Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Operating activities
Net loss	$ (166.6)	$ (192.1)	$ (2,303.7)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation, amortization and accretion	191.7	229.6	300.1
Amortization of debt-related deferred costs	7.2	6.9	8.9
Market adjustment on interest rate swaps	0.0	0.0	(0.5)
Unit-based compensation charges	25.5	19.2	19.7
Loss on long-lived assets, net	(65.6)	(65.6)	(821.2)
Goodwill impairment	38.8	162.6	1,406.3
Loss on contingent consideration	57.0	0.0	0.0
(Gain) loss on modification/extinguishment of debt	37.7	(10.0)	20.0
(Earnings) loss from unconsolidated affiliates, net, adjusted for cash distributions received	(0.1)	7.6	73.6
Deferred income taxes	(2.1)	(3.1)	(3.6)
Other	0.9	1.9	0.7
Changes in operating assets and liabilities:
Accounts receivable	(170.7)	(76.9)	119.7
Inventory	(9.9)	(22.5)	2.0
Prepaid expenses and other current assets	1.8	9.2	1.8
Accounts payable, accrued expenses and other liabilities	140.1	74.6	(128.0)
Reimbursements of property, plant and equipment	19.6	26.0	73.3
Change in price risk management activities, net	19.4	47.5	29.2
Net cash provided by operating activities	255.9	346.1	440.7
Investing activities
Acquisitions, net of cash acquired	0.0	(7.2)	0.0
Purchases of property, plant and equipment	(188.4)	(100.7)	(182.7)
Investment in unconsolidated affiliates	(58.0)	(12.4)	(42.0)
Capital distributions from unconsolidated affiliates	59.9	14.8	9.3
Net proceeds from sale of assets	225.2	972.7	2.7
Net cash provided by (used in) investing activities	38.7	867.2	(212.7)
Financing activities
Proceeds from the issuance of long-term debt	2,838.6	1,565.3	4,261.8
Payments on long-term debt	(2,913.9)	(2,536.3)	(4,113.0)
Payments on capital leases	(2.7)	(1.9)	(2.2)
Payments for debt-related deferred costs	(1.0)	(3.5)	(17.3)
Financing fees paid for early debt redemption	0.0	0.0	(13.6)
Payments for Repurchase of Redeemable Noncontrolling Interest	(202.7)	0.0	0.0
Distributions to partners	(167.6)	(219.8)	(171.5)
Distributions paid to non-controlling partners	(15.2)	(15.2)	(234.2)
Payments of Ordinary Dividends, Preferred Stock and Preference Stock	15.0	0.0	0.0
Net proceeds from issuance of preferred equity of subsidiary	(175.0)	0.0	0.0
Taxes paid for unit-based compensation vesting	(5.5)	(0.8)	(3.8)
Net proceeds from issuance of common units	15.2	0.0	0.0
Other	(0.1)	0.0	(1.3)
Net cash used in financing activities	(294.9)	(1,212.2)	(236.3)
Net change in cash	(0.3)	1.1	(8.3)
Cash at beginning of period	1.6	0.5	8.8
Cash at end of period	1.3	1.6	0.5
Supplemental disclosure of cash flow information
Cash paid during the period for interest	95.1	121.5	129.0
Cash paid during the period for income taxes	3.1	1.4	4.7
Supplemental schedule of noncash investing activities
Net change to property, plant and equipment through accounts payable and accrued expenses	(20.4)	(10.5)	(14.1)
Preferred Units, Class A
Financing activities
Net proceeds from issuance of preferred equity of subsidiary	0.0	0.0	(58.8)
CMLP
Operating activities
Net loss	(175.5)	(197.5)	(1,410.6)
Adjustments to reconcile net loss to net cash provided by operating activities:
Depreciation, amortization and accretion	202.7	240.5	278.5
Amortization of debt-related deferred costs	7.2	6.9	8.1
Unit-based compensation charges	25.5	19.2	18.1
Loss on long-lived assets, net	(65.6)	(65.6)	(227.8)
Goodwill impairment	38.8	162.6	1,149.1
Loss on contingent consideration	57.0	0.0	0.0
(Gain) loss on modification/extinguishment of debt	37.7	(10.0)	18.9
(Earnings) loss from unconsolidated affiliates, net, adjusted for cash distributions received	(0.1)	7.6	73.6
Deferred income taxes	0.0	0.2	(0.3)
Other	0.9	1.9	0.7
Changes in operating assets and liabilities:
Accounts receivable	(170.5)	(76.9)	119.4
Inventory	(9.9)	(22.5)	2.1
Prepaid expenses and other current assets	1.8	7.5	3.7
Accounts payable, accrued expenses and other liabilities	142.0	75.2	(119.8)
Reimbursements of property, plant and equipment	19.6	26.0	73.3
Change in price risk management activities, net	19.4	47.5	29.2
Net cash provided by operating activities	262.2	353.8	471.8
Investing activities
Acquisitions, net of cash acquired	0.0	(7.2)	0.0
Purchases of property, plant and equipment	(188.4)	(100.7)	(182.7)
Investment in unconsolidated affiliates	(58.0)	(12.4)	(41.8)
Capital distributions from unconsolidated affiliates	59.9	14.8	9.3
Net proceeds from sale of assets	225.2	972.7	2.7
Net cash provided by (used in) investing activities	38.7	867.2	(212.5)
Financing activities
Proceeds from the issuance of long-term debt	2,838.6	1,565.3	3,490.1
Payments on long-term debt	(2,913.9)	(2,536.1)	(2,960.9)
Payments on capital leases	(2.7)	(1.9)	(2.2)
Payments for debt-related deferred costs	(1.0)	(3.5)	(17.3)
Financing fees paid for early debt redemption	0.0	0.0	(13.6)
Payments for Repurchase of Redeemable Noncontrolling Interest	(202.7)	0.0
Distributions to partners	(189.2)	(242.8)	(819.5)
Net proceeds from issuance of preferred equity of subsidiary	(175.0)	0.0	0.0
Issuance of CMLP Class A preferred units	0.0	0.0	58.8
Taxes paid for unit-based compensation vesting	(5.5)	(0.8)	(2.1)
Other	0.2	0.0	(0.1)
Net cash used in financing activities	(301.2)	(1,219.8)	(266.8)
Net change in cash	(0.3)	1.2	(7.5)
Cash at beginning of period	1.3	0.1	7.6
Cash at end of period	1.0	1.3	0.1
Supplemental disclosure of cash flow information
Cash paid during the period for interest	95.1	121.5	118.2
Cash paid during the period for income taxes	0.6	0.7	0.6
Supplemental schedule of noncash investing activities
Net change to property, plant and equipment through accounts payable and accrued expenses	$ (20.4)	$ (10.5)	$ (14.1)