Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred:
Total deferred	$ 0.0	$ 0.7	$ 2.1
(Provision) benefit for income taxes	(0.3)	(0.1)	0.8
Crestwood Equity Partners LP
Income Tax Contingency [Line Items]
Deferred Tax Assets, Gross	0.2	0.2
Current:
Federal	(0.1)	(0.5)	(1.1)
State	(0.2)	(0.3)	(0.2)
Total current	(0.3)	(0.8)	(1.3)
Deferred:
Federal	0.1	0.5	2.1
State	(0.1)	0.2	0.0
Total deferred	0.0	0.7	2.1
(Provision) benefit for income taxes	(0.3)	(0.1)	0.8
Deferred tax asset:
Total deferred tax liability	(2.8)	(2.8)
Deferred tax liability:
Total deferred tax liability(1)	(2.6)	(2.6)
CMLP
Income Tax Contingency [Line Items]
Deferred Tax Assets, Gross	0.0	0.0
Current:
Federal	0.1	0.1	0.0
State	(0.2)	(0.2)	0.0
Total current	(0.1)	(0.1)	0.0
Deferred:
Federal	0.0	0.0	0.0
State	(0.2)	0.1	0.0
Total deferred	(0.2)	0.1	0.0
(Provision) benefit for income taxes	(0.3)	0.0	$ 0.0
Deferred tax asset:
Total deferred tax liability	(0.7)	(0.6)
Deferred tax liability:
Total deferred tax liability(1)	$ (0.7)	$ (0.6)