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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

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- Definition

Percentage ownership of the general partner interest

+ References

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+ Details

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- 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.

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- Definition

The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

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- Definition

The parent entity's interest in net assets of the subsidiary, expressed as a percentage.

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- Details

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