Statements of Cash Flows (Unaudited) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Cash Flows from Operating Activities
Net decrease in net assets resulting from operations	$ (169,145,849)	$ (145,069,299)	$ (174,310,680)	$ (95,285,111)	$ (379,375,571)	[1]
Adjustments to reconcile net decrease in net assets resulting from operations to net cash provided by (used in) operating activities:
Purchases of short-term investments			(3,391,523,148)	(3,907,427,152)
Sales/maturities of short-term investments			3,349,547,641	4,086,531,783
Accretion of discount			(176,020)	(411,765)
Net realized gain on short-term investments	(14,776)	(8,576)	(29,232)	(29,121)
Net change in unrealized appreciation/depreciation on short-term investments	(37,597)	0	(53,611)	0
Change in operating assets and liabilities:
Receivable for variation margin on open futures contracts			(6,562,418)	0
Payable for variation margin on open futures contracts			(7,717,674)	22,049,781
Payable for investment securities purchased			88,996,424	0
Due to brokers			(323,566)	0
Sponsor’s fees payable			(62,622)	(109,799)
Net cash provided by (used in) operating activities			(142,214,906)	105,318,616
Cash Flows from Financing Activities
Contributions for Shares issued			193,399,406	252,340,901
Distributions for Shares redeemed			(59,602,588)	(348,984,655)
Net cash provided by (used in) financing activities			133,796,818	(96,643,754)
Net increase (decrease) in cash and cash equivalents			(8,418,088)	8,674,862
Cash and Cash Equivalents
Beginning of period			12,009,679	11,089,091	11,089,091
End of period	$ 3,591,591	$ 19,763,953	$ 3,591,591	$ 19,763,953	$ 12,009,679

[1] Previously reported as "Statements of Changes in Shareholders' Capital." Please refer to Note 2A.