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Equity - GP/IDR Exchange (Details) - USD ($) $ in Millions |  | 3 Months Ended
--- | --- | ---
Feb. 01, 2018 | Mar. 31, 2018
Stockholders Equity Note [Line Items] |  |  |
Conversion of GP economic interests |  |  | 264,413,309
Partners' Capital Account, Exchanges and Conversions |  |  | $ 0
Limited Partners Common Units |  |  |
Stockholders Equity Note [Line Items] |  |  |
Conversion of GP economic interests | 275,000,000 | [1] | 275,000,000
Partners' Capital Account, Exchanges and Conversions | $ 10,400 |  |
[1] | MPC agreed to waive approximately one-third of the first quarter 2018 distributions on the common units issued in connection with this transaction. As a result of this waiver, MPC will not receive $23.7 million of the distributions that would have otherwise accrued on such common units with respect to the first quarter 2018. See Note 4 for information regarding this acquisition.

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