MPLX LP - Noncontrolling Interest (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2017	Mar. 31, 2016
Impact from equity transactions of MPLX, net of tax	$ 114	$ 250
Additional Paid-in Capital
Increase (decrease) in MPC's additional paid in capital for the issuance of MPLX LP common units to the public	10	(40)
Increase in MPC's additional paid in capital for the issuance of MPLX LP common units and general partner units to MPC	96	0
Net transfers (to) from noncontrolling interests	106	(40)
Tax impact	(34)	(65)
Impact from equity transactions of MPLX, net of tax	$ 72	$ (105)

Represents a sale (new stock issuance) by a subsidiary to noncontrolling interests (third parties, parties directly or indirectly unrelated to parent) during the period. The capital transaction by subsidiary does not result in a loss of control by the parent, but does effect a change in total (consolidated) equity attributable to the parent.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section S99
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=64809438&loc=SL4573702-111684

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 55
-Paragraph 4M
-URI http://asc.fasb.org/extlink&oid=65897068&loc=SL4591554-111686

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