Quarterly report pursuant to Section 13 or 15(d)

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

v3.20.1
DERIVATIVE INSTRUMENTS (Net (Loss) Gain on Derivative Instruments) (Details) - USD ($)
$ in Thousands
 3 Months Ended
Mar. 31, 2020
Mar. 31, 2019
Derivative [Line Items]    
Net gain (loss) on natural gas, oil and NGL derivatives $ 98,266 $ (20,045)
Natural gas derivatives    
Derivative [Line Items]    
Net gain (loss) on natural gas, oil and NGL derivatives 45,853 (16,431)
Oil derivatives    
Derivative [Line Items]    
Net gain (loss) on natural gas, oil and NGL derivatives 52,874 (454)
NGL derivatives    
Derivative [Line Items]    
Net gain (loss) on natural gas, oil and NGL derivatives 920 (3,160)
Contingent consideration arrangement    
Derivative [Line Items]    
Net gain (loss) on natural gas, oil and NGL derivatives $ (1,381) $ 0