Consolidated Statements of Operations - USD ($) shares in Thousands, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenues:
Revenues	$ 3,654.1	$ 3,880.9	$ 2,520.5
Related party (Note 16)	1.0	1.8	2.6
Costs of product/services sold (exclusive of items shown separately below):
Product costs - related party (Note 16)	134.7	15.3	17.7
Total costs of products/services sold	3,129.4	3,374.7	1,925.1
Operating expenses and other:
Operations and maintenance	125.8	136.0	158.1
General and administrative	88.1	96.5	88.2
Depreciation, amortization and accretion	168.7	191.7	229.6
Loss on long-lived assets, net	28.6	65.6	65.6
Goodwill impairment	0.0	38.8	162.6
Loss on contingent consideration	0.0	57.0	0.0
Total expenses	411.2	585.6	704.1
Operating income (loss)	113.5	(79.4)	(108.7)
Earnings from unconsolidated affiliates, net	53.3	47.8	31.5
Interest and debt expense, net	(99.2)	(99.4)	(125.1)
Gain (loss) on modification/extinguishment of debt	(0.9)	(37.7)	10.0
Other income, net	0.4	1.3	0.5
Income (loss) before income taxes	67.1	(167.4)	(191.8)
(Provision) benefit for income taxes	(0.1)	0.8	(0.3)
Net income (loss)	67.0	(166.6)	(192.1)
Net income attributable to non-controlling partner	(16.2)	(25.3)	(24.2)
Net income (loss) attributable to parent	50.8	(191.9)	(216.3)
Net income attributable to preferred units	60.1	62.5	28.7
Net loss attributable to partners	(9.3)	(254.4)	(245.0)
Common unitholders’ interest in net loss	$ (9.3)	$ (254.4)	$ (245.0)
Net loss per limited partner unit:
Basic (dollars per unit)	$ (0.13)	$ (3.64)	$ (3.55)
Diluted (dollars per unit)	$ (0.13)	$ (3.64)	$ (3.55)
Weighted-average limited partners’ units outstanding (in thousands):
Basic (units)	71,205	69,839	69,017
Dilutive units (units)	0	0	0
Diluted (units)	71,205	69,839	69,017
CMLP
Revenues:
Revenues	$ 3,654.1	$ 3,880.9	$ 2,520.5
Related party (Note 16)	1.0	1.8	2.6
Costs of product/services sold (exclusive of items shown separately below):
Product costs - related party (Note 16)	134.7	15.3	17.7
Total costs of products/services sold	3,129.4	3,374.7	1,925.1
Operating expenses and other:
Operations and maintenance	125.8	136.0	155.0
General and administrative	83.5	93.1	85.6
Depreciation, amortization and accretion	181.4	202.7	240.5
Loss on long-lived assets, net	28.6	65.6	65.6
Goodwill impairment	0.0	38.8	162.6
Loss on contingent consideration	0.0	57.0	0.0
Total expenses	419.3	593.2	709.3
Operating income (loss)	105.4	(87.0)	(113.9)
Earnings from unconsolidated affiliates, net	53.3	47.8	31.5
Interest and debt expense, net	(99.2)	(99.4)	(125.1)
Gain (loss) on modification/extinguishment of debt	(0.9)	(37.7)	10.0
Other income, net	0.0	0.8	0.0
(Provision) benefit for income taxes	0.0	0.0	0.0
Net income (loss)	58.6	(175.5)	(197.5)
Net income attributable to non-controlling partner	(16.2)	(25.3)	(24.2)
Net income (loss) attributable to parent	42.4	(200.8)	(221.7)
Service
Revenues:
Revenues	344.4	418.7	550.7
Costs of product/services sold (exclusive of items shown separately below):
Cost of Goods and Services Sold	44.2	49.9	55.5
Service | CMLP
Revenues:
Revenues	344.4	418.7	550.7
Costs of product/services sold (exclusive of items shown separately below):
Cost of Goods and Services Sold	44.2	49.9	55.5
Product
Revenues:
Revenues	3,309.7	3,462.2	1,969.8
Costs of product/services sold (exclusive of items shown separately below):
Cost of Goods and Services Sold	2,950.5	3,309.5	1,851.9
Product | CMLP
Revenues:
Revenues	3,309.7	3,462.2	1,969.8
Costs of product/services sold (exclusive of items shown separately below):
Cost of Goods and Services Sold	2,950.5	3,309.5	1,851.9
Gathering and Processing Segment | Service
Revenues:
Revenues	276.1	317.3	290.7
Gathering and Processing Segment | Service | CMLP
Revenues:
Revenues	276.1	317.3	290.7
Gathering and Processing Segment | Product
Revenues:
Revenues	670.5	1,369.1	825.5
Gathering and Processing Segment | Product | CMLP
Revenues:
Revenues	670.5	1,369.1	825.5
Marketing Supply and Logistics
Revenues:
Revenues	2,690.3	2,155.5	1,236.4
Costs of product/services sold (exclusive of items shown separately below):
Total costs of products/services sold	2,362.2	1,893.6	1,003.0
Operating expenses and other:
Operations and maintenance	50.8	63.4	59.7
General and administrative	0.0	0.0	0.0
Loss on long-lived assets, net	27.3	48.2	31.4
Goodwill impairment		38.8	109.1
Loss on contingent consideration		0.0
Earnings from unconsolidated affiliates, net	0.0	0.0	0.0
Marketing Supply and Logistics | CMLP
Revenues:
Revenues	2,690.3	2,155.5	1,236.4
Costs of product/services sold (exclusive of items shown separately below):
Total costs of products/services sold	2,362.2	1,893.6	1,003.0
Operating expenses and other:
Operations and maintenance	50.8	63.4	59.7
General and administrative	0.0	0.0	0.0
Loss on long-lived assets, net	27.3	48.2	31.4
Goodwill impairment		38.8	109.1
Loss on contingent consideration		0.0
Earnings from unconsolidated affiliates, net	0.0	0.0	0.0
Marketing Supply and Logistics | Service
Revenues:
Revenues	50.2	62.4	92.1
Marketing Supply and Logistics | Service | CMLP
Revenues:
Revenues	50.2	62.4	92.1
Marketing Supply and Logistics | Product
Revenues:
Revenues	2,639.2	2,093.1	1,144.3
Marketing Supply and Logistics | Product | CMLP
Revenues:
Revenues	2,639.2	2,093.1	1,144.3
Storage and Transportation
Revenues:
Revenues	17.1	37.2	165.3
Costs of product/services sold (exclusive of items shown separately below):
Total costs of products/services sold	0.2	0.3	5.1
Operating expenses and other:
Operations and maintenance	3.3	4.2	21.4
General and administrative	0.0	0.0	0.0
Loss on long-lived assets, net	0.0	0.0	32.2
Goodwill impairment		0.0	44.9
Loss on contingent consideration		57.0
Earnings from unconsolidated affiliates, net	30.8	28.9	11.2
Storage and Transportation | CMLP
Revenues:
Revenues	17.1	37.2	165.3
Costs of product/services sold (exclusive of items shown separately below):
Total costs of products/services sold	0.2	0.3	5.1
Operating expenses and other:
Operations and maintenance	3.3	4.2	18.3
General and administrative	0.0	0.0	0.0
Loss on long-lived assets, net	0.0	0.0	32.2
Goodwill impairment		0.0	44.9
Loss on contingent consideration		57.0
Earnings from unconsolidated affiliates, net	30.8	28.9	11.2
Storage and Transportation | Service
Revenues:
Revenues	17.1	37.2	165.3
Storage and Transportation | Service | CMLP
Revenues:
Revenues	$ 17.1	$ 37.2	$ 165.3