Quarterly report pursuant to Section 13 or 15(d)

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

v3.19.2
DERIVATIVE INSTRUMENTS (Net (Loss) Gain on Derivative Instruments) (Details) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2019
Jun. 30, 2018
Jun. 30, 2019
Jun. 30, 2018
Derivative [Line Items]        
Net gain (loss) on natural gas, oil, and NGLs derivatives $ 171,140 $ (70,545) $ 151,095 $ (87,074)
Natural gas derivatives        
Derivative [Line Items]        
Net gain (loss) on natural gas, oil, and NGLs derivatives 152,475 (31,194) 136,044 (40,890)
Oil derivatives        
Derivative [Line Items]        
Net gain (loss) on natural gas, oil, and NGLs derivatives 11,871 (24,419) 11,417 (33,566)
NGL derivatives        
Derivative [Line Items]        
Net gain (loss) on natural gas, oil, and NGLs derivatives $ 6,794 $ (14,932) $ 3,634 $ (12,618)