XML 107 R88.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Equity (ATM Program) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
Stockholders Equity [Line Items] |  |  |
Common Stock, Monetary Value of Shares Authorized | $ 1,700 |  |
Units issued |  | 14,129,589 | 26,885,597
ATM Program |  |  |
Stockholders Equity [Line Items] |  |  |
Net proceeds |  | $ 473 | $ 776
Limited Partners Common Units |  |  |
Stockholders Equity [Line Items] |  |  |
Units issued | 0 | 13,846,998 | 26,347,887

X
- Definition Common Stock, Monetary Value of Shares Authorized + References No definition available. + Details
Name: | mpc_CommonStockMonetaryValueofSharesAuthorized
Namespace Prefix: | mpc_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Stockholders Equity [Line Items] + References No definition available. + Details
Name: | mpc_StockholdersEquityLineItems
Namespace Prefix: | mpc_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Monetary value of the issuance of new units of limited partnership interest in a public offering, net of offering costs. This is a parenthetical disclosure. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 5 -Subparagraph (SAB Topic 4.F) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187171-122770 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 + Details
Name: | us-gaap_PartnersCapitalAccountPublicSaleOfUnitsNetOfOfferingCosts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Total units issued during the year due to the sale of units. All partners include general, limited and preferred partners. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 272 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 + Details
Name: | us-gaap_PartnersCapitalAccountUnitsSaleOfUnits
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=mpc_ATMProgramMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PartnerTypeOfPartnersCapitalAccountAxis=mpc_LimitedPartnersCommonUnitsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |