DERIVATIVE INSTRUMENTS (Derivative Instruments in Financial Position) (Details) - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Derivatives, Fair Value [Line Items]
Total short-term derivative instruments - asset	$ 134,571	$ 21,352
Total long-term derivative instruments - asset	23,419	0
Total short-term derivative instruments - liability	429	20,401
Total long-term derivative instruments - liability	72,040	13,992
Commodity derivative instruments
Derivatives, Fair Value [Line Items]
Total short-term derivative instruments - asset	134,511	21,352
Total long-term derivative instruments - asset	23,375	0
Contingent consideration arrangement
Derivatives, Fair Value [Line Items]
Total short-term derivative instruments - asset	60
Total long-term derivative instruments - asset	$ 44	$ 0

Fair value, after the effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, expected to be settled within one year or normal operating cycle, if longer. Includes assets not subject to a master netting arrangement and not elected to be offset.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

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- Definition

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