Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Segment Reporting Information [Line Items]
Sales to external customers	$ 232.4	$ 41.8
Sales to affiliates	491.9	485.1
Purchased gas, NGLs and crude oil	(538.9)	(395.4)
Operating expenses	(46.2)	(41.0)
Loss on derivatives activity	(1.3)	0
Segment profit	137.9	90.5
Depreciation and Amortization	(48.2)	(44.4)
Goodwill	3,821.6	401.7	401.7
Capital Expenditures	67.9	83.2
Identifiable assets	9,353.8		2,309.8
Texas
Segment Reporting Information [Line Items]
Sales to external customers	48.3	30.5
Sales to affiliates	335.9	325.6
Purchased gas, NGLs and crude oil	(257.7)	(257.4)
Operating expenses	(31.7)	(33.8)
Loss on derivatives activity	0
Segment profit	94.8	64.9
Depreciation and Amortization	(27.2)	(26.7)
Goodwill	1,256.7	325.4
Capital Expenditures	25.1	50.8
Identifiable assets	3,171.0		1,460.0
Louisiana
Segment Reporting Information [Line Items]
Sales to external customers	153.2	0
Sales to affiliates	0.5	0
Purchased gas, NGLs and crude oil	(140.5)	0
Operating expenses	(5.1)	0
Loss on derivatives activity	0
Segment profit	8.1	0
Depreciation and Amortization	(5.2)	0
Goodwill	885.1	0
Capital Expenditures	22.1	0
Identifiable assets	2,715.3		0
Oklahoma
Segment Reporting Information [Line Items]
Sales to external customers	11.5	11.3
Sales to affiliates	162.9	159.5
Purchased gas, NGLs and crude oil	(133.8)	(138.0)
Operating expenses	(6.7)	(7.2)
Loss on derivatives activity	0
Segment profit	33.9	25.6
Depreciation and Amortization	(14.2)	(17.7)
Goodwill	190.3	76.3
Capital Expenditures	10.2	32.4
Identifiable assets	896.4		777.1
Ohio River Valley
Segment Reporting Information [Line Items]
Sales to external customers	19.4	0
Sales to affiliates	0	0
Purchased gas, NGLs and crude oil	(14.3)	0
Operating expenses	(2.7)	0
Loss on derivatives activity	0
Segment profit	2.4	0
Depreciation and Amortization	(1.5)	0
Goodwill	106.0	0
Capital Expenditures	5.0	0
Identifiable assets	634.8		0
Corporate
Segment Reporting Information [Line Items]
Sales to external customers	0	0
Sales to affiliates	(7.4)	0
Purchased gas, NGLs and crude oil	7.4	0
Operating expenses	0	0
Loss on derivatives activity	(1.3)
Segment profit	(1.3)	0
Depreciation and Amortization	(0.1)	0
Goodwill	1,383.5	0
Capital Expenditures	5.5	0
Identifiable assets	$ 1,936.3		$ 72.7