XML 66 R52.htm IDEA: XBRL DOCUMENT
v3.7.0.1

MPLX LP (Detail) - MPLX LP | Dec. 04, 2015 | Mar. 31, 2017
--- | --- | ---
Noncontrolling Interest [Line Items] |  |
Ownership percentage of general partner interest |  | 100.00%
Public's ownership interest in MPLX (in percentage) |  | 72.20%
MarkWest |  |
Noncontrolling Interest [Line Items] |  |
Common units conversion ratio | 1.09 |
General Partner and Limited Partner |  |
Noncontrolling Interest [Line Items] |  |
MPC's partnership interest in MPLX (in percentage) |  | 27.80%
General Partner |  |
Noncontrolling Interest [Line Items] |  |
MPC's partnership interest in MPLX (in percentage) |  | 2.00%

X
- Definition Ratio applied to the conversion of Markwest shares to MPLX common units. + References No definition available. + Details
Name: | mpc_CommonUnitsConversionRatio
Namespace Prefix: | mpc_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage ownership of the general partner interest + References No definition available. + Details
Name: | mpc_OwnershipPercentageOfGeneralPartnerInterest
Namespace Prefix: | mpc_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- 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
Name: | us-gaap_MinorityInterestLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity. + References No definition available. + Details
Name: | us-gaap_MinorityInterestOwnershipPercentageByNoncontrollingOwners
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition The parent entity's interest in net assets of the subsidiary, expressed as a percentage. + References No definition available. + Details
Name: | us-gaap_MinorityInterestOwnershipPercentageByParent
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | dei_LegalEntityAxis=mpc_MplxLpMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_BusinessAcquisitionAxis=mpc_MarkWestMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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