Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred:
Total deferred	$ 3.1	$ 3.6	$ 5.2
(Provision) benefit for income taxes	(0.3)	1.4	(1.1)
Crestwood Equity Partners LP
Income Tax Contingency [Line Items]
Deferred Tax Assets, Other	0.2	0.5
Deferred Tax Assets, Gross	0.2	0.5
Current:
Federal	(3.2)	(1.6)	(5.0)
State	(0.2)	(0.6)	(1.3)
Total current	(3.4)	(2.2)	(6.3)
Deferred:
Federal	3.0	2.9	5.3
State	0.1	0.7	(0.1)
Total deferred	3.1	3.6	5.2
(Provision) benefit for income taxes	(0.3)	1.4	(1.1)
Deferred tax liability:
Basis difference in stock of acquired company	(5.5)	(8.9)
Deferred Tax Liabilities, Gross	5.5	8.9
Total deferred tax liability	(5.3)	(8.4)
CMLP
Income Tax Contingency [Line Items]
Deferred Tax Assets, Other	0.0	0.0
Deferred Tax Assets, Gross	0.0	0.0
Current:
Federal	0.0	0.0	0.0
State	0.2	(0.3)	(0.2)
Total current	0.2	(0.3)	(0.2)
Deferred:
Federal	0.0	0.0	0.0
State	(0.2)	0.3	(0.7)
Total deferred	(0.2)	0.3	(0.7)
(Provision) benefit for income taxes	0.0	0.0	$ (0.9)
Deferred tax liability:
Basis difference in stock of acquired company	(0.7)	(0.4)
Deferred Tax Liabilities, Gross	0.7	0.4
Total deferred tax liability	$ (0.7)	$ (0.4)