Basis of Presentation and Summary of Significant Accounting Policies (Goodwill, by Reporting Unit) (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Goodwill [Roll Forward]
Beginning Balance		$ 199.0
Goodwill Impairments during the Period		38.8	$ 162.6	$ 1,406.3
Ending Balance	$ 199.0	147.6	199.0
Goodwill, Other Increase (Decrease)		(12.6)	(723.9)
Fayetteville
Goodwill [Line Items]
Impairment of intangible assets				70.9
Goodwill [Roll Forward]
Beginning Balance		0.0	0.0
Goodwill Impairments during the Period		0.0	0.0	72.5
Ending Balance	0.0	0.0	0.0	0.0
Marcellus
Goodwill [Roll Forward]
Beginning Balance		0.0	8.6
Goodwill Impairments during the Period		0.0	8.6	0.0
Ending Balance	0.0	0.0	0.0	8.6
Arrow
Goodwill [Roll Forward]
Beginning Balance		45.9	45.9
Goodwill Impairments during the Period		0.0	0.0	0.0
Ending Balance	45.9	45.9	45.9	45.9
Northeast Storage and Transportation
Goodwill [Roll Forward]
Beginning Balance		0.0	726.3
Goodwill Impairments during the Period		0.0	0.0	0.0
Goodwill, Written off Related to Sale of Business Unit		(726.3)
Ending Balance	0.0	0.0	0.0	726.3
COLT
Goodwill [Roll Forward]
Beginning Balance		0.0	44.9
Goodwill Impairments during the Period		0.0	44.9	623.4
Ending Balance	0.0	0.0	0.0	44.9
West Coast
Goodwill [Line Items]
Impairment of intangible assets		0.8
Goodwill [Roll Forward]
Beginning Balance		2.4	0.0
Goodwill Impairments during the Period		2.4	0.0	85.9
Goodwill, Acquired During Period		2.4
Ending Balance	2.4	0.0	2.4	0.0
Supply and Logistics
Goodwill [Roll Forward]
Beginning Balance		101.7	167.2
Goodwill Impairments during the Period		0.0	65.5	99.0
Ending Balance	101.7	101.7	101.7	167.2
Storage and Terminals
Goodwill [Roll Forward]
Beginning Balance		36.4	50.5
Goodwill Impairments during the Period		36.4	14.1	53.7
Ending Balance	36.4	0.0	36.4	50.5
US Salt
Goodwill [Roll Forward]
Beginning Balance		12.6	12.6
Goodwill Impairments during the Period		0.0	0.0	0.0
Goodwill, Written off Related to Sale of Business Unit		(12.6)
Ending Balance	12.6	0.0	12.6	12.6
Trucking
Goodwill [Line Items]
Impairment of intangible assets			31.4
Goodwill [Roll Forward]
Beginning Balance		0.0	29.5
Goodwill Impairments during the Period		0.0	29.5	148.4
Ending Balance	0.0	0.0	0.0	29.5
Haynesville
Goodwill [Line Items]
Impairment of intangible assets				6.0
Barnett
Goodwill [Line Items]
Impairment of intangible assets				238.9
Goodwill [Roll Forward]
Beginning Balance		0.0	0.0
Goodwill Impairments during the Period		0.0	0.0	257.2
Ending Balance	0.0	0.0	0.0	0.0
Watkins Glen
Goodwill [Roll Forward]
Beginning Balance		0.0	0.0
Goodwill Impairments during the Period		0.0	0.0	66.2
Ending Balance	0.0	0.0	0.0	0.0
CMLP
Goodwill [Roll Forward]
Beginning Balance		199.0	1,085.5
Goodwill Impairments during the Period		38.8	162.6	1,149.1
Ending Balance	199.0	147.6	199.0	1,085.5
Goodwill, Other Increase (Decrease)		(12.6)	(723.9)
Crestwood Equity Partners LP
Goodwill [Roll Forward]
Beginning Balance		199.0	1,085.5
Goodwill Impairments during the Period		38.8	162.6	1,406.3
Ending Balance	199.0	147.6	199.0	1,085.5
Marketing Supply and Logistics
Goodwill [Line Items]
Consideration transferred	7.2
Goodwill [Roll Forward]
Beginning Balance		153.1
Goodwill Impairments during the Period		38.8	109.1	453.2
Ending Balance	153.1	101.7	153.1
Marketing Supply and Logistics | CMLP
Goodwill [Roll Forward]
Beginning Balance		153.1
Goodwill Impairments during the Period		38.8	109.1	$ 453.2
Ending Balance	$ 153.1	$ 101.7	$ 153.1