Consolidated Statement of Partners' Capital - USD ($) $ in Millions	Total	CMLP	Common Unit Capital	Common Unit Capital CMLP	Preferred Units	Preferred Units CMLP	Limited Partners	Limited Partners CMLP	Non-Controlling Partners	Non-Controlling Partners CMLP	Partners' Capital [Member]	Preferred Units, Class A	Preferred Units, Class A Preferred Units	Preferred Units, Class A Limited Partners	Preferred Units, Class A Non-Controlling Partners	Subordinated units	Common units	Preferred Units
Common Unit, Outstanding																400,000	18,200,000
Preferred units, outstanding																		0
Partners' Capital Account, Units, Acquisitions																	49,900,000	59,300,000
Balance at the beginning of the period at Dec. 31, 2014	$ 5,584.5	$ 5,320.4			$ 0.0	$ 447.7	$ 776.2	$ 4,701.0	$ 4,808.3	$ 171.7
Increase (Decrease) in Partners' Capital [Roll Forward]
Unit-based compensation charges	19.7	18.1			0.0	0.0	5.7	18.1	14.0	0.0
Partners' Capital Account, Units, Unit-based Compensation																	100,000
Taxes paid for unit-based compensation vesting	(3.7)	(2.1)			0.0	0.0	(1.6)	(2.1)	(2.1)	0.0
Distributions to partners	(405.7)	(819.5)			0.0	0.0	(171.5)	(808.2)	(234.2)	(11.3)
Issuance of CMLP Class A preferred units		58.8				58.8		0.0		0.0
Partners' Capital Account, Exchanges and Conversions	0.0	0.0			529.6	(529.6)	3,294.8	529.6	(3,824.4)	0.0
Issuance of preferred equity of subsidiary												$ 58.8	$ 0.0	$ 0.0	$ 58.8
Change in fair value of Suburban Propane Partners, LP units	(2.7)				0.0		(2.7)		0.0
Other	(0.3)				0.0		(0.2)		(0.1)
Net loss	(2,303.7)	(1,410.6)			6.2	23.1	(1,673.1)	(1,456.8)	(636.8)	23.1
Balance at the end of the period at Dec. 31, 2015	2,946.9	3,165.1			535.8	0.0	2,227.6	2,981.6	183.5	183.5
Common Unit, Outstanding																400,000	68,200,000
Preferred units, outstanding																		60,700,000
Increase (Decrease) in Partners' Capital [Roll Forward]
Preferred units, issued													1,400,000
Unit-based compensation charges	19.2	19.2			0.0	0.0	19.2	19.2	0.0	0.0
Partners' Capital Account, Units, Unit-based Compensation																	900,000
Taxes paid for unit-based compensation vesting	(0.8)	(0.8)			0.0	0.0	(0.8)	(0.8)	0.0	0.0
Distributions to partners	(235.0)	(242.8)			0.0	0.0	(219.8)	(227.6)	(15.2)	(15.2)
Issuance of CMLP Class A preferred units		0.0
Preferred Stock Dividends, Shares																		5,800,000
Change in fair value of Suburban Propane Partners, LP units	0.8				0.0		0.8		0.0
Net loss	(192.1)	(197.5)			28.7	0.0	(245.0)	(221.7)	24.2	24.2
Balance at the end of the period at Dec. 31, 2016	$ 2,539.0	2,743.2			564.5	0.0	1,782.0	2,550.7	192.5	192.5
Common Unit, Outstanding																400,000	69,100,000
Preferred units, outstanding	66,533,415																	66,500,000
Increase (Decrease) in Partners' Capital [Roll Forward]
Preferred units, issued	66,533,415
Proceeds from the issuance of common units			$ 15.2		0.0				0.0		$ 15.2
Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests	$ 0.0	(202.7)	0.0		0.0				(202.7)	(202.7)	(202.7)
Partners' Capital Account, Units, Sold in Public Offering	633,271																600,000
Unit-based compensation charges	$ 25.5	25.5			0.0	0.0	25.5	25.5	0.0	0.0
Partners' Capital Account, Units, Unit-based Compensation																	800,000
Taxes paid for unit-based compensation vesting	(5.5)	(5.5)			0.0	0.0	(5.5)	(5.5)	0.0	0.0
Shares Paid for Tax Withholding for Share Based Compensation																	(200,000)
Distributions to partners	(197.8)	(189.2)			(15.0)	0.0	(167.6)	(174.0)	(15.2)	(15.2)
Issuance of CMLP Class A preferred units		0.0
Issuance of preferred equity of subsidiary	0.0	175.0	0.0		0.0				175.0	175.0	175.0
Preferred Stock Dividends, Shares																		4,800,000
Change in fair value of Suburban Propane Partners, LP units	(0.8)				0.0		(0.8)		0.0
Other		(0.4)	$ (0.9)	$ (0.5)	0.0	0.0			0.1	0.1	$ (0.8)
Net loss	(166.6)	(175.5)			62.5	0.0	(254.4)	(200.8)	25.3	25.3
Balance at the end of the period at Dec. 31, 2017	$ 2,180.5	$ 2,370.4			$ 612.0	$ 0.0	$ 1,393.5	$ 2,195.4	$ 175.0	$ 175.0
Common Unit, Outstanding																400,000	70,300,000
Preferred units, outstanding	71,257,445																	71,300,000
Increase (Decrease) in Partners' Capital [Roll Forward]
Preferred units, issued	71,257,445