Fair value of liability associated with 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.

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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. Includes assets not subject to a master netting arrangement and not elected to be offset.

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The average floor rate on a group of price risk derivatives such as floors or collars. A payment or receipt is triggered if the market rate falls below the floor rate on the contract.

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The cap rate on a price risk derivative such as a cap or collar. A payment or receipt is triggered if the market rate exceeds the cap rate on the contract.

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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.

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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.

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Fair value, after the 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 not subject to a master netting arrangement and not elected to be offset.

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Fair value of asset associated with 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.

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Nominal energy measure used to calculate payments on a derivative instrument.

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Nominal mass used to calculate payments on a derivative instrument.

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Nominal volume used to calculate payments on a derivative instrument.

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Fixed price related to the price risk swap derivative.

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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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FINANCIAL INSTRUMENTS (Unsettled Derivatives) (Details) lb in Millions, bbl in Millions, MMBTU in Millions, $ in Millions		36 Months Ended	50 Months Ended
	Dec. 31, 2016 USD ($) lb	Dec. 31, 2020 $ / bbl bbl	Dec. 31, 2020 MMBTU $ / bbl bbl	Dec. 31, 2020 $ / MMBTU	Dec. 31, 2015 USD ($)
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 146				$ 20
Derivative Liability, Fair Value, Gross Liability	58				92
Derivative Liability, Fair Value, Gross Asset	14				6
Derivative Asset, Fair Value, Gross Liability	14				6
Derivative Asset	132				14
Derivative Liability	44				86
Trade accounts receivable [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset	119				9
Derivative Liability	13				51
Other current assets [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset	7				0
Derivative Liability	0				0
Accounts Payable and Accrued Liabilities
Derivatives, Fair Value [Line Items]
Derivative Asset	6				5
Derivative Liability	31				35
Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	9				1
Derivative Liability, Fair Value, Gross Liability	2				11
Derivative Liability, Fair Value, Gross Asset	2				1
Derivative Asset, Fair Value, Gross Liability	2				1
Derivative Asset	7				0
Derivative Liability	0				10
Embedded Derivative Financial Instruments [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	137				19
Derivative Liability, Fair Value, Gross Liability	56				81
Derivative Liability, Fair Value, Gross Asset	12				5
Derivative Asset, Fair Value, Gross Liability	12				5
Derivative Asset	125				14
Derivative Liability	44				76
Designated as Hedging Instrument [Member] \| Commodity Contract [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	9				1
Derivative Liability, Fair Value, Gross Liability	$ 2				11
Derivative, Nonmonetary Notional Amount, Mass \| lb	42
Derivatives Not Designated as Hedging Instruments [Member] \| Embedded Derivative Financial Instruments [Member]
Derivatives, Fair Value [Line Items]
Derivative Asset, Fair Value, Gross Asset	$ 137				19
Derivative Liability, Fair Value, Gross Liability	$ 56				$ 81
Derivatives Not Designated as Hedging Instruments [Member] \| Forward Contracts [Member]
Derivatives, Fair Value [Line Items]
Derivative, Nonmonetary Notional Amount, Mass \| lb	3
Scenario, Forecast [Member]
Derivatives, Fair Value [Line Items]
Derivative, Nonmonetary Notional Amount, Volume \| bbl		5.2	19.4
Derivative, Nonmonetary Notional Amount, Energy Measure \| MMBTU			28.9
Derivative, Swap Type, Fixed Price		56.04	56.04	3.1445
Derivative, Average Floor Price \| $ / bbl		50.00	50.00
Derivative, Cap Price \| $ / bbl		63.69	63.69