The aggregate amount of write-downs for impairments recognized during the period for long lived assets held for use (including those held for disposal by means other than sale).

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Name:	us-gaap_ImpairmentOfLongLivedAssetsHeldForUse
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Impairments (Long-lived Assets) (Details) - Impairment expense - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2021	Sep. 30, 2020
Finite-Lived Intangible Assets [Line Items]
Long-lived assets impairment	$ 0	$ 369		$ 0	$ 886
Refining & Marketing
Finite-Lived Intangible Assets [Line Items]
Long-lived assets impairment		342	$ 142
MPLX LP \| Midstream
Finite-Lived Intangible Assets [Line Items]
Long-lived assets impairment		$ 27	$ 350