Certain Balance Sheet Information (Accrued Expenses and Other Liabilities) (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Accrued Expenses and Other Liabilities [Line Items]
Accrued expenses	$ 40.6	$ 46.9
Accrued property taxes	6.3	4.2
Accrued product purchases payable	0.7	4.9
Tax payable	0.0	1.2
Interest payable	39.7	22.8
Accrued additions to property, plant and equipment	16.6	1.7
Capital leases	1.1	1.3
Deferred revenue	7.5	7.5
Total accrued expenses and other liabilities	112.5	90.5
Crestwood Midstream Partners LP
Accrued Expenses and Other Liabilities [Line Items]
Accrued expenses	39.9	45.5
Accrued property taxes	6.3	4.2
Accrued product purchases payable	0.7	4.9
Tax payable	0.0	0.0
Interest payable	39.7	22.8
Accrued additions to property, plant and equipment	16.6	1.7
Capital leases	1.1	1.3
Deferred revenue	7.5	7.5
Total accrued expenses and other liabilities	$ 111.8	$ 87.9