Schedule I - Crestwood Equity Partners LP - Parent Only - Balance Sheet (Details) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Jun. 30, 2012
Condensed Financial Statements, Captions [Line Items]
Cash	$ 0.5	$ 8.8	$ 5.2	$ 0.1
Total current assets	335.8	538.1
Property, plant and equipment, net	3,310.8	3,893.8
Total assets	5,803.7	8,461.4
Accrued expenses	105.6	154.6
Current portion of long-term debt	1.1	3.7
Total current liabilities	258.2	424.9
Long-term debt, less current portion (Note 9)	2,542.7	2,392.8
Other long-term liabilities	47.5	47.2
Total partners’ capital	2,946.9	5,584.5	5,508.6	1,550.7
Total liabilities and partners’ capital	5,803.7	8,461.4
Parent Company
Condensed Financial Statements, Captions [Line Items]
Cash	0.4	3.7	$ 0.1	$ 0.0
Accounts Payable, Trade	1.8	0.0
Accounts receivable - intercompany	0.0	3.2
Total current assets	2.2	6.9
Property, plant and equipment, net	1.5	2.5
Intangible assets	7.8	1.7
Investment in subsidiaries	2,757.7	5,799.5
Other assets	3.5	0.0
Total assets	2,772.7	5,810.6
Accounts payable	2.6	0.0
Accrued expenses	2.3	1.9
Current portion of long-term debt	0.2	3.0
Total current liabilities	5.1	$ 4.9
Long-term debt, less current portion (Note 9)	0.0				$ 380.0
Other long-term liabilities	4.2				12.9
Total partners’ capital	2,763.4				5,412.8
Total liabilities and partners’ capital	$ 2,772.7				$ 5,810.6