Certain Balance Sheet Information (Accrued Expenses and Other Liabilities) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Accrued Expenses and Other Liabilities [Line Items]
Contract Liabilities (Non-current)	$ 151.3	$ 144.7
Accrued expenses	29.7	61.6
Accrued property taxes	4.6	6.1
Tax payable	0.4	0.3
Interest payable	52.0	25.6
Accrued additions to property, plant and equipment	21.7	38.0
Business Combination, Contingent Consideration, Liability, Current	19.0	0.0
Operating Lease, Liability, Current	18.6	18.1
Capital leases		3.2
Finance Lease, Liability, Current	3.3
Deferred Revenue	9.0	8.8
Total accrued expenses and other liabilities	158.3	161.7
Business Combination, Contingent Consideration, Liability, Noncurrent	38.0	57.0
Long-term operating lease liabilities	36.8	41.5
Asset Retirement Obligations, Noncurrent	33.8	33.3
Other long-term liabilities	280.0	301.6
Crestwood Midstream Partners LP
Accrued Expenses and Other Liabilities [Line Items]
Accrued expenses	28.3	60.3
Accrued property taxes	4.6	6.1
Tax payable	0.4	0.3
Interest payable	52.0	25.6
Accrued additions to property, plant and equipment	21.7	38.0
Business Combination, Contingent Consideration, Liability, Current	19.0	0.0
Operating Lease, Liability, Current	18.6	18.1
Capital leases		3.2
Finance Lease, Liability, Current	3.3
Deferred Revenue	9.0	8.8
Total accrued expenses and other liabilities	156.9	160.4
Other long-term liabilities	278.4	295.6
Other Noncurrent Liabilities [Member]
Accrued Expenses and Other Liabilities [Line Items]
Other long-term liabilities	20.1	25.1
Other Noncurrent Liabilities [Member] | Crestwood Midstream Partners LP
Accrued Expenses and Other Liabilities [Line Items]
Other long-term liabilities	$ 18.5	$ 19.1