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, 2019	Dec. 31, 2018	Dec. 31, 2017	Jan. 01, 2019	Jul. 01, 2018	Jan. 01, 2018
Summary Of Significant Accounting Policies [Line Items]
Increase (decrease) in restricted cash			$ (16.3)	$ 16.3
Operating leases			41.5	0.0
Property, plant and equipment, net			2,909.1	2,029.7
Inventory			53.7	64.6
Contribution of Property	$ 69.4
Net proceeds from sale of assets			0.8	79.5	$ 225.2
Debt Issuance Costs, Net			29.1	26.4
Property, plant and equipment			$ 3,612.5	2,598.1
Percentage of gross income from qualifying sources required to be subject to federal income tax, minimum			90.00%
Goodwill impairment			$ 0.0	0.0	38.8
New Accounting Pronouncement or Change in Accounting Principle, Effect of Adoption, Quantification			0.7
Goodwill, Written off Related to Sale of Business Unit			9.0
Liabilities, Current			357.8	332.1
Operating lease right-of-use assets, net			53.8
Accrued expenses and other liabilities			161.7	112.4
Other long-term liabilities			301.6	173.6
West Coast
Summary Of Significant Accounting Policies [Line Items]
Impairment of intangible assets				0.8
Goodwill impairment					2.4
Natural Gas Liquids
Summary Of Significant Accounting Policies [Line Items]
Inventory			53.2	64.2
CMLP
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, net			3,067.5	2,202.3
Inventory			53.7	64.6
Net proceeds from sale of assets			0.8	79.5	225.2
Property, plant and equipment			3,942.6	2,928.2
Goodwill impairment			0.0	0.0	$ 38.8
Goodwill, Impaired, Accumulated Impairment Loss			1,399.3
Liabilities, Current			353.9	328.5
Operating lease right-of-use assets, net			53.8
Accrued expenses and other liabilities			160.4	111.3
Other long-term liabilities			295.6	171.0
Crestwood Equity Partners LP
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, net			2,909.1	2,029.7
Property, plant and equipment			3,612.5	2,598.1
Goodwill, Impaired, Accumulated Impairment Loss			1,656.5
Accrued expenses and other liabilities			161.7	$ 112.4
Crestwood Permian Basin Holdings LLC
Summary Of Significant Accounting Policies [Line Items]
Guarantee to third party amount			$ 10.0
Equity method ownership percentage			50.00%
Crestwood Permian Basin Holdings LLC | Crestwood Equity Partners LP
Summary Of Significant Accounting Policies [Line Items]
Equity method ownership percentage					50.00%
Stagecoach Gas Services LLC
Summary Of Significant Accounting Policies [Line Items]
Equity method ownership percentage			50.00%				50.00%
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%
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%
Accounting Standards Update 2014-09
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, net								$ 87.6
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
Operating Leases [Member]
Summary Of Significant Accounting Policies [Line Items]
Operating leases			41.5
Operating lease right-of-use assets, net			53.8
Accrued expenses and other liabilities			18.1
Operating Leases [Member] | Accounting Standards Update 2016-02
Summary Of Significant Accounting Policies [Line Items]
Operating leases						$ 48.9
Operating lease right-of-use assets, net						67.5
Accrued expenses and other liabilities						18.6
Finance Lease [Member]
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment, net			9.5
Property, plant and equipment			14.9
Accrued expenses and other liabilities			3.2
Other long-term liabilities			$ 5.2
Finance Lease [Member] | Accounting Standards Update 2016-02
Summary Of Significant Accounting Policies [Line Items]
Property, plant and equipment						1.6
Accrued expenses and other liabilities						0.3
Other long-term liabilities						$ 1.3