Segment Information (Details) - USD ($) $ in Millions	3 Months Ended			12 Months Ended
	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting
Product sales				$ 3,008.9	$ 3,253.7	$ 2,159.3
Product sales - related parties				134.3	119.4	505.6
Midstream services				467.2	451.0	253.4
Midstream services - related parties				653.1	618.6	567.4
Cost of sales				(3,015.5)	(3,245.3)	(2,494.5)
Operating expenses				(398.5)	(419.9)	(283.6)
Gain on litigation settlement						6.1
(Gain) loss on derivatives recognized in net income (loss)				(11.1)	9.4	22.1
Segment profit (loss)				838.4	786.9	735.8
Depreciation and amortization				(503.9)	(387.3)	(284.3)
Impairments	$ (873.3)	$ (764.2)	$ (799.2)	(873.3)	(1,563.4)
Goodwill		2,413.9		1,542.2	2,413.9	3,684.7
Capital expenditures				676.1	570.5	758.7
Segment identifiable assets		9,541.3		10,275.9	9,541.3
Corporate, Non-Segment
Segment Reporting
Product sales - related parties				(333.0)	(66.2)	(64.3)
Midstream services - related parties				(86.8)	(16.8)	(5.8)
Cost of sales				419.8	83.0	70.1
(Gain) loss on derivatives recognized in net income (loss)				(11.1)	9.4	22.1
Segment profit (loss)				(11.1)	9.4	22.1
Depreciation and amortization				(9.2)	(7.2)	(2.7)
Impairments				(307.0)
Goodwill		1,426.9		1,119.9	1,426.9	1,426.9
Capital expenditures				9.1	15.1	13.9
Segment identifiable assets		1,751.1		1,422.7	1,751.1
Texas Operating Segment | Operating Segments
Segment Reporting
Product sales				237.2	320.0	216.5
Product sales - related parties				287.6	123.3	348.8
Midstream services				104.2	100.2	56.3
Midstream services - related parties				439.3	456.7	410.8
Cost of sales				(483.4)	(412.2)	(456.9)
Operating expenses				(168.5)	(181.8)	(146.8)
Segment profit (loss)				416.4	406.2	428.7
Depreciation and amortization				(196.9)	(169.7)	(125.8)
Impairments				(473.1)	(496.3)
Goodwill		703.5		232.0	703.5	1,168.2
Capital expenditures				217.9	268.0	271.0
Segment identifiable assets		3,709.5		3,142.6	3,709.5
Louisiana Operating Segment | Operating Segments
Segment Reporting
Product sales				1,632.5	1,527.7	1,612.7
Product sales - related parties				57.8	48.5	65.7
Midstream services				215.4	244.1	153.2
Midstream services - related parties				95.8	20.0	5.8
Cost of sales				(1,729.0)	(1,567.6)	(1,674.2)
Operating expenses				(96.6)	(105.9)	(64.9)
Gain on litigation settlement						6.1
Segment profit (loss)				175.9	166.8	104.4
Depreciation and amortization				(114.8)	(109.1)	(69.4)
Impairments					(787.3)
Goodwill						786.8
Capital expenditures				79.1	59.2	273.1
Segment identifiable assets		2,309.3		2,349.3	2,309.3
Oklahoma Operating Segment | Operating Segments
Segment Reporting
Product sales				48.5	5.0	13.1
Product sales - related parties				120.4	13.0	154.9
Midstream services				82.2	28.3	1.7
Midstream services - related parties				185.9	140.7	149.1
Cost of sales				(184.9)	(17.9)	(142.6)
Operating expenses				(52.1)	(30.3)	(28.7)
Segment profit (loss)				200.0	138.8	147.5
Depreciation and amortization				(140.6)	(49.8)	(49.4)
Impairments					(0.6)
Goodwill		190.3		190.3	190.3	190.3
Capital expenditures				295.7	40.7	17.1
Segment identifiable assets		873.4		2,524.5	873.4
Crude And Condensate Segment | Operating Segments
Segment Reporting
Product sales				1,090.7	1,401.0	317.0
Product sales - related parties				1.5	0.8	0.5
Midstream services				65.4	78.4	42.2
Midstream services - related parties				18.9	18.0	7.5
Cost of sales				(1,038.0)	(1,330.6)	(290.9)
Operating expenses				(81.3)	(101.9)	(43.2)
Segment profit (loss)				57.2	65.7	33.1
Depreciation and amortization				(42.4)	(51.5)	(37.0)
Impairments				(93.2)	(279.2)
Goodwill		93.2			93.2	112.5
Capital expenditures				74.3	187.5	$ 183.6
Segment identifiable assets		$ 898.0		$ 836.8	$ 898.0