Long-Term Debt (Components Of Long-Term Debt) (Detail) - USD ($) $ in Millions	Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Debt Instrument [Line Items]
Senior notes		$ 0.0	$ 350.0
Premium on Crestwood Midstream 2019 Senior Notes		0.0	1.0
Deferred Finance Costs, Net	$ 39.2	40.9
Total Crestwood Equity debt	2,531.7	2,502.7	2,015.3
Other	0.0	0.2	0.8
Less: current portion	0.9	0.9	0.8
Total long-term debt, less current portion	2,530.8	2,501.8	2,014.5
Scenario, Previously Reported
Debt Instrument [Line Items]
Total Crestwood Equity debt		2,543.6
Total long-term debt, less current portion		2,542.7
Senior Notes, 2020
Debt Instrument [Line Items]
Senior notes	503.2	503.3	504.0
Senior Notes, 2022
Debt Instrument [Line Items]
Senior notes	600.0	600.0	600.0
Senior Notes, 2023
Debt Instrument [Line Items]
Senior notes	700.0	700.0	0.0
Senior Notes \| Senior Notes, 2020
Debt Instrument [Line Items]
Senior notes	500.0	500.0	500.0
Senior Notes \| Senior Notes, 2022
Debt Instrument [Line Items]
Senior notes	600.0	600.0	600.0
Senior Notes \| Senior Notes, 2023
Debt Instrument [Line Items]
Senior notes	700.0	700.0	0.0
Fair value adjustment of 2020 Senior Notes \| Senior Notes, 2020
Debt Instrument [Line Items]
Fair value adjustment	3.2	3.3	4.0
Other
Debt Instrument [Line Items]
Other	4.9	5.3	5.3
CEQP Senior Notes \| CEQP Senior Notes
Debt Instrument [Line Items]
Senior notes		0.0	11.4
Crestwood Equity Partners LP
Debt Instrument [Line Items]
Senior notes		0.0	11.4
Total Crestwood Equity debt	2,531.7	2,502.9	2,396.5
Less: current portion	0.9	1.1	3.7
Total long-term debt, less current portion	2,530.8	2,501.8	2,392.8
Crestwood Equity Partners LP \| Scenario, Previously Reported
Debt Instrument [Line Items]
Total Crestwood Equity debt		2,543.8
Total long-term debt, less current portion		2,542.7
Revolving Credit Facility \| Crestwood Midstream Revolver
Debt Instrument [Line Items]
Credit agreement outstanding carrying value	$ 762.8	735.0	555.0
Revolving Credit Facility \| Line of Credit \| CEQP Credit Facility
Debt Instrument [Line Items]
Credit agreement outstanding carrying value		$ 0.0	$ 369.0

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The amount of debt discount (net of debt premium) that was originally recognized at the issuance of the instrument that has yet to be amortized.

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Represents the aggregate of total long-term debt, including current maturities and short-term debt.

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The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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Amount of long-term debt, after unamortized discount or premium, scheduled to be repaid within one year or the normal operating cycle, if longer. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Including both current and noncurrent portions, carrying amount as of the balance sheet date of other forms of debt not elsewhere specified in the taxonomy with initial maturities beyond one year or beyond the normal operating cycle, if longer.

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