Schedule I - Crestwood Equity Partners LP - Parent Only - Statement of Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Condensed Financial Statements, Captions [Line Items]
Revenues	$ 3,654.1	$ 3,880.9	$ 2,520.5
Operating income (loss)	113.5	(79.4)	(108.7)
Other income, net	0.4	1.3	0.5
Net income (loss)	67.0	(166.6)	(192.1)
Net income attributable to non-controlling partners in subsidiary	16.2	25.3	24.2
Net income (loss) attributable to parent	50.8	(191.9)	(216.3)
Parent Company
Condensed Financial Statements, Captions [Line Items]
Revenues	0.0	0.0	0.0
Costs and Expenses	6.1	6.7	6.0
Operating income (loss)	(6.1)	(6.7)	(6.0)
Loss from unconsolidated affiliates	72.7	(160.4)	(186.6)
Other income, net	0.4	0.5	0.5
Net income (loss)	67.0	(166.6)	(192.1)
Net income attributable to non-controlling partners in subsidiary	16.2	25.3	24.2
Net income (loss) attributable to parent	$ 50.8	$ (191.9)	$ (216.3)