Acquisitions (Acquisition of Ozark Pipeline) (Details) - Ozark Pipeline bbl / d in Thousands, $ in Millions	Mar. 01, 2017 USD ($) bbl / d in mi
Business Acquisition [Line Items]
Pipeline length \| mi	433
Pipeline diameter \| in	22
Crude oil throughput \| bbl / d	230
MPLX
Business Acquisition [Line Items]
Cash payment for acquisition \| $	$ 219

The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)(1)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109223946&loc=d3e3213-108585

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration