Segment Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Segment Reporting Information [Line Items]
Product sales	$ 738.3	$ 956.2	$ 1,326.8	$ 1,626.9
Product sales - affiliates	31.7	31.7	56.2	47.9
Midstream services	108.3	135.9	222.8	238.3
Midstream services - affiliates	160.6	149.5	323.2	300.5
Cost of sales	(732.4)	(968.2)	(1,318.6)	(1,625.6)
Operating expenses	(100.1)	(109.1)	(198.3)	(207.6)
Loss on derivative activity	(5.7)	1.2	(6.1)	1.4
Segment profit	200.7	197.2	406.0	381.8
Depreciation and amortization	(124.9)	(97.7)	(246.8)	(189.0)
Impairments	0.0	0.0	(873.3)	0.0
Goodwill	1,541.3	3,731.2	1,541.3	3,731.2	$ 2,413.9
Capital expenditures	140.2	164.8	260.6	340.5
Segment identifiable assets	10,162.3		10,162.3		9,541.3
Texas Operating Segment
Segment Reporting Information [Line Items]
Product sales	41.9	81.2	104.4	131.0
Product sales - affiliates	72.7	35.0	110.0	60.9
Midstream services	23.2	36.0	50.6	55.6
Midstream services - affiliates	111.9	115.8	222.2	231.3
Cost of sales	(103.6)	(118.4)	(194.9)	(185.6)
Operating expenses	(43.0)	(45.5)	(82.3)	(92.6)
Loss on derivative activity	0.0	0.0	0.0	0.0
Segment profit	103.1	104.1	210.0	200.6
Depreciation and amortization	(48.7)	(42.8)	(94.9)	(79.2)
Impairments			(473.1)
Goodwill	231.1	1,185.0	231.1	1,185.0	703.5
Capital expenditures	57.2	80.9	80.5	154.4
Segment identifiable assets	3,179.9		3,179.9		3,709.5
Louisiana Operating Segment
Segment Reporting Information [Line Items]
Product sales	399.5	401.2	687.2	773.4
Product sales - affiliates	15.2	17.0	22.6	24.1
Midstream services	52.7	63.2	107.9	121.1
Midstream services - affiliates	25.5	0.3	38.2	0.4
Cost of sales	(425.5)	(418.2)	(727.6)	(789.1)
Operating expenses	(25.4)	(27.2)	(48.7)	(51.5)
Loss on derivative activity	0.0	0.0	0.0	0.0
Segment profit	42.0	36.3	79.6	78.4
Depreciation and amortization	(28.6)	(26.9)	(57.9)	(54.4)
Impairments			0.0
Goodwill	0.0	786.8	0.0	786.8	0.0
Capital expenditures	14.1	14.7	36.8	29.9
Segment identifiable assets	2,330.9		2,330.9		2,309.3
Oklahoma Operating Segment
Segment Reporting Information [Line Items]
Product sales	8.9	0.1	16.7	0.1
Product sales - affiliates	22.5	1.7	33.1	5.4
Midstream services	18.0	9.8	33.1	20.5
Midstream services - affiliates	41.7	29.1	86.7	60.3
Cost of sales	(31.6)	(2.0)	(50.9)	(7.1)
Operating expenses	(11.8)	(9.1)	(24.6)	(16.1)
Loss on derivative activity	0.0	0.0	0.0	0.0
Segment profit	47.7	29.6	94.1	63.1
Depreciation and amortization	(34.8)	(11.8)	(68.6)	(25.3)
Impairments			0.0
Goodwill	190.3	190.3	190.3	190.3	190.3
Capital expenditures	63.1	12.3	132.3	17.5
Segment identifiable assets	2,413.6		2,413.6		873.4
Crude And Condensate Segment
Segment Reporting Information [Line Items]
Product sales	288.0	473.7	518.5	722.4
Product sales - affiliates	0.9	14.0	1.1	14.0
Midstream services	14.4	26.9	31.2	41.1
Midstream services - affiliates	4.0	4.3	9.2	8.5
Cost of sales	(273.8)	(465.6)	(488.9)	(700.3)
Operating expenses	(19.9)	(27.3)	(42.7)	(47.4)
Loss on derivative activity	0.0	0.0	0.0	0.0
Segment profit	13.6	26.0	28.4	38.3
Depreciation and amortization	(10.6)	(14.5)	(21.0)	(26.9)
Impairments			(93.2)
Goodwill	0.0	142.1	0.0	142.1	93.2
Capital expenditures	0.9	54.4	4.2	132.0
Segment identifiable assets	780.6		780.6		898.0
Corporate Segment
Segment Reporting Information [Line Items]
Product sales	0.0	0.0	0.0	0.0
Product sales - affiliates	(79.6)	(36.0)	(110.6)	(56.5)
Midstream services	0.0	0.0	0.0	0.0
Midstream services - affiliates	(22.5)	0.0	(33.1)	0.0
Cost of sales	102.1	36.0	143.7	56.5
Operating expenses	0.0	0.0	0.0	0.0
Loss on derivative activity	(5.7)	1.2	(6.1)	1.4
Segment profit	(5.7)	1.2	(6.1)	1.4
Depreciation and amortization	(2.2)	(1.7)	(4.4)	(3.2)
Impairments			(307.0)
Goodwill	1,119.9	1,427.0	1,119.9	1,427.0	1,426.9
Capital expenditures	4.9	$ 2.5	6.8	$ 6.7
Segment identifiable assets	$ 1,457.3		$ 1,457.3		$ 1,751.1