DERIVATIVE INSTRUMENTS AND PRICE RISK MANAGEMENT, Reconciliation between the gross assets and liabilities and the amounts reflected on the balance sheet (Details) - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets, Offsetting of Derivative Assets	$ 64,611,558	$ 153,906,231
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	64,611,558	153,906,231
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Assets, Offsetting of Derivative Liabilities		(579,070)
Gross Amounts Offset in the Balance Sheet, Offsetting of Derivative Liabilities		0
Net Amount of Assets Presented in Balance Sheet, Offsetting of Derivative Liabilities		(579,070)
Current Assets [Member]
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets, Offsetting of Derivative Assets	64,611,558	128,893,220
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	$ 64,611,558	128,893,220
Non Current Assets [Member]
Offsetting Assets [Line Items]
Gross Amounts of Recognized Assets, Offsetting of Derivative Assets		25,013,011
Gross Amounts Offset in the Balance Sheet, Offsetting of Derivative Assets		0
Net Amounts of Assets Presented in the Balance Sheet, Offsetting of Derivative Assets		25,013,011
Current Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Assets, Offsetting of Derivative Liabilities		0
Gross Amounts Offset in the Balance Sheet, Offsetting of Derivative Liabilities		0
Net Amount of Assets Presented in Balance Sheet, Offsetting of Derivative Liabilities		0
Non Current Liabilities [Member]
Offsetting Liabilities [Line Items]
Gross Amounts of Recognized Assets, Offsetting of Derivative Liabilities		(579,070)
Gross Amounts Offset in the Balance Sheet, Offsetting of Derivative Liabilities		0
Net Amount of Assets Presented in Balance Sheet, Offsetting of Derivative Liabilities		$ (579,070)