Segment Information - Financial Information and Assets (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016	Dec. 31, 2016
Segment Reporting
Product sales		$ 990.0	$ 588.5
Product sales—related parties		42.7	24.5
Midstream services		127.4	114.5
Midstream services—related parties		159.0	162.6
Cost of sales	[1]	(1,002.3)	(586.2)
Operating expenses	[2]	(104.1)	(98.2)
Gain (loss) on derivative activity		2.8	(0.4)
Segment profit		215.5	205.3
Depreciation and amortization		(128.3)	(121.9)
Impairments		(7.0)	(873.3)
Goodwill		1,542.2	1,540.6	$ 1,542.2
Capital expenditures		248.1	120.4
Total identifiable assets		10,177.5		10,275.9
Corporate
Segment Reporting
Product sales		0.0	0.0
Product sales—related parties		(139.2)	(31.0)
Midstream services		0.0	0.0
Midstream services—related parties		(27.8)	(10.6)
Cost of sales		167.0	41.6
Operating expenses		0.0	0.0
Gain (loss) on derivative activity		2.8	(0.4)
Segment profit		2.8	(0.4)
Depreciation and amortization		(2.4)	(2.2)
Impairments			(307.0)
Goodwill		1,119.9	1,119.9
Capital expenditures		9.0	1.9
Total identifiable assets		1,240.5		1,422.7
Texas | Operating Segments
Segment Reporting
Product sales		85.1	62.5
Product sales—related parties		106.5	37.3
Midstream services		27.8	27.4
Midstream services—related parties		105.1	110.3
Cost of sales		(179.2)	(91.3)
Operating expenses		(43.9)	(39.3)
Gain (loss) on derivative activity		0.0	0.0
Segment profit		101.4	106.9
Depreciation and amortization		(49.8)	(46.2)
Impairments			(473.1)
Goodwill		232.0	230.4
Capital expenditures		28.3	23.3
Total identifiable assets		3,132.6		3,142.6
Louisiana | Operating Segments
Segment Reporting
Product sales		544.5	287.7
Product sales—related parties		10.2	7.4
Midstream services		53.1	55.2
Midstream services—related parties		29.0	12.7
Cost of sales		(564.7)	(302.1)
Operating expenses		(25.4)	(23.3)
Gain (loss) on derivative activity		0.0	0.0
Segment profit		46.7	37.6
Depreciation and amortization		(28.1)	(29.3)
Impairments			0.0
Goodwill		0.0	0.0
Capital expenditures		32.7	22.7
Total identifiable assets		2,312.7		2,349.3
Oklahoma | Operating Segments
Segment Reporting
Product sales		14.5	7.8
Product sales—related parties		64.4	10.6
Midstream services		27.9	15.1
Midstream services—related parties		49.4	45.0
Cost of sales		(88.7)	(19.3)
Operating expenses		(14.1)	(12.8)
Gain (loss) on derivative activity		0.0	0.0
Segment profit		53.4	46.4
Depreciation and amortization		(36.5)	(33.8)
Impairments			0.0
Goodwill		190.3	190.3
Capital expenditures		140.7	69.2
Total identifiable assets		2,629.8		2,524.5
Crude and Condensate | Operating Segments
Segment Reporting
Product sales		345.9	230.5
Product sales—related parties		0.8	0.2
Midstream services		18.6	16.8
Midstream services—related parties		3.3	5.2
Cost of sales		(336.7)	(215.1)
Operating expenses		(20.7)	(22.8)
Gain (loss) on derivative activity		0.0	0.0
Segment profit		11.2	14.8
Depreciation and amortization		(11.5)	(10.4)
Impairments			(93.2)
Goodwill		0.0	0.0
Capital expenditures		37.4	$ 3.3
Total identifiable assets		$ 861.9		$ 836.8

[1] Includes related party cost of sales of $28.7 million and $42.6 million for the three months ended March 31, 2017 and 2016, respectively.

[2] Includes related party operating expenses of $0.2 million and $0.1 million for the three months ended March 31, 2017 and 2016, respectively.