Schedule I - Crestwood Equity Partners LP - Parent Only - Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Financial Statements, Captions [Line Items]
Cash	$ 0.9	$ 1.3
Total current assets	379.3	530.5
Property, plant and equipment, net	2,029.7	1,820.8
Total assets	4,294.5	4,284.9
Accrued expenses	112.4	105.9
Total current liabilities	332.1	505.1
Other long-term liabilities	173.6	104.7
Total partners’ capital	2,033.8	2,180.5
Total liabilities and partners’ capital	4,294.5	4,284.9
Parent Company
Condensed Financial Statements, Captions [Line Items]
Cash	0.2	0.3	$ 0.3	$ 0.4
Total current assets	0.2	0.3
Property, plant and equipment, net	1.1	1.2
Intangible assets, net	0.0	1.4
Investments in subsidiaries	1,854.7	2,005.1
Other assets	2.8	3.5
Total assets	1,858.8	2,011.5
Accounts payable	2.6	2.7
Accrued expenses	1.1	1.2
Total current liabilities	3.7	3.9
Other long-term liabilities	2.6	2.1
Total partners’ capital	1,852.5	2,005.5
Total liabilities and partners’ capital	$ 1,858.8	$ 2,011.5