Schedule I - Crestwood Equity Partners LP - Parent Only - Statement of Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	$ 67.0	$ (166.6)	$ (192.1)
Change in fair value of Suburban Propane Partners, LP units	(0.7)	(0.8)	0.8
Comprehensive income (loss)	66.3	(167.4)	(191.3)
Comprehensive income (loss) attributable to non-controlling partners	(16.2)	(25.3)	(24.2)
Comprehensive income (loss) attributable to Crestwood Equity Partners LP	50.1	(192.7)	(215.5)
Parent Company
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	67.0	(166.6)	(192.1)
Change in fair value of Suburban Propane Partners, LP units	(0.7)	(0.8)	0.8
Comprehensive income (loss)	66.3	(167.4)	(191.3)
Comprehensive income (loss) attributable to non-controlling partners	(16.2)	(25.3)	(24.2)
Comprehensive income (loss) attributable to Crestwood Equity Partners LP	$ 50.1	$ (192.7)	$ (215.5)