Quarterly report pursuant to Section 13 or 15(d)

DERIVATIVE INSTRUMENTS (Derivative Instruments in Financial Position) (Details)

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DERIVATIVE INSTRUMENTS (Derivative Instruments in Financial Position) (Details) - USD ($)
$ in Thousands
Jun. 30, 2020
Dec. 31, 2019
Derivatives, Fair Value [Line Items]    
Short-term derivative asset $ 53,188 $ 126,201
Long-term derivative asset 4,298 563
Short-term derivative liability (8,540) (303)
Long-term derivative liability (45,615) (53,135)
Total net asset derivative position 3,331 73,326
Commodity Contracts    
Derivatives, Fair Value [Line Items]    
Short-term derivative asset 53,188 125,383
Long-term derivative asset 4,298 0
Short-term derivative liability (8,540) (303)
Long-term derivative liability (45,615) (53,135)
Total net asset derivative position 3,331 71,945
Contingent consideration arrangement    
Derivatives, Fair Value [Line Items]    
Short-term derivative asset   818
Long-term derivative asset 0 563
Total contingent consideration derivative position $ 0 $ 1,381