Consolidated Statement of Partners' Capital - USD ($) $ in Millions	Total	CMLP	Crestwood Marcellus Midstream LLC	Arrow Midstream Holdings, LLC	Arrow Midstream Holdings, LLC CMLP	Class D Units	Class C Units	Preferred Units	Preferred Units CMLP	Preferred Units Crestwood Marcellus Midstream LLC	Preferred Units Arrow Midstream Holdings, LLC	Preferred Units Arrow Midstream Holdings, LLC CMLP	Preferred Units Class D Units	Preferred Units Class C Units	Limited Partners	Limited Partners CMLP	Limited Partners Crestwood Marcellus Midstream LLC	Limited Partners Arrow Midstream Holdings, LLC	Limited Partners Arrow Midstream Holdings, LLC CMLP	Limited Partners Class D Units	Limited Partners Class C Units	Non-Controlling Partners	Non-Controlling Partners CMLP	Non-Controlling Partners Crestwood Marcellus Midstream LLC	Non-Controlling Partners Arrow Midstream Holdings, LLC	Non-Controlling Partners Arrow Midstream Holdings, LLC CMLP	Non-Controlling Partners Class D Units	Non-Controlling Partners Class C Units	Preferred Units, Class A	Preferred Units, Class A CMLP	Preferred Units, Class A Preferred Units	Preferred Units, Class A Limited Partners	Preferred Units, Class A Non-Controlling Partners
Balance at the beginning of the period at Dec. 31, 2012	$ 1,550.7	$ 859.7						$ 0.0	$ 0.0						$ 31.7	$ 859.7						$ 1,519.0	$ 0.0
Increase (Decrease) in Partners' Capital [Roll Forward]
Proceeds from the issuance of common units	714.0	714.0		$ 200.0	$ 200.0			0.0	0.0		$ 0.0	$ 0.0			0.0	714.0		$ 0.0	$ 200.0			714.0	0.0		$ 200.0	$ 0.0
Net proceeds from issuance of common units by subsidiaries						$ 0.0	$ 0.0						$ 0.0	$ 0.0						$ (126.3)	$ 0.6						$ 126.3	$ (0.6)
Contributions from partner	10.0	15.5						0.0	0.0						0.0	15.5						10.0	0.0
Unit-based compensation charges	17.4	15.8						0.0	0.0						1.7	15.8						15.7	0.0
Taxes paid for unit-based compensation vesting	(8.3)	(5.5)						0.0	0.0						(2.8)	(5.5)						(5.5)	0.0
Distributions to partners	(271.1)	(419.7)					$ 0.0	0.0	0.0					$ 0.0	(56.6)	(419.7)					$ (0.1)	(214.5)	0.0					$ 0.1
Issuance of CMLP Class A preferred units																														$ 0.0
Issuance of preferred equity of subsidiary	96.1	96.1						0.0	0.0						0.0	0.0						96.1	96.1
Exchange of Crestwood Midstream Partners LP units for CEQP units	0.0							0.0							182.3							(182.3)
Invested capital from Legacy Inergy, net of debt (Note 3)	3,379.4	3,827.8						0.0	0.0						697.1	3,827.8						2,682.3	0.0
Distribution for additional interest in Crestwood Marcellus Midstream LLC	(129.0)							0.0							(129.0)							0.0
Gain (loss) on issuance of subsidiary units	0.0							0.0							(12.6)							12.6
Acquisition of non-controlling interest			$ 0.0							$ 0.0							$ 238.9							$ (238.9)
Change in fair value of Suburban Propane Partners, LP units	(0.1)							0.0							(0.1)							0.0
Other	0.1							0.0							0.1							0.0
Net loss	(50.6)	(12.4)						0.0	0.0						6.7	(17.3)						(57.3)	4.9
Balance at the end of the period at Dec. 31, 2013	5,508.6	5,291.3						0.0	0.0						831.6	5,190.3						4,677.0	101.0
Increase (Decrease) in Partners' Capital [Roll Forward]
Contributions from partner	(15.3)	(15.3)						0.0							(10.5)	(15.3)						(4.8)	0.0
Unit-based compensation charges	21.3	18.1						0.0	0.0						3.9	18.1						17.4	0.0
Taxes paid for unit-based compensation vesting	(3.9)	(1.6)						0.0	0.0						(2.3)	(1.6)						(1.6)	0.0
Distributions to partners	(399.0)	(470.5)						0.0	0.0						(102.5)	(470.5)						(296.5)	0.0
Issuance of CMLP Class A preferred units		430.5							430.5							0.0							0.0							430.5
Issuance of preferred equity of subsidiary	53.9	53.9						0.0	0.0						0.0	0.0						53.9	53.9						$ 430.5		$ 0.0	$ 0.0	$ 430.5
Change in fair value of Suburban Propane Partners, LP units	(0.5)							0.0							(0.5)							0.0
Other	(0.7)	(0.7)						0.0	0.0						0.1	(0.7)						(0.8)	0.0
Net loss	(10.4)	14.7						0.0	17.2						56.4	(19.3)						(66.8)	16.8
Balance at the end 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
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	58.8						0.0	0.0						(58.8)	0.0							$ 58.8
Partners' Capital Account, Exchanges and Conversions		0.0							(529.6)							529.6							0.0
Acquisition of non-controlling interest	0.0							529.6							3,294.8							(3,824.4)
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