Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Mar. 07, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Sales to external customers	$ 755.0	$ 47.5	$ 987.5	$ 89.3
Sales to affiliates	173.8	540.5	665.7	1,025.6
Purchased gas, NGLs and crude oil	(661.9)	(448.7)	(1,200.8)	(844.1)
Operating expenses	(72.6)	(39.2)	(118.7)	(80.2)
Loss on derivatives activity	(1.6)	0	(2.9)	0
Segment profit	192.7	100.1	330.8	190.6
Depreciation and Amortization	(74.2)	(46.2)	(122.4)	(90.6)
Goodwill	3,693.5	401.7	3,693.5	401.7	3,291.6	401.7
Capital Expenditures	215.6	52.3	283.6	135.5
Identifiable assets	9,379.2		9,379.2			2,309.8
Texas
Segment Reporting Information [Line Items]
Sales to external customers	88.6	33.2	136.9	63.7
Sales to affiliates	152.9	367.3	488.8	692.9
Purchased gas, NGLs and crude oil	(88.5)	(295.1)	(346.2)	(552.5)
Operating expenses	(38.6)	(31.4)	(70.3)	(65.2)
Loss on derivatives activity	0		0
Segment profit	114.4	74.0	209.2	138.9
Depreciation and Amortization	(32.8)	(26.7)	(60.1)	(53.4)
Goodwill	1,168.1	325.4	1,168.1	325.4
Capital Expenditures	75.4	36.0	100.5	86.8
Identifiable assets	3,176.4		3,176.4			1,460.0
Louisiana
Segment Reporting Information [Line Items]
Sales to external customers	577.4	0	730.6	0
Sales to affiliates	1.7	0	2.2	0
Purchased gas, NGLs and crude oil	(530.8)	0	(671.3)	0
Operating expenses	(16.6)	0	(21.8)	0
Loss on derivatives activity	0		0
Segment profit	31.7	0	39.7	0
Depreciation and Amortization	(19.1)	0	(24.3)	0
Goodwill	786.7	0	786.7	0
Capital Expenditures	121.2	0	143.3	0
Identifiable assets	2,891.9		2,891.9			0
Oklahoma
Segment Reporting Information [Line Items]
Sales to external customers	0	14.3	11.5	25.6
Sales to affiliates	47.2	173.2	210.1	332.7
Purchased gas, NGLs and crude oil	0	(153.6)	(133.8)	(291.6)
Operating expenses	(7.3)	(7.8)	(14.0)	(15.0)
Loss on derivatives activity	0		0
Segment profit	39.9	26.1	73.8	51.7
Depreciation and Amortization	(11.6)	(19.5)	(25.8)	(37.2)
Goodwill	190.3	76.3	190.3	76.3
Capital Expenditures	(2.2)	16.3	8.0	48.7
Identifiable assets	907.9		907.9			777.1
Ohio River Valley
Segment Reporting Information [Line Items]
Sales to external customers	89.0	0	108.5	0
Sales to affiliates	0	0	0	0
Purchased gas, NGLs and crude oil	(70.6)	0	(84.9)	0
Operating expenses	(10.1)	0	(12.6)	0
Loss on derivatives activity	0		0
Segment profit	8.3	0	11.0	0
Depreciation and Amortization	(9.9)	0	(11.3)	0
Goodwill	118.0	0	118.0	0
Capital Expenditures	18.0	0	23.1	0
Identifiable assets	614.1		614.1			0
Corporate
Segment Reporting Information [Line Items]
Sales to external customers	0	0	0	0
Sales to affiliates	(28.0)	0	(35.4)	0
Purchased gas, NGLs and crude oil	28.0	0	35.4	0
Operating expenses	0	0	0	0
Loss on derivatives activity	(1.6)		(2.9)
Segment profit	(1.6)	0	(2.9)	0
Depreciation and Amortization	(0.8)	0	(0.9)	0
Goodwill	1,430.4	0	1,430.4	0
Capital Expenditures	3.2	0	8.7	0
Identifiable assets	$ 1,788.9		$ 1,788.9			$ 72.7