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MPLX LP - Reorganization Transactions (Details) - MPLX LP - USD ($) shares in Millions, $ in Millions | Mar. 01, 2017 | Sep. 01, 2016 | Mar. 31, 2016
--- | --- | --- | ---
General partners' contributed capital |  | $ 225 |
Limited Partner |  |  |
Units issued, number of units | 13 | 7 | 23
General Partner and Limited Partner |  |  |
Increase in ownership percentage by MPC |  | 1.00% |

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