Consolidated Statement of Partners' Capital - USD ($) $ in Millions	Total	CMLP	Preferred Units	Common Unit Capital	Common Unit Capital CMLP	Limited Partners	Limited Partners CMLP	Non-Controlling Partners	Non-Controlling Partners CMLP	Partners' Capital [Member]	Subordinated units	Common units	Preferred Units
Common Unit, Outstanding											400,000	68,200,000
Preferred units, outstanding													60,700,000
Balance at the beginning of the period at Dec. 31, 2015		$ 3,165.1	$ 535.8			$ 2,227.6	$ 2,981.6	$ 183.5	$ 183.5	$ 2,946.9
Increase (Decrease) in Partners' Capital [Roll Forward]
Unit-based compensation charges		19.2	0.0			19.2	19.2	0.0	0.0	19.2
Partners' Capital Account, Units, Unit-based Compensation												900,000
Taxes paid for unit-based compensation vesting		(0.8)	0.0			(0.8)	(0.8)	0.0	0.0	(0.8)
Distributions to partners		(242.8)	0.0			(219.8)	(227.6)	(15.2)	(15.2)	(235.0)
Preferred Stock Dividends, Shares													5,800,000
Change in fair value of Suburban Propane Partners, LP units			0.0			0.8		0.0		0.8
Net income (loss)	$ (192.1)	(197.5)	28.7			(245.0)	(221.7)	24.2	24.2	(192.1)
Balance at the end of the period at Dec. 31, 2016		2,743.2	564.5			1,782.0	2,550.7	192.5	192.5	2,539.0
Common Unit, Outstanding											400,000	69,100,000
Preferred units, outstanding													66,500,000
Increase (Decrease) in Partners' Capital [Roll Forward]
Proceeds from the issuance of common units			0.0	$ 15.2				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	0.0			25.5	25.5	0.0	0.0	25.5
Partners' Capital Account, Units, Unit-based Compensation												800,000
Taxes paid for unit-based compensation vesting		(5.5)	0.0			(5.5)	(5.5)	0.0	0.0	(5.5)
Shares Paid for Tax Withholding for Share Based Compensation												(200,000)
Distributions to partners		(189.2)	(15.0)			(167.6)	(174.0)	(15.2)	(15.2)	(197.8)
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			0.0			(0.8)		0.0		(0.8)
Other		(0.4)	0.0	(0.9)	$ (0.5)			0.1	0.1	(0.8)
Net income (loss)	(166.6)	(175.5)	62.5			(254.4)	(200.8)	25.3	25.3	(166.6)
Balance at the end of the period at Dec. 31, 2017	$ 2,180.5	2,370.4	612.0			1,393.5	2,195.4	175.0	175.0	2,180.5
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
Proceeds from the issuance of common units								0.0
Partners' Capital Account, Units, Sold in Public Offering	0
Unit-based compensation charges		28.5	0.0			28.5	28.5	(9.9)	0.0	28.5
Partners' Capital Account, Units, Unit-based Compensation												1,100,000
Taxes paid for unit-based compensation vesting		(7.4)	0.0			(7.4)	(7.4)	0.0	0.0	(7.4)
Shares Paid for Tax Withholding for Share Based Compensation												(200,000)
Distributions to partners		(248.3)	(60.1)			(170.8)	(238.4)		(9.9)	(240.8)
Change in fair value of Suburban Propane Partners, LP units			0.0			(0.7)		0.0		(0.7)
Other		0.2	0.0	(0.8)	0.2			0.0	0.0	(0.8)
Net income (loss)	$ 67.0	58.6	60.1			(9.3)	42.4	16.2	16.2	67.0
Balance at the end of the period at Dec. 31, 2018	$ 2,033.8	2,209.5	612.0			$ 1,240.5	$ 2,028.2	181.3	181.3	2,033.8
Common Unit, Outstanding											400,000	71,200,000
Preferred units, outstanding	71,257,445												71,300,000
Increase (Decrease) in Partners' Capital [Roll Forward]
Preferred units, issued	71,257,445
Cumulative Effect of New Accounting Principle in Period of Adoption		$ 7.5	$ 0.0	$ 7.5	$ 7.5			$ 0.0	$ 0.0	$ 7.5