Quarterly report pursuant to Section 13 or 15(d)

DERIVATIVE INSTRUMENTS (Net (Loss) Gain on Derivative Instruments) (Details)

v3.19.1
DERIVATIVE INSTRUMENTS (Net (Loss) Gain on Derivative Instruments) (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2019
Mar. 31, 2018
Derivative [Line Items]    
Net loss on natural gas, oil, and NGL derivatives $ (20,045) $ (16,529)
Natural gas derivatives    
Derivative [Line Items]    
Net loss on natural gas, oil, and NGL derivatives (16,431) (9,696)
Oil derivatives    
Derivative [Line Items]    
Net loss on natural gas, oil, and NGL derivatives (454) (9,147)
Natural gas liquids derivatives    
Derivative [Line Items]    
Net loss on natural gas, oil, and NGL derivatives $ (3,160) $ 2,314