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Consolidated Balance Sheets (Parenthetical) - shares shares in Millions	Jun. 30, 2017	Dec. 31, 2016
Limited Partners Common Units [Member] | Public
Units issued	284	271
Units outstanding	284	271
Limited Partners Class B Units
Units issued	4	4
Units outstanding	4	4
MPC | Limited Partners Common Units [Member]
Units issued	90	86
Units outstanding	90	86
MPC | GP Held Limited Partners Common Units
Units issued	9	0
Units outstanding	9	0
MPC | General Partner
GP units issued	8	7
GP units outstanding	8	7

X

- Definition

The number of general partner units issued.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 5
-Subparagraph (SAB Topic 4.F)
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+ References

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-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187171-122770

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