Derivative Financial Instruments (Schedule Of Derivative Financial Instruments Included In The Consolidated Balance Sheets) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Derivatives Fair Value [Line Items]
Fair value of derivative assets	$ 643	$ 50
Fair value of derivative liabilities	5	31
Commodity Derivatives [Member] \| Other Current Assets [Member]
Derivatives Fair Value [Line Items]
Fair value of derivative assets	616	49
Commodity Derivatives [Member] \| Other Long-Term Assets [Member]
Derivatives Fair Value [Line Items]
Fair value of derivative assets	27	1
Commodity Derivatives [Member] \| Other Current Liabilities [Member]
Derivatives Fair Value [Line Items]
Fair value of derivative liabilities		30
Commodity Derivatives [Member] \| Other Long-Term Liabilities [Member]
Derivatives Fair Value [Line Items]
Fair value of derivative liabilities	$ 5	$ 1

Fair value as of the balance sheet date of derivative instrument not designated as hedging instrument and classified as an asset.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4B
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5624163-113959

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- Definition

Fair value as of the balance sheet date of derivative instrument not designated as hedging instrument and classified as a liability.

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- Definition

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