DERIVATIVES - NOT DESIGNATED AS HEDGING INSTRUMENTS (Details) $ in Millions	12 Months Ended
Dec. 31, 2018 USD ($) $ / MillionCubicFeet $ / Barrel Bcf MMBbls	Dec. 31, 2017 USD ($) $ / MillionCubicFeet $ / Barrel Bcf MMBbls
Outstanding commodity derivatives contracts not designated as hedging instruments
Derivative instrument settlement period (within)	3 months
Crude Oil & NGLs \| Net sales
Outstanding commodity derivatives contracts not designated as hedging instruments
Unrealized gain (loss) on derivatives not designated as hedges	$ 184	$ (47)
Crude Oil & NGLs \| Long position
Outstanding commodity derivatives contracts not designated as hedging instruments
Commodity contracts Volume (MMBOE OR Bcf) \| MMBbls	61	61
Natural gas (in cubic feet) \| Net sales
Outstanding commodity derivatives contracts not designated as hedging instruments
Unrealized gain (loss) on derivatives not designated as hedges	$ 5	$ 1
Natural gas (in cubic feet) \| Short position
Outstanding commodity derivatives contracts not designated as hedging instruments
Commodity contracts Volume (MMBOE OR Bcf) \| Bcf	142	47
Not designated as hedging instruments \| Crude Oil & NGLs
Outstanding commodity derivatives contracts not designated as hedging instruments
Weighted average sales price (in dollars per share) \| $ / Barrel	58.81	57.38
Not designated as hedging instruments \| Natural gas (in cubic feet)
Outstanding commodity derivatives contracts not designated as hedging instruments
Weighted average sales price (in dollars per share) \| $ / MillionCubicFeet	3.18	2.73

The revenues derived from sales of oil or gas in each geographic area during the reporting period divided by the number of barrels of oil produced or thousands of cubic feet of gas produced.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher SEC
-Name Regulation S-K (SK)
-Number 229
-Section 1204
-Paragraph (b)
-Subparagraph (1)

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+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4CC
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL109998890-113959

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4C
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624171-113959

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