Consolidated Statements of Cash Flows - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating activities
Net income (loss)	$ 67.0	$ (166.6)	$ (192.1)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, amortization and accretion	168.7	191.7	229.6
Amortization of deferred financing costs	6.8	7.2	6.9
Unit-based compensation charges	28.5	25.5	19.2
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
(Gain) loss on modification/extinguishment of debt	0.9	37.7	(10.0)
Earnings from unconsolidated affiliates, net, adjusted for cash distributions received	0.5	(0.1)	7.6
Deferred income taxes	(0.7)	(2.1)	(3.1)
Other	0.2	0.9	1.9
Changes in operating assets and liabilities:
Accounts receivable	167.8	(170.7)	(76.9)
Inventory	(24.1)	(9.9)	(22.5)
Prepaid expenses and other current assets	(3.1)	1.8	9.2
Accounts payable, accrued expenses and other liabilities	(138.6)	140.1	74.6
Reimbursements of property, plant and equipment	21.7	19.6	26.0
Change in price risk management activities, net	(70.6)	19.4	47.5
Net cash provided by operating activities	253.6	255.9	346.1
Investing activities
Acquisitions, net of cash acquired	0.0	0.0	(7.2)
Purchases of property, plant and equipment	(305.5)	(188.4)	(100.7)
Investment in unconsolidated affiliates	(64.4)	(58.0)	(12.4)
Capital distributions from unconsolidated affiliates	49.2	59.9	14.8
Net proceeds from sale of assets	79.5	225.2	972.7
Net cash provided by (used in) investing activities	(241.2)	38.7	867.2
Financing activities
Proceeds from the issuance of long-term debt	2,274.8	2,838.6	1,565.3
Payments on long-term debt	(2,015.7)	(2,913.9)	(2,536.3)
Payments on capital leases	(1.6)	(2.7)	(1.9)
Payments for deferred financing costs	(5.7)	(1.0)	(3.5)
Redemption of non-controlling interest	0.0	(202.7)	0.0
Net proceeds from issuance of non-controlling interest	0.0	(175.0)	0.0
Distributions to partners	(170.8)	(167.6)	(219.8)
Distributions to non-controlling partner	(9.9)	(15.2)	(15.2)
Distributions to preferred unitholders	60.1	15.0	0.0
Net proceeds from issuance of common units	0.0	15.2	0.0
Taxes paid for unit-based compensation vesting	(7.4)	(5.5)	(0.8)
Other	(0.1)	(0.1)	0.0
Net cash provided by (used in) financing activities	3.5	(294.9)	(1,212.2)
Net change in cash and restricted cash	15.9	(0.3)	1.1
Cash and restricted cash at beginning of period	1.3	1.6	0.5
Cash and restricted cash at end of period	17.2	1.3	1.6
Supplemental disclosure of cash flow information
Cash paid during the period for interest	97.4	95.1	121.5
Cash paid during the period for income taxes	3.1	3.1	1.4
Supplemental schedule of noncash investing activities
Net change to property, plant and equipment through accounts payable and accrued expenses	0.3	(20.4)	(10.5)
CMLP
Operating activities
Net income (loss)	58.6	(175.5)	(197.5)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, amortization and accretion	181.4	202.7	240.5
Amortization of deferred financing costs	6.8	7.2	6.9
Unit-based compensation charges	28.5	25.5	19.2
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
(Gain) loss on modification/extinguishment of debt	0.9	37.7	(10.0)
Earnings from unconsolidated affiliates, net, adjusted for cash distributions received	0.5	(0.1)	7.6
Deferred income taxes	(0.1)	0.0	0.2
Other	0.2	0.9	1.9
Changes in operating assets and liabilities:
Accounts receivable	169.3	(170.5)	(76.9)
Inventory	(24.1)	(9.9)	(22.5)
Prepaid expenses and other current assets	(3.1)	1.8	7.5
Accounts payable, accrued expenses and other liabilities	(138.1)	142.0	75.2
Reimbursements of property, plant and equipment	21.7	19.6	26.0
Change in price risk management activities, net	(70.6)	19.4	47.5
Net cash provided by operating activities	260.5	262.2	353.8
Investing activities
Acquisitions, net of cash acquired	0.0	0.0	(7.2)
Purchases of property, plant and equipment	(305.5)	(188.4)	(100.7)
Investment in unconsolidated affiliates	(64.4)	(58.0)	(12.4)
Capital distributions from unconsolidated affiliates	49.2	59.9	14.8
Net proceeds from sale of assets	79.5	225.2	972.7
Net cash provided by (used in) investing activities	(241.2)	38.7	867.2
Financing activities
Proceeds from the issuance of long-term debt	2,274.8	2,838.6	1,565.3
Payments on long-term debt	(2,015.7)	(2,913.9)	(2,536.1)
Payments on capital leases	(1.6)	(2.7)	(1.9)
Payments for deferred financing costs	(5.7)	(1.0)	(3.5)
Redemption of non-controlling interest	0.0	(202.7)	0.0
Net proceeds from issuance of non-controlling interest	0.0	(175.0)	0.0
Distributions to partners	(238.4)	(174.0)	(227.6)
Distributions to non-controlling partner	(9.9)	(15.2)	(15.2)
Taxes paid for unit-based compensation vesting	(7.4)	(5.5)	(0.8)
Other	0.1	0.2	0.0
Net cash provided by (used in) financing activities	(3.8)	(301.2)	(1,219.8)
Net change in cash and restricted cash	15.5	(0.3)	1.2
Cash and restricted cash at beginning of period	1.0	1.3	0.1
Cash and restricted cash at end of period	16.5	1.0	1.3
Supplemental disclosure of cash flow information
Cash paid during the period for interest	97.4	95.1	121.5
Cash paid during the period for income taxes	0.6	0.6	0.7
Supplemental schedule of noncash investing activities
Net change to property, plant and equipment through accounts payable and accrued expenses	$ 0.3	$ (20.4)	$ (10.5)