Significant Accounting Policies Significant Accounting Policies (Goodwill) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Mar. 07, 2014	Dec. 31, 2013	Dec. 31, 2012
Goodwill [Line Items]
Goodwill	$ 3,684,700,000	$ 3,283,100,000	$ 401,700,000	$ 401,700,000
Texas Operating Segment
Goodwill [Line Items]
Goodwill	1,168,200,000		325,400,000	325,400,000
Louisiana Operating Segment
Goodwill [Line Items]
Goodwill	786,800,000		0	0
Oklahoma Operating Segment
Goodwill [Line Items]
Goodwill	190,300,000		76,300,000	76,300,000
ORV Operating Segments
Goodwill [Line Items]
Goodwill	112,500,000		0	0
Corporate Segment
Goodwill [Line Items]
Goodwill	1,426,900,000		0	0
EnLink Midstream Holdings, LP
Goodwill [Line Items]
Increase in the Partnership's goodwill	$ 3,300,000,000