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Consolidated Balance Sheets (Parenthetical) - shares shares in Millions	Dec. 31, 2018	Dec. 31, 2017
Limited Partners Common Units | Public
Units issued	289	289
Units outstanding	289	289
Limited Partners Common Units | MPC
Units issued	505	118
Units outstanding	505	118
Limited Partners Class B Units
Units issued	0	0
Units outstanding	0	0
Common Unitholder GP | MPC
Units issued	0	0
Units outstanding	0
General Partner | MPC
Units issued	0	8
Units outstanding	0	8

X

- Definition

The number of general partner units issued.

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