(Deficit) Equity - Distributions to Noncontrolling Interest (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Zydeco Pipeline Company LLC (“Zydeco”)
Class of Stock [Line Items]
Distributions to noncontrolling interest	$ 8.9	$ 20.3	$ 67.1
Odyssey Pipeline L.L.C.
Class of Stock [Line Items]
Distributions to noncontrolling interest	$ 10.0	$ 9.9	$ 6.1

Amount of cash outflow in the form of ordinary dividends provided by the non-wholly owned subsidiary to noncontrolling interests.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

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