Schedule I - Crestwood Equity Partners LP - Parent Only - Statement of Comprehensive Income (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	$ 319.9	$ 67.0	$ (166.6)
Change in fair value of Suburban Propane Partners, LP units	0.3	(0.7)	(0.8)
Comprehensive income (loss)	320.2	66.3	(167.4)
Parent Company
Condensed Financial Statements, Captions [Line Items]
Net income (loss)	285.1	50.8	(191.9)
Change in fair value of Suburban Propane Partners, LP units	0.3	(0.7)	(0.8)
Comprehensive income (loss)	$ 285.4	$ 50.1	$ (192.7)