Goodwill (Narrative) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Mar. 31, 2020	Sep. 30, 2020
Goodwill [Line Items]
Goodwill		$ 1,845
Refining
Goodwill [Line Items]
Goodwill	$ 1,845	$ 1,845

Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13777-109266

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration