Segments (Reconciliation of Net Income (Loss) to EBITDA) (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) segment	Sep. 30, 2019 USD ($)
Segment Reporting, Other Significant Reconciling Item [Line Items]
Number of Operating Segments | segment			3
Net income (loss)	$ 4.6	$ 33.6	$ (43.1)	$ 272.7
Interest and debt expense, net	33.7	30.6	100.3	83.3
Provision (benefit) for income taxes	0.0	0.0	(0.1)	0.3
Depreciation, amortization and accretion	60.8	51.5	177.9	140.6
EBITDA	99.1	115.7	235.0	496.9
Crestwood Midstream Partners LP
Segment Reporting, Other Significant Reconciling Item [Line Items]
Net income (loss)	2.3	31.2	(50.1)	265.7
Interest and debt expense, net	33.7	30.6	100.3	83.3
Provision (benefit) for income taxes	0.0	(0.1)	(0.2)	0.2
Depreciation, amortization and accretion	64.2	55.1	188.4	151.2
EBITDA	$ 100.2	$ 116.8	$ 238.4	$ 500.4