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DERIVATIVE INSTRUMENTS - Unobservable Inputs Narrative (Details) - Fair Value, Inputs, Level 3 [Member]
6 Months Ended
Jun. 30, 2017
Minimum [Member]  
Derivative Instruments and Hedging Activities Disclosures [Line Items]  
Percentage of exit price premiums related to derivative contracts 2.00%
Maximum [Member]  
Derivative Instruments and Hedging Activities Disclosures [Line Items]  
Percentage of exit price premiums related to derivative contracts 19.00%