Variable Interest Entities (Details) - USD ($) $ in Millions	Dec. 31, 2016	May 31, 2016
Crowley Coastal Partners
Schedule of Equity Method Investments [Line Items]
Maximum loss exposure, amount	$ 489
Equity method investments, ownership percentage	50.00%	50.00%
MarkWest Utica EMG
Schedule of Equity Method Investments [Line Items]
Maximum loss exposure, amount	$ 2,220
Equity method investments, ownership percentage	56.00%
Ohio Gathering
Schedule of Equity Method Investments [Line Items]
Equity method investments, ownership percentage	34.00%

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66011266&loc=d3e33918-111571

+ Details

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Balance Type:	na
Period Type:	instant

- Definition

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.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

The reporting entity's maximum amount of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph b
-URI http://asc.fasb.org/extlink&oid=64801991&loc=d3e5728-111685

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=64801991&loc=d3e5747-111685

+ Details

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Balance Type:	credit
Period Type:	instant

- Details

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- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=mpc_MarkWestUticaEMGMember
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Data Type:	na
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- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=mpc_OhioGatheringCompanyLLCMember
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