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FAIR VALUE OF FINANCIAL INSTRUMENTS - Fair Value of Derivative Instruments (Details) - USD ($)
12 Months Ended
Dec. 31, 2019
Dec. 31, 2018
Commodity Contracts [Member] | Futures - Commodity Contracts [Member] | Assets [Member]    
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]    
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net $ (20,768,690) $ (67,021,257)