Partners' Capital (Narrative) (Details) - USD ($) $ / shares in Units, $ in Millions																		1 Months Ended	3 Months Ended		9 Months Ended
	Nov. 14, 2016	Nov. 07, 2016	Oct. 20, 2016	Aug. 12, 2016	Aug. 05, 2016	May 13, 2016	May 06, 2016	Feb. 12, 2016	Feb. 05, 2016	Aug. 14, 2015	Aug. 07, 2015	May 15, 2015	May 08, 2015	Feb. 13, 2015	Feb. 06, 2015	Feb. 14, 2014	Feb. 07, 2014	Oct. 31, 2016	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Jun. 15, 2016	Dec. 31, 2015
Distribution Made to Limited Partner [Line Items]
Distribution Made to Limited Partner, Distribution Date				Aug. 12, 2016		May 13, 2016		Feb. 12, 2016		Aug. 14, 2015		May 15, 2015		Feb. 13, 2015
Distribution Made to Limited Partner, Date of Record					Aug. 05, 2016		May 06, 2016		Feb. 05, 2016		Aug. 07, 2015		May 08, 2015		Feb. 06, 2015
Incentive Distribution, Distribution																					$ 178.4	$ 77.2
Limited Partners' Capital Account, Distribution Amount																						31.4
Preferred Stock Dividends, Shares																					4,311,143
Net Income (Loss) Attributable to Noncontrolling Interest																			$ 6.1	$ (396.5)	$ 18.0	(642.7)
Dividends, Paid-in-kind																					39.3
Common Units Available for Issuance																							7,290,552
Payments of Ordinary Dividends, Noncontrolling Interest																					11.4	230.5
Distribution Made to Limited Partner, Cash Distributions Paid				$ 41.4		$ 41.4		$ 95.6		$ 25.7		$ 25.7		$ 25.8							$ 178.4	77.2
Preferred Units, Issued																			65,029,388		65,029,388			60,718,245
Crestwood Equity Partners LP
Distribution Made to Limited Partner [Line Items]
Incentive Distribution Rights, Ownership Percentage																					100.00%
Crestwood Midstream Partners LP
Distribution Made to Limited Partner [Line Items]
Distribution Made to Limited Partner, Distribution Date										Aug. 14, 2015		May 15, 2015				Feb. 13, 2015
Distribution Made to Limited Partner, Date of Record											Aug. 07, 2015		May 08, 2015				Feb. 06, 2015
Incentive Distribution, Distribution																					$ 196.4	$ 717.6
Preferred Stock Dividends, Shares																						1,271,935
Net Income (Loss) Attributable to Noncontrolling Interest																			$ 6.1	5.9	18.0	$ 17.2
Dividends, Paid-in-kind																						25.6
Payments of Ordinary Dividends, Noncontrolling Interest																					11.4	7.6
Proceeds from issuance of preferred limited partners units, gross																						60.0
Proceeds from Issuance of Preferred Limited Partners Units																					0.0	58.8
Distribution Made to Limited Partner, Cash Distributions Paid										$ 74.3		$ 74.3				$ 74.3						222.9
Distribution Made to General Partner, Cash Distributions Paid																					185.0	77.4
Crestwood Niobrara LLC
Distribution Made to Limited Partner [Line Items]
Net Income (Loss) Attributable to Noncontrolling Interest																			$ 6.1	$ 5.9	18.0	17.2
Payments of Ordinary Dividends, Noncontrolling Interest																					11.4	7.6
Non-Controlling Partners
Distribution Made to Limited Partner [Line Items]
Net Income (Loss) Attributable to Noncontrolling Interest																					$ 18.0
Subsequent Event
Distribution Made to Limited Partner [Line Items]
Distribution Made to Limited Partner, Distribution Date	Nov. 14, 2016
Distribution Made to Limited Partner, Date of Record		Nov. 07, 2016
Preferred Stock Dividends, Shares			1,504,027
Dividends, Paid-in-kind			$ 13.7
Payments of Ordinary Dividends, Noncontrolling Interest																		$ 3.8
Cash Distribution
Distribution Made to Limited Partner [Line Items]
Limited Partners' Capital Account, Distribution Amount																						222.9
Cash Distribution | Crestwood Midstream Partners LP
Distribution Made to Limited Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Paid																						$ 378.3
Cash Distribution | Subsequent Event
Distribution Made to Limited Partner [Line Items]
Distribution Made to Limited Partner, Distributions Declared, Per Unit	$ 0.6