Quarterly report pursuant to Section 13 or 15(d)

DERIVATIVE INSTRUMENTS AND PRICE RISK MANAGEMENT - Reconciliation between the gross assets and liabilities and the amounts reflected on the balance sheet (Details)

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DERIVATIVE INSTRUMENTS AND PRICE RISK MANAGEMENT - Reconciliation between the gross assets and liabilities and the amounts reflected on the balance sheet (Details) - USD ($)
Mar. 31, 2018
Dec. 31, 2017
Offsetting Assets [Line Items]    
Current liabilities $ (26,796,245) $ (18,681,891)
Noncurrent liabilities (15,523,889) (11,496,929)
Total derivative liabilities (42,320,134) (30,178,820)
Gross Amounts of Recognized Assets, Offsetting of Derivative Assets 0 0
Gross Amounts Offset in the Balance Sheet, Offsetting of Derivative Assets 0 0
Net Amounts of Assets Presented in the Balance Sheet, Offsetting of Derivative Assets 0 0
Gross Amounts of Recognized Assets, Offsetting of Derivative Liabilities (42,326,872) (30,178,820)
Gross Amounts Offset in the Balance Sheet, Offsetting of Derivative Liabilities 6,738 0
Net Amounts of Assets Presented in the Balance Sheet, Offsetting of Derivative Liabilities (42,320,134) (30,178,820)
Current Assets    
Offsetting Assets [Line Items]    
Gross Amounts of Recognized Assets, Offsetting of Derivative Assets 0 0
Gross Amounts Offset in the Balance Sheet, Offsetting of Derivative Assets 0 0
Net Amounts of Assets Presented in the Balance Sheet, Offsetting of Derivative Assets 0 0
Noncurrent Assets    
Offsetting Assets [Line Items]    
Gross Amounts of Recognized Assets, Offsetting of Derivative Assets 0 0
Gross Amounts Offset in the Balance Sheet, Offsetting of Derivative Assets 0 0
Net Amounts of Assets Presented in the Balance Sheet, Offsetting of Derivative Assets 0 0
Current Liabilities    
Offsetting Assets [Line Items]    
Gross Amounts of Recognized Assets, Offsetting of Derivative Liabilities (26,796,245) (18,681,891)
Gross Amounts Offset in the Balance Sheet, Offsetting of Derivative Liabilities 0 0
Net Amounts of Assets Presented in the Balance Sheet, Offsetting of Derivative Liabilities (26,796,245) (18,681,891)
Noncurrent Liabilities    
Offsetting Assets [Line Items]    
Gross Amounts of Recognized Assets, Offsetting of Derivative Liabilities (15,530,627) (11,496,929)
Gross Amounts Offset in the Balance Sheet, Offsetting of Derivative Liabilities 6,738 0
Net Amounts of Assets Presented in the Balance Sheet, Offsetting of Derivative Liabilities (15,523,889) (11,496,929)
Swap Contracts | Current Liabilities    
Offsetting Assets [Line Items]    
Current liabilities (26,796,245) (18,681,891)
Swap Contracts | Noncurrent Liabilities    
Offsetting Assets [Line Items]    
Noncurrent liabilities $ (15,523,889) $ (11,496,929)