Consolidated Statements of Operations - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues:
Revenues	$ 3,181.9	$ 3,654.1	$ 3,880.9
Costs of product/services sold (exclusive of items shown separately below):
Product costs - related party (Note 16)	45.4	134.7	15.3
Total costs of products/services sold	2,544.9	3,129.4	3,374.7
Operating expenses and other:
Operations and maintenance	138.8	125.8	136.0
General and administrative	103.4	88.1	96.5
Depreciation, amortization and accretion	195.8	168.7	191.7
Loss on long-lived assets, net	6.2	28.6	65.6
Gain on acquisition	(209.4)	0.0	0.0
Goodwill impairment	0.0	0.0	38.8
Loss on contingent consideration	0.0	0.0	57.0
Total expenses	234.8	411.2	585.6
Operating income (loss)	402.2	113.5	(79.4)
Earnings from unconsolidated affiliates, net	32.8	53.3	47.8
Interest and debt expense, net	(115.4)	(99.2)	(99.4)
Loss on modification/extinguishment of debt	0.0	(0.9)	(37.7)
Other income, net	0.6	0.4	1.3
Income (loss) before income taxes	320.2	67.1	(167.4)
(Provision) benefit for income taxes	(0.3)	(0.1)	0.8
Net income (loss)	319.9	67.0	(166.6)
Net income attributable to non-controlling partner	34.8	16.2	25.3
Net income (loss) attributable to parent	285.1	50.8	(191.9)
Net income attributable to preferred units	60.1	60.1	62.5
Net income (loss) attributable to partners	225.0	(9.3)	(254.4)
Subordinated unitholders’ interest in net income	1.4	0.0	0.0
Common unitholders’ interest in net income (loss)	$ 223.6	$ (9.3)	$ (254.4)
Net income (loss) per limited partner unit:
Basic (dollars per unit)	$ 3.11	$ (0.13)	$ (3.64)
Diluted (dollars per unit)	$ 2.93	$ (0.13)	$ (3.64)
Weighted-average limited partners’ units outstanding:
Basic (units)	71.8	71.2	69.8
Dilutive units (units)	5.1	0.0	0.0
Diluted (units)	76.9	71.2	69.8
CMLP
Revenues:
Revenues	$ 3,181.9	$ 3,654.1	$ 3,880.9
Costs of product/services sold (exclusive of items shown separately below):
Product costs - related party (Note 16)	45.4	134.7	15.3
Total costs of products/services sold	2,544.9	3,129.4	3,374.7
Operating expenses and other:
Operations and maintenance	138.8	125.8	136.0
General and administrative	98.2	83.5	93.1
Depreciation, amortization and accretion	209.9	181.4	202.7
Loss on long-lived assets, net	6.2	28.6	65.6
Gain on acquisition	(209.4)	0.0	0.0
Goodwill impairment	0.0	0.0	38.8
Loss on contingent consideration	0.0	0.0	57.0
Total expenses	243.7	419.3	593.2
Operating income (loss)	393.3	105.4	(87.0)
Earnings from unconsolidated affiliates, net	32.8	53.3	47.8
Interest and debt expense, net	(115.4)	(99.2)	(99.4)
Loss on modification/extinguishment of debt	0.0	(0.9)	(37.7)
Other income, net	0.2	0.0	0.8
Income (loss) before income taxes	310.9	58.6	(175.5)
(Provision) benefit for income taxes	(0.3)	0.0	0.0
Net income (loss)	310.6	58.6	(175.5)
Net income attributable to non-controlling partner	34.8	16.2	25.3
Net income (loss) attributable to parent	275.8	42.4	(200.8)
Service
Revenues:
Revenues	426.6	344.4	418.7
Related party (Note 16)	0.0	1.0	1.8
Costs of product/services sold (exclusive of items shown separately below):
Product and service costs	29.8	44.2	49.9
Service | CMLP
Revenues:
Revenues	426.6	344.4	418.7
Related party (Note 16)	0.0	1.0	1.8
Costs of product/services sold (exclusive of items shown separately below):
Product and service costs	29.8	44.2	49.9
Product
Revenues:
Revenues	2,755.3	3,309.7	3,462.2
Related party (Note 16)	2.9	0.0	0.0
Costs of product/services sold (exclusive of items shown separately below):
Product and service costs	2,469.7	2,950.5	3,309.5
Product | CMLP
Revenues:
Revenues	2,755.3	3,309.7	3,462.2
Related party (Note 16)	2.9	0.0	0.0
Costs of product/services sold (exclusive of items shown separately below):
Product and service costs	2,469.7	2,950.5	3,309.5
Gathering and Processing Segment | Service
Revenues:
Revenues	380.0	276.1	317.3
Gathering and Processing Segment | Service | CMLP
Revenues:
Revenues	380.0	276.1	317.3
Gathering and Processing Segment | Product
Revenues:
Revenues	455.8	670.5	1,369.1
Gathering and Processing Segment | Product | CMLP
Revenues:
Revenues	455.8	670.5	1,369.1
Marketing Supply and Logistics
Revenues:
Revenues		2,690.3
Marketing Supply and Logistics | Service
Revenues:
Revenues	26.2	50.2	62.4
Marketing Supply and Logistics | Service | CMLP
Revenues:
Revenues	26.2	50.2	62.4
Marketing Supply and Logistics | Product
Revenues:
Revenues	2,296.6	2,639.2	2,093.1
Marketing Supply and Logistics | Product | CMLP
Revenues:
Revenues	2,296.6	2,639.2	2,093.1
Storage and Transportation | Service
Revenues:
Revenues	20.4	17.1	37.2
Storage and Transportation | Service | CMLP
Revenues:
Revenues	$ 20.4	$ 17.1	$ 37.2