Certain Balance Sheet Information (Property, Plant And Equipment) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 3,612.5	$ 2,598.1
Less: accumulated depreciation	703.4	568.4
Property, plant and equipment, net	2,909.1	2,029.7
Capitalized interests	14.4	5.0	$ 2.9
Finance Lease, Right-of-Use Asset	9.5
Capital Leases, Balance Sheet, Assets by Major Class, Net		9.7
Crestwood Equity Partners LP
Property, Plant and Equipment [Line Items]
Property, plant and equipment	3,612.5	2,598.1
Less: accumulated depreciation	703.4	568.4
Property, plant and equipment, net	2,909.1	2,029.7
Depreciation	139.5	123.6	135.9
Crestwood Equity Partners LP | Gathering systems and pipelines and related assets
Property, Plant and Equipment [Line Items]
Property, plant and equipment	1,017.8	758.6
Crestwood Equity Partners LP | Facilities and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment	1,797.7	1,230.7
Crestwood Equity Partners LP | Buildings, land, rights-of-way, storage rights and easements
Property, Plant and Equipment [Line Items]
Property, plant and equipment	370.6	331.7
Crestwood Equity Partners LP | Vehicles
Property, Plant and Equipment [Line Items]
Property, plant and equipment	27.7	17.9
Crestwood Equity Partners LP | Construction in process
Property, Plant and Equipment [Line Items]
Property, plant and equipment	368.7	230.8
Crestwood Equity Partners LP | Office furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, plant and equipment	30.0	28.4
CMLP
Property, Plant and Equipment [Line Items]
Property, plant and equipment	3,942.6	2,928.2
Less: accumulated depreciation	875.1	725.9
Property, plant and equipment, net	3,067.5	2,202.3
Depreciation	153.5	137.7	$ 150.0
CMLP | Gathering systems and pipelines and related assets
Property, Plant and Equipment [Line Items]
Property, plant and equipment	1,160.6	901.5
CMLP | Facilities and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment	1,982.8	1,415.9
CMLP | Buildings, land, rights-of-way, storage rights and easements
Property, Plant and Equipment [Line Items]
Property, plant and equipment	374.3	335.4
CMLP | Vehicles
Property, Plant and Equipment [Line Items]
Property, plant and equipment	26.0	16.1
CMLP | Construction in process
Property, Plant and Equipment [Line Items]
Property, plant and equipment	368.7	230.8
CMLP | Office furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, plant and equipment	$ 30.2	$ 28.5