Basis of Presentation and Summary of Significant Accounting Policies (Narrative) (Details) - USD ($) $ in Millions		1 Months Ended	12 Months Ended
	Jun. 21, 2017	Oct. 31, 2018	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 01, 2019	Jan. 01, 2018
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, net			$ 2,029.7	$ 1,820.8
Deferred Revenue				0.6
Increase (Decrease) in Restricted Cash			16.3
Inventory			64.6	68.4
Contribution of Property	$ 69.0
Net proceeds from sale of assets			79.5	225.2	$ 972.7
Debt Issuance Costs, Net			26.4	28.4
Property, plant and equipment			$ 2,598.1	2,285.2
Percentage of gross income from qualifying sources required to be subject to federal income tax, minimum			90.00%
Goodwill impairment			$ 0.0	38.8	162.6
Goodwill, Written off Related to Sale of Business Unit			9.0
Liabilities, Current			332.1	505.1
West Coast
Summary Of Significant Accounting Policies [Line Items]
Impairment of intangible assets				0.8
Goodwill impairment				2.4	0.0
Marcellus
Summary Of Significant Accounting Policies [Line Items]
Goodwill impairment				0.0	8.6
Trucking
Summary Of Significant Accounting Policies [Line Items]
Impairment of intangible assets					31.4
Goodwill impairment				0.0	29.5
Natural Gas Liquids
Summary Of Significant Accounting Policies [Line Items]
Inventory			64.2	67.9
CMLP
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, net			2,202.3	2,007.5
Inventory			64.6	68.4
Net proceeds from sale of assets			79.5	225.2	972.7
Property, plant and equipment			2,928.2	2,615.3
Deferred revenue			12.0	0.6
Goodwill impairment			0.0	38.8	162.6
Goodwill, Impaired, Accumulated Impairment Loss			1,399.3
Liabilities, Current			328.5	501.3
Crestwood Equity Partners LP
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, net			2,029.7	1,820.8
Property, plant and equipment			2,598.1	2,285.2
Deferred revenue			12.0	0.6
Goodwill impairment				$ 38.8	162.6
Goodwill, Impaired, Accumulated Impairment Loss			$ 1,656.5
Stagecoach Gas Services LLC
Summary Of Significant Accounting Policies [Line Items]
Net proceeds from sale of assets					3.0
Equity method ownership percentage			50.00%
Stagecoach Gas Services LLC | CEGP
Summary Of Significant Accounting Policies [Line Items]
Net proceeds from sale of assets					$ 975.0
Stagecoach Gas Services LLC | CMLP
Summary Of Significant Accounting Policies [Line Items]
Equity method ownership percentage					50.00%
Measurement Input, Discount Rate
Summary Of Significant Accounting Policies [Line Items]
Fair Value Inputs				12.00%	10.00%
Measurement Input, Discount Rate | Minimum
Summary Of Significant Accounting Policies [Line Items]
Fair Value Inputs				10.00%
Measurement Input, Discount Rate | Maximum
Summary Of Significant Accounting Policies [Line Items]
Fair Value Inputs				12.00%	19.00%
Accounting Standards Update 2014-09
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, net							$ 87.6
Deferred Revenue							$ 69.1
Accounting Standards Update 2016-02
Summary Of Significant Accounting Policies [Line Items]
Assets, Noncurrent						$ 69.0
Liabilities, Current						19.0
Liabilities, Noncurrent						$ 50.0
Marketing Supply and Logistics
Summary Of Significant Accounting Policies [Line Items]
Goodwill impairment				$ 38.8	$ 109.1
Marketing Supply and Logistics | CMLP
Summary Of Significant Accounting Policies [Line Items]
Goodwill impairment				38.8	$ 109.1
West Coast | Marketing Supply and Logistics
Summary Of Significant Accounting Policies [Line Items]
Property, Plant and Equipment, Gross, Period Increase (Decrease)		$ (61.8)
Disposal Group, Including Discontinued Operation, Consideration		$ 70.5
Gain (Loss) on Sale of Assets and Asset Impairment Charges			$ 26.9	$ 81.4