DERIVATIVE AND HEDGING ACTIVITIES - (Details) $ in Thousands	Dec. 31, 2018 USD ($) item	Dec. 31, 2017 USD ($) item
Derivative and hedging activities
Asset derivative contracts \| $	$ 69,717	$ 677
Liability derivative contracts \| $	(12,907)	(26,999)
Derivatives not designated as hedging contracts
Derivative and hedging activities
Asset derivative contracts \| $	69,717	677
Liability derivative contracts \| $	$ (12,907)	$ (26,999)
Derivatives not designated as hedging contracts \| Commodity contracts
Derivative and hedging activities
Number of open commodity derivative contracts	86	34
Derivatives not designated as hedging contracts \| Commodity contracts \| Current assets - receivables from derivative contracts
Derivative and hedging activities
Asset derivative contracts \| $	$ 57,280	$ 677
Derivatives not designated as hedging contracts \| Commodity contracts \| Other noncurrent assets - receivables from derivative contracts
Derivative and hedging activities
Asset derivative contracts \| $	12,437
Derivatives not designated as hedging contracts \| Commodity contracts \| Current liabilities - liabilities from derivative contracts
Derivative and hedging activities
Liability derivative contracts \| $	(3,768)	(19,248)
Derivatives not designated as hedging contracts \| Commodity contracts \| Other noncurrent liabilities - liabilities from derivative contracts
Derivative and hedging activities
Liability derivative contracts \| $	$ (9,139)	$ (7,751)
Derivatives not designated as hedging contracts \| Commodity contracts \| Collars \| Natural gas
Derivative and hedging activities
Number of open commodity derivative contracts	9	3
Derivatives not designated as hedging contracts \| Commodity contracts \| Collars \| Crude oil
Derivative and hedging activities
Number of open commodity derivative contracts	31	19
Derivatives not designated as hedging contracts \| Commodity contracts \| Basis Swap \| Natural gas
Derivative and hedging activities
Number of open commodity derivative contracts	7
Derivatives not designated as hedging contracts \| Commodity contracts \| Basis Swap \| Crude oil
Derivative and hedging activities
Number of open commodity derivative contracts	26	12
Derivatives not designated as hedging contracts \| Commodity contracts \| Swaps \| Natural gas liquids
Derivative and hedging activities
Number of open commodity derivative contracts	6
Derivatives not designated as hedging contracts \| Commodity contracts \| Put options \| Crude oil
Derivative and hedging activities
Number of open commodity derivative contracts	2
Derivatives not designated as hedging contracts \| Commodity contracts \| Call option \| Crude oil
Derivative and hedging activities
Number of open commodity derivative contracts	4
Derivatives not designated as hedging contracts \| Commodity contracts \| WTI NYMEX Roll \| Crude oil
Derivative and hedging activities
Number of open commodity derivative contracts	1

Fair value, before 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. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (a),(c)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624163-113959

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=82849420&loc=SL20226000-175313

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4D
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=82924980&loc=SL51823488-111719

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Fair value, before effects of master netting arrangements, of a financial liability or 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. Includes liabilities elected not to be offset. Excludes liabilities not subject to a master netting arrangement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 20
-Section 50
-Paragraph 4D
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=82924980&loc=SL51823488-111719

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (a),(c)
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5624163-113959

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=82849420&loc=SL20226000-175313

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The number of derivative instruments of a particular group held by the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=84234895&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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