Goodwill (Narrative) (Details) $ in Millions	3 Months Ended
Mar. 31, 2020 USD ($)
Goodwill [Line Items]
Goodwill, impairment loss	$ 1,845
Refining
Goodwill [Line Items]
Goodwill, impairment loss	$ 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
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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