Schedule I - Crestwood Equity Partners LP - Parent Only - Statement of Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Financial Statements, Captions [Line Items]
Revenues	$ 3,181.9	$ 3,654.1	$ 3,880.9
Operating income (loss)	402.2	113.5	(79.4)
Other income, net	0.6	0.4	1.3
Net income (loss)	319.9	67.0	(166.6)
Parent Company
Condensed Financial Statements, Captions [Line Items]
Revenues	0.0	0.0	0.0
Costs and Expenses	5.3	6.1	6.7
Operating income (loss)	(5.3)	(6.1)	(6.7)
Loss from unconsolidated affiliates	290.0	56.5	(185.7)
Other income, net	0.4	0.4	0.5
Net income (loss)	$ 285.1	$ 50.8	$ (191.9)