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Acquisitions Acquisition of HST, WHC & MPLXT (Details) bbl in Millions, $ in Millions |  |  | 6 Months Ended
--- | --- | --- | ---
Mar. 01, 2017 USD ($) mi shares bbl | Mar. 31, 2016 USD ($) | Jun. 30, 2017 USD ($) shares
Business Acquisition [Line Items] |  |  |  |
Contribution from MPC | $ |  |  |  | $ 12
Number of natural gas liquids storage caverns |  | 9 |  |
Number of light product terminals |  | 62 |  |
HST & WHC & MPLXT [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned | $ |  | $ 504 |  |
Business Acquisition, Equity Interest Issued or Issuable, Fair Value Assigned | $ |  | 503 |  |
Partners' Capital Account, Units, Acquisitions | shares | [1] |  |  | 13,224,873
HST & WHC & MPLXT [Member] | Cash and Cash Equivalents [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Payments to Acquire Businesses, Gross | $ |  | $ 1,500 |  |
HST & WHC & MPLXT [Member] | General Partner Units [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Partners' Capital Account, Units, Acquisitions | shares | [1] | 264,497 |  | 264,497
HST & WHC & MPLXT [Member] | Limited Partners Common Units [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Partners' Capital Account, Units, Acquisitions | shares | [1] |  |  | 12,960,376
HST & WHC & MPLXT [Member] | General Partner Common Units [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Partners' Capital Account, Units, Acquisitions | shares | [1] | 9,197,900 |  |
MPLX Logistics LLC [Member] | HST & WHC & MPLXT [Member] | Limited Partners Common Units [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Partners' Capital Account, Units, Acquisitions | shares | [1] | 2,630,427 |  |
MPLX Holdings Inc [Member] | HST & WHC & MPLXT [Member] | Limited Partners Common Units [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Partners' Capital Account, Units, Acquisitions | shares | [1] | 1,132,049 |  |
Natural gas liquids storage caverns [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Storage Capacity | bbl |  | 1.8 |  |
Light-product terminal [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Storage Capacity | bbl |  | 23.6 |  |
Refined Products [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Miles of pipeline | mi |  | 430 |  |
Crude Oil [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Miles of pipeline | mi |  | 174 |  |
Wholly Owned Properties [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Number of light product terminals |  | 59 |  |
Property Subject to Operating Lease [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Number of light product terminals |  | 1 |  |
Partially Owned Properties [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Number of light product terminals |  | 2 |  |
MPC |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Contribution from MPC | $ |  | $ 6 | $ 15 |
MPC | Limited Partners Common Units [Member] |  |  |  |
Business Acquisition [Line Items] |  |  |  |
Contribution from MPC | $ |  |  |  | $ 0
[1] | See Note 3 for information regarding the HST, WHC and MPLXT acquisition.

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