ (1,067,336,515)
Redemption of Shares - Shares			(69,200,000)
Net Increase (Decrease) due to Share Transactions, value	(366,290,883)		$ (366,290,883)
Net Increase (Decrease) due to Share Transactions, shares			(25,600,000)
Net Income (Loss)
Net Investment Income (Loss)	(1,457,317)	$ (1)	$ (1,457,316)
Net Realized Gain (Loss) on United States Treasury Obligations, Affiliated Investments and Commodity Futures Contracts	58,294,421	26	58,294,395
Net Change in Unrealized Gain (Loss) on United States Treasury Obligations, Affiliated Investments and Commodity Futures Contracts	14,348,433	7	14,348,426
Net Income (Loss)	71,185,537	32	71,185,505
Net Change in Shareholders' Equity, value	(295,105,346)	32	$ (295,105,378)
Net Change in Shareholders' Equity, shares			(25,600,000)
Balance - Value at Dec. 31, 2017	2,262,359,193	$ 665	$ 2,262,358,528
Balance - Shares at Dec. 31, 2017		40	136,000,000
Purchases of Shares - Value	1,227,698,642		$ 1,227,698,642
Purchases of Shares - Shares			71,600,000
Redemption of Shares - Value	(1,242,508,857)		$ (1,242,508,857)
Redemption of Shares - Shares			(73,800,000)
Net Increase (Decrease) due to Share Transactions, value	(14,810,215)		$ (14,810,215)
Net Increase (Decrease) due to Share Transactions, shares			(2,200,000)
Return of Capital Distributions	(24,584,320)	$ (8)	$ (24,584,312)
Net Income (Loss)
Net Investment Income (Loss)	25,051,062	8	25,051,054
Net Realized Gain (Loss) on United States Treasury Obligations, Affiliated Investments and Commodity Futures Contracts	43,580,448	13	43,580,435
Net Change in Unrealized Gain (Loss) on United States Treasury Obligations, Affiliated Investments and Commodity Futures Contracts	(359,019,312)	(100)	(359,019,212)
Net Income (Loss)	(290,387,802)	(79)	(290,387,723)
Net Change in Shareholders' Equity, value	(329,782,337)	(87)	$ (329,782,250)
Net Change in Shareholders' Equity, shares			(2,200,000)
Balance - Value at Dec. 31, 2018	1,932,576,856	$ 578	$ 1,932,576,278
Balance - Shares at Dec. 31, 2018		40	133,800,000
Purchases of Shares - Value	120,198,453		$ 120,198,453
Purchases of Shares - Shares			7,800,000
Redemption of Shares - Value	(807,331,962)		$ (807,331,962)
Redemption of Shares - Shares			(52,000,000)
Net Increase (Decrease) due to Share Transactions, value	(687,133,509)		$ (687,133,509)
Net Increase (Decrease) due to Share Transactions, shares			(44,200,000)
Return of Capital Distributions	(22,743,178)	$ (10)	$ (22,743,168)
Net Income (Loss)
Net Investment Income (Loss)	22,272,174	10	22,272,164
Net Realized Gain (Loss) on United States Treasury Obligations, Affiliated Investments and Commodity Futures Contracts	(108,348,865)	(35)	(108,348,830)
Net Change in Unrealized Gain (Loss) on United States Treasury Obligations, Affiliated Investments and Commodity Futures Contracts	292,033,605	95	292,033,510
Net Income (Loss)	205,956,914	70	205,956,844
Net Change in Shareholders' Equity, value	(503,919,773)	60	$ (503,919,833)
Net Change in Shareholders' Equity, shares			(44,200,000)
Balance - Value at Dec. 31, 2019	$ 1,428,657,083	$ 638	$ 1,428,656,445
Balance - Shares at Dec. 31, 2019		40	89,600,000