Additional Valuation Information - Summary of the Tiered Valuation Input Levels (Detail) - USD ($)	Sep. 30, 2019	Dec. 31, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
United States Treasury Obligations	$ 1,120,058,993	$ 1,614,425,920
Exchange-Traded Fund	250,466,130	250,145,856
Money Market Mutual Fund	66,147,555	144,939,067
Total Investments in Securities	1,436,672,678	2,009,510,843
Commodity Futures Contracts, Appreciation	24,685,772	9,428,661
Commodity Futures Contracts, Depreciation	(86,511,485)	(253,228,835)
Commodity Futures Contracts	(61,825,713)	(243,800,174)
Total Investments	1,374,846,965	1,765,710,669
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Exchange-Traded Fund	250,466,130	250,145,856
Money Market Mutual Fund	66,147,555	144,939,067
Total Investments in Securities	316,613,685	395,084,923
Commodity Futures Contracts, Appreciation	24,685,772	9,428,661
Commodity Futures Contracts, Depreciation	(86,511,485)	(253,228,835)
Commodity Futures Contracts	(61,825,713)	(243,800,174)
Total Investments	254,787,972	151,284,749
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
United States Treasury Obligations	1,120,058,993	1,614,425,920
Total Investments in Securities	1,120,058,993	1,614,425,920
Total Investments	$ 1,120,058,993	$ 1,614,425,920