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MPLX LP - ATM Program (Details) - USD ($) shares in Millions, $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2017 | Mar. 31, 2016
Noncontrolling Interest [Line Items] |  |
Net proceeds from issuance of MPLX LP common limited partners units | $ 148 | $ 315
MPLX LP | ATM Program |  |
Noncontrolling Interest [Line Items] |  |
Net proceeds from issuance of MPLX LP common limited partners units | 148 |
Remaining authorized issuance amount | $ 570 |
MPLX LP | ATM Program | Limited Partners Common Units |  |
Noncontrolling Interest [Line Items] |  |
Sale of units (in number of common units) | 4 |

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