Service Providers and Related Party Agreements - Additional Information (Detail) - USD ($)		6 Months Ended
	Feb. 26, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015	Dec. 31, 2014
Related Party Transaction [Line Items]
Management fee percentage per annum of daily net asset		0.85%
United States Treasury Obligations, at fair value (cost $2,383,864,387 and $1,936,918,775, respectively)		$ 2,384,228,085		$ 1,936,908,405	$ 4,977,853,691
Cash held by commodity broker					$ 745,587,142
Cash transfer to Commodity Broker to satisfy variation margin requirements			$ (584,258,422)
Bank of New York Mellon [Member]
Related Party Transaction [Line Items]
Cash transferred to custodian	$ 784,986,543
United States Treasury Obligations transferred to custodian	3,488,957,734
Commodity Broker [Member]
Related Party Transaction [Line Items]
United States Treasury Obligations transferred to Commodity Broker	1,078,892,100
Cash transfer to Commodity Broker to satisfy variation margin requirements	$ 584,258,422
Through June 20, 2017 [Member]
Related Party Transaction [Line Items]
Management fee waive on net advisory fees, percentage		100.00%