Certain Balance Sheet Information (Accrued Expenses and Other Liabilities) (Details) - USD ($) $ in Millions	1 Months Ended	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Accrued Expenses and Other Liabilities [Line Items]
Net proceeds from sale of assets	$ 945.0	$ 1.0	$ 942.0
Payments to acquire equity method investments		18.5	5.5
Accrued expenses		39.0		$ 46.9
Accrued property taxes		6.6		4.2
Accrued product purchases payable		0.2		4.9
Tax payable		0.3		1.2
Interest payable		21.6		22.8
Accrued additions to property, plant and equipment		9.0		1.7
Capital leases		1.1		1.3
Deferred revenue		6.7		7.5
Total accrued expenses and other liabilities		84.5		90.5
Crestwood Midstream Partners LP
Accrued Expenses and Other Liabilities [Line Items]
Net proceeds from sale of assets		1.0	942.0
Payments to acquire equity method investments		18.5	$ 5.5
Accrued expenses		38.1		45.5
Accrued property taxes		6.6		4.2
Accrued product purchases payable		0.2		4.9
Tax payable		0.0		0.0
Interest payable		21.6		22.8
Accrued additions to property, plant and equipment		9.0		1.7
Capital leases		1.1		1.3
Deferred revenue		6.7		7.5
Total accrued expenses and other liabilities		$ 83.3		$ 87.9