Service Providers and Related Party Agreements - Additional Information (Detail) - USD ($)		12 Months Ended
	Feb. 26, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Related Party Transaction [Line Items]
Management fee percentage per annum of daily net asset		0.75%
Managing owner waived fees		$ 25,204
Compensation for service to advisors		0
United States Treasury Obligations		$ 846,158,812	$ 1,077,913,905	$ 1,006,974,568
Cash held by commodity broker				$ 18,108,522
Cash transfer to Commodity Broker to satisfy variation margin requirements			$ 55,249,567
Bank of New York Mellon [Member]
Related Party Transaction [Line Items]
Cash transferred to custodian	$ 55,000,000
United States Treasury Obligations transferred to custodian	1,074,986,895
Commodity Broker [Member]
Related Party Transaction [Line Items]
Cash transfer to Commodity Broker to satisfy variation margin requirements	55,249,567
United States Treasury Obligations transferred to Commodity Broker	$ 32,000,000