Segment Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Mar. 07, 2014	Dec. 31, 2013
Segment Reporting Information [Line Items]
Sales to external customers	$ 647.7	$ 46.8	$ 1,635.2	$ 136.1
Sales to affiliates	206.3	531.4	872.0	1,557.0
Purchased gas, NGLs and crude oil	(597.2)	(435.5)	(1,798.0)	(1,279.6)
Operating expenses	(76.7)	(35.8)	(195.5)	(116.0)
Gain on Litigation Settlement	6.1	0	6.1	0
Gain (loss) on derivative activity	1.0	0	(1.9)	0
Segment profit	187.2	106.9	517.9	297.5
Depreciation and Amortization	(73.4)	(48.0)	(195.8)	(138.6)
Goodwill	3,694.6	401.7	3,694.6	401.7	3,291.9	401.7
Capital Expenditures	207.4	37.1	493.5	172.6
Identifiable assets	9,527.8		9,527.8			2,309.8
Texas
Segment Reporting Information [Line Items]
Sales to external customers	77.3	32.9	214.3	96.6
Sales to affiliates	148.9	359.4	637.7	1,052.3
Purchased gas, NGLs and crude oil	(76.8)	(286.2)	(423.0)	(838.7)
Operating expenses	(36.2)	(26.9)	(106.5)	(92.0)
Gain on Litigation Settlement	0		0
Gain (loss) on derivative activity	0		0
Segment profit	113.2	79.2	322.5	218.2
Depreciation and Amortization	(31.6)	(29.0)	(91.7)	(82.4)
Goodwill	1,168.2	325.4	1,168.2	325.4
Capital Expenditures	79.7	27.1	180.2	113.9
Identifiable assets	3,236.9		3,236.9			1,460.0
Louisiana
Segment Reporting Information [Line Items]
Sales to external customers	491.3	0	1,221.9	0
Sales to affiliates	39.5	0	41.7	0
Purchased gas, NGLs and crude oil	(486.9)	0	(1,158.2)	0
Operating expenses	(23.7)	0	(45.5)	0
Gain on Litigation Settlement	6.1		6.1
Gain (loss) on derivative activity	0		0
Segment profit	26.3	0	66.0	0
Depreciation and Amortization	(19.1)	0	(43.4)	0
Goodwill	786.8	0	786.8	0
Capital Expenditures	79.1	0	222.4	0
Identifiable assets	2,925.3		2,925.3			0
Oklahoma
Segment Reporting Information [Line Items]
Sales to external customers	0	13.9	11.5	39.5
Sales to affiliates	45.9	172.0	256.0	504.7
Purchased gas, NGLs and crude oil	0	(149.3)	(133.8)	(440.9)
Operating expenses	(7.0)	(8.9)	(20.9)	(24.0)
Gain on Litigation Settlement	0		0
Gain (loss) on derivative activity	0		0
Segment profit	38.9	27.7	112.8	79.3
Depreciation and Amortization	(11.8)	(19.0)	(37.6)	(56.2)
Goodwill	190.3	76.3	190.3	76.3
Capital Expenditures	2.5	10.0	10.5	58.7
Identifiable assets	894.5		894.5			777.1
Ohio River Valley
Segment Reporting Information [Line Items]
Sales to external customers	79.1	0	187.5	0
Sales to affiliates	0	0	0	0
Purchased gas, NGLs and crude oil	(61.5)	0	(146.4)	0
Operating expenses	(9.8)	0	(22.6)	0
Gain on Litigation Settlement	0		0
Gain (loss) on derivative activity	0		0
Segment profit	7.8	0	18.5	0
Depreciation and Amortization	(10.0)	0	(21.6)	0
Goodwill	112.5	0	112.5	0
Capital Expenditures	42.2	0	67.8	0
Identifiable assets	677.0		677.0			0
Corporate
Segment Reporting Information [Line Items]
Sales to external customers	0	0	0	0
Sales to affiliates	(28.0)	0	(63.4)	0
Purchased gas, NGLs and crude oil	28.0	0	63.4	0
Operating expenses	0	0	0	0
Gain on Litigation Settlement	0		0
Gain (loss) on derivative activity	1.0		(1.9)
Segment profit	1.0	0	(1.9)	0
Depreciation and Amortization	(0.9)	0	(1.5)	0
Goodwill	1,436.8	0	1,436.8	0
Capital Expenditures	3.9	0	12.6	0
Identifiable assets	$ 1,794.1		$ 1,794.1			$ 72.7