Statement of Changes in Shareholders' Equity (Unaudited) - USD ($)	Total	General Shares [Member]	Shares [Member]
Balance - Value at Dec. 31, 2014	$ 4,036,424,445	$ 736	$ 4,036,423,709
Balance - Shares at Dec. 31, 2014		40	219,400,000
Sale of Shares - Value	260,057,531		$ 260,057,531
Sale of Shares - Shares			14,400,000
Redemption of Shares - Value	(1,046,466,752)		$ (1,046,466,752)
Redemption of Shares - Shares			(58,600,000)
Net Increase (Decrease) due to Share Transactions, value	(786,409,221)		$ (786,409,221)
Net Increase (Decrease) due to Share Transactions, shares			(44,200,000)
Net Income (Loss)
Net Investment Income (Loss)	(14,420,376)	$ (2)	$ (14,420,374)
Net Realized Gain (Loss) on United States Treasury Obligations and Commodity Futures Contracts	(727,069,140)	(116)	(727,069,024)
Net Change in Unrealized Gain (Loss) on United States Treasury Obligations and Commodity Futures Contracts	647,797,996	103	647,797,893
Net Income (Loss)	(93,691,520)	(15)	(93,691,505)
Net Change in Shareholders' Equity, value	(880,100,741)	(15)	$ (880,100,726)
Net Change in Shareholders' Equity, shares			(44,200,000)
Balance - Value at Jun. 30, 2015	3,156,323,704	$ 721	$ 3,156,322,983
Balance - Shares at Jun. 30, 2015		40	175,200,000
Balance - Value at Mar. 31, 2015	2,991,731,711	$ 683	$ 2,991,731,028
Balance - Shares at Mar. 31, 2015		40	175,200,000
Sale of Shares - Value	168,251,432		$ 168,251,432
Sale of Shares - Shares			9,200,000
Redemption of Shares - Value	(163,571,029)		$ (163,571,029)
Redemption of Shares - Shares			(9,200,000)
Net Increase (Decrease) due to Share Transactions, value	4,680,403		$ 4,680,403
Net Income (Loss)
Net Investment Income (Loss)	(6,781,764)		(6,781,764)
Net Realized Gain (Loss) on United States Treasury Obligations and Commodity Futures Contracts	(301,640,755)	$ (27)	(301,640,728)
Net Change in Unrealized Gain (Loss) on United States Treasury Obligations and Commodity Futures Contracts	468,334,109	65	468,334,044
Net Income (Loss)	159,911,590	38	159,911,552
Net Change in Shareholders' Equity, value	164,591,993	38	164,591,955
Balance - Value at Jun. 30, 2015	3,156,323,704	$ 721	$ 3,156,322,983
Balance - Shares at Jun. 30, 2015		40	175,200,000
Balance - Value at Dec. 31, 2015	1,987,223,012	$ 534	$ 1,987,222,478
Balance - Shares at Dec. 31, 2015		40	148,800,000
Sale of Shares - Value	510,008,432		$ 510,008,432
Sale of Shares - Shares			36,200,000
Redemption of Shares - Value	(212,304,739)		$ (212,304,739)
Redemption of Shares - Shares			(16,200,000)
Net Increase (Decrease) due to Share Transactions, value	297,703,693		$ 297,703,693
Net Increase (Decrease) due to Share Transactions, shares			20,000,000
Net Income (Loss)
Net Investment Income (Loss)	(6,781,815)	$ (2)	$ (6,781,813)
Net Realized Gain (Loss) on United States Treasury Obligations and Commodity Futures Contracts	(265,280,041)	(69)	(265,279,972)
Net Change in Unrealized Gain (Loss) on United States Treasury Obligations and Commodity Futures Contracts	571,353,854	149	571,353,705
Net Income (Loss)	299,291,998	78	299,291,920
Net Change in Shareholders' Equity, value	596,995,691	78	$ 596,995,613
Net Change in Shareholders' Equity, shares			20,000,000
Balance - Value at Jun. 30, 2016	2,584,218,703	$ 612	$ 2,584,218,091
Balance - Shares at Jun. 30, 2016		40	168,800,000
Balance - Value at Mar. 31, 2016	1,997,317,386	$ 532	$ 1,997,316,854
Balance - Shares at Mar. 31, 2016		40	150,200,000
Sale of Shares - Value	394,710,038		$ 394,710,038
Sale of Shares - Shares			27,400,000
Redemption of Shares - Value	(119,877,533)		$ (119,877,533)
Redemption of Shares - Shares			(8,800,000)
Net Increase (Decrease) due to Share Transactions, value	274,832,505		$ 274,832,505
Net Increase (Decrease) due to Share Transactions, shares			18,600,000
Net Income (Loss)
Net Investment Income (Loss)	(3,483,909)	$ (1)	$ (3,483,908)
Net Realized Gain (Loss) on United States Treasury Obligations and Commodity Futures Contracts	(66,087,300)	(38)	(66,087,262)
Net Change in Unrealized Gain (Loss) on United States Treasury Obligations and Commodity Futures Contracts	381,640,021	119	381,639,902
Net Income (Loss)	312,068,812	80	312,068,732
Net Change in Shareholders' Equity, value	586,901,317	80	$ 586,901,237
Net Change in Shareholders' Equity, shares			18,600,000
Balance - Value at Jun. 30, 2016	$ 2,584,218,703	$ 612	$ 2,584,218,091
Balance - Shares at Jun. 30, 2016		40	168,800,000