Schedule I - Crestwood Equity Partners LP - Parent Only - Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Condensed Financial Statements, Captions [Line Items]
Cash	$ 13.3	$ 14.0
Total current assets	604.7	405.9
Property, plant and equipment, net	2,779.4	2,917.1
Total assets	4,445.7	5,243.7
Accrued expenses	147.1	122.0
Total current liabilities	598.4	377.8
Other long-term liabilities	258.7	253.3
Total partners’ capital	1,099.6	1,655.4
Total liabilities and partners’ capital	4,445.7	5,243.7
Prepaid expenses and other current assets	14.8	13.4
Parent Company
Condensed Financial Statements, Captions [Line Items]
Cash	0.2	0.2	$ 0.2	$ 0.2
Total current assets	0.6	0.2
Property, plant and equipment, net	2.5	0.9
Investments in subsidiaries	1,100.1	1,655.7
Other assets	2.1	2.1
Total assets	1,105.3	1,658.9
Accounts payable	0.1	0.1
Accrued expenses	1.0	1.9
Total current liabilities	1.1	2.0
Other long-term liabilities	4.6	1.5
Total partners’ capital	1,099.6	1,655.4
Total liabilities and partners’ capital	1,105.3	1,658.9
Prepaid expenses and other current assets	$ 0.4	$ 0.0