Crestwood Equity Partners (CEQP+) 10-Q 7 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015	4-May-15
Document Information [Line Items]
Entity Registrant Name	Crestwood Midstream Partners LP
Trading Symbol	CMLP
Entity Central Index Key	1304464
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Document Type	10-Q
Document Period End Date	31-Mar-15
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Amendment Flag	FALSE
Limited Partner Units
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		188,291,848
Preferred Units, Class A
Document Information [Line Items]
Entity Common Stock, Shares Outstanding		18,332,195

CONSOLIDATED_BALANCE_SHEETS

CONSOLIDATED BALANCE SHEETS (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Current assets:
Cash	$66.80	$4.60
Accounts receivable	192.6	241.8
Inventory	9.2	8
Prepaid expenses and other current assets	23.6	18.7
Total current assets	292.2	273.1
Property, plant and equipment (Note 4)	3,897	3,883.50
Less: accumulated depreciation and depletion	391.6	365.4
Property, plant and equipment, net	3,505.40	3,518.10
Intangible assets:
Intangible assets (Note 4)	1,020.20	1,013.20
Less: accumulated amortization	155.5	137
Intangible assets, net	864.7	876.2
Goodwill	1,632.60	1,632.60
Investment in unconsolidated affiliates (Note 5)	316.6	295.1
Other assets	1.2	1.4
Total assets	6,612.70	6,596.50
Current liabilities:
Accounts payable	128.6	132.4
Accrued expenses and other liabilities (Note 4)	57	122
Current portion of long-term debt (Note 6)	36.1	0.7
Total current liabilities	221.7	255.1
Long-term debt, less current portion (Note 6)	2,121.70	2,012.80
Other long-term liabilities	31.5	31.2
Commitments and contingencies (Note 10)
Partners’ capital (Note 8):
Class A preferred units (18,332,195 and 17,917,870 units issued and outstanding at March 31, 2015 and December 31, 2014)	456.9	447.7
Partners’ capital (188,304,921 and 187,965,105 limited partner units issued and outstanding at March 31, 2015 and December 31, 2014)	3,603.60	3,678
Total Crestwood Midstream Partners LP partners’ capital	4,060.50	4,125.70
Interest of non-controlling partners in subsidiary	177.3	171.7
Total partners’ capital	4,237.80	4,297.40
Total liabilities and partners’ capital	$6,612.70	$6,596.50

CONSOLIDATED_BALANCE_SHEETS_Pa

CONSOLIDATED BALANCE SHEETS (Parenthetical)	Mar. 31, 2015	Dec. 31, 2014
Statement of Financial Position [Abstract]
Preferred units, issued	18,332,195	17,917,870
Preferred units, outstanding	18,332,195	17,917,870
Common units, issued	188,304,921	187,965,105
Common units, outstanding	188,304,921	187,965,105

CONSOLIDATED_STATEMENTS_OF_OPE

CONSOLIDATED STATEMENTS OF OPERATIONS (USD $)	3 Months Ended
In Millions, except Share data in Thousands, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Revenues:
Gathering and processing	$77.30	$78.60
Storage and transportation	45.7	44.3
NGL and crude services	327.5	409.9
Related party (Note 11)	4.6	4.2
Revenues	455.1	537
Costs of product/services sold:
Gathering and processing	4.4	7.7
Storage and transportation	3.3	3.2
NGL and crude services	270.6	376.2
Related party (Note 11)	8.3	11
Costs of product/services sold	286.6	398.1
Expenses:
Operations and maintenance	35.1	28
General and administrative	24.2	24.1
Depreciation, amortization and accretion	59.9	50.8
Total Expenses	119.2	102.9
Other operating income (expense):
Gain (loss) on long-lived assets, net	-0.8	0.5
Loss on contingent consideration	0	-2.1
Operating income	48.5	34.4
Earnings (loss) from unconsolidated affiliates, net	3.4	-0.1
Interest and debt expense, net	-29.9	-28.1
Income before income taxes	22	6.2
Provision for income taxes	0.3	0.7
Net income	21.7	5.5
Net income attributable to non-controlling partners	-5.6	-3.1
Net income attributable to Crestwood Midstream Partners LP	16.1	2.4
Net income attributable to Class A preferred units	-9.2	0
Net income attributable to partners	6.9	2.4
Partners’ interest information:
General partner's interest in net income	7.5	7.5
Limited partners’ interest in net income (loss)	($0.60)	($5.10)
Net income (loss) per limited partner unit:
Basic (usd per unit)	$0	($0.03)
Diluted (usd per unit)	$0	($0.03)
Weighted-average limited partners’ units outstanding:
Basic (units)	188,290	187,840
Diluted (units)	188,290	187,840

CONSOLIDATED_STATEMENT_OF_PART

CONSOLIDATED STATEMENT OF PARTNERS' CAPITAL (USD $)	Total	Preferred Partner	Limited Partner	Non Controlling Partners	Partners' Capital
In Millions, unless otherwise specified
Beginning Balance at Dec. 31, 2014	$4,125.70	$447.70	$3,678	$171.70	$4,297.40
Increase (Decrease) in Partners' Capital [Roll Forward]
Distributions to general partner	10.5	0	-10.5	0	-10.5
Distributions to limited partners		0	-74.3	0	-74.3
Unit-based compensation charges		0	5.2	0	5.2
Taxes paid for unit-based compensation vesting		0	-1.7	0	-1.7
Net income	21.7	9.2	6.9	5.6	21.7
Ending Balance at Mar. 31, 2015	$4,060.50	$456.90	$3,603.60	$177.30	$4,237.80

CONSOLIDATED_STATEMENTS_OF_CAS

CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Operating activities
Net income	$21.70	$5.50
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and accretion	59.9	50.8
Amortization of debt-related deferred costs and premiums	1.9	1.8
Unit-based compensation charges	5.2	4.6
(Gain) loss on long-lived assets	0.8	-0.5
Loss on contingent consideration	0	2.1
(Earnings) loss from unconsolidated affiliates, net	-3.4	0.1
Deferred income taxes	0.1	0.5
Other	0	0.2
Changes in operating assets and liabilities, net of effects from acquisitions	-9.2	2.6
Net cash provided by operating activities	77	67.7
Investing activities
Acquisitions, net of cash acquired (Note 3)	0	-12.1
Purchases of property, plant and equipment	-43.3	-77.3
Investment in unconsolidated affiliates	-17.9	-19.8
Proceeds from sale of assets	0.3	0
Net cash used in investing activities	-60.9	-109.2
Financing activities
Proceeds from the issuance of long-term debt	1,114.60	306
Principal payments on long-term debt	-970	-188.8
Payments on capital leases	-0.7	-1.1
Payments for debt-related deferred costs	-11.1	0
Distributions to limited partners	-74.3	-74.1
Distributions to general partner	-10.5	-10.5
Net proceeds from issuance of preferred equity of subsidiary	0	12.3
Taxes paid for unit-based compensation vesting	-1.7	0
Other	-0.2	0
Net cash provided by financing activities	46.1	43.8
Net change in cash	62.2	2.3
Cash at beginning of period	4.6
Cash at end of period	66.8	5
Supplemental schedule of non-cash investing and financing activities
Net change to property, plant and equipment through accounts payable and accrued expenses	($9.10)	($3.40)

Business_Description

Business Description	3 Months Ended
	Mar. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Business Description	Business Description
	Crestwood Midstream Partners LP (the Company or Crestwood) is a publicly-traded (NYSE: CMLP) Delaware limited partnership that provides midstream solutions to customers in the crude oil, natural gas liquids (NGLs) and natural gas sectors of the energy industry. We are engaged primarily in the gathering, processing, storage and transportation of natural gas and NGLs, the marketing of NGLs, and the gathering, storage and transportation of crude oil.
	Crestwood Equity Partners LP (CEQP) indirectly owns a non-economic general partnership interest in us and 100% of our incentive distribution rights (IDRs), which entitle CEQP to receive 50% of all distributions paid to our common unit holders in excess of our initial quarterly distribution of $0.37 per common unit. As of March 31, 2015, CEQP directly owns approximately 4% of our common limited partnership units. CEQP is indirectly owned by Crestwood Holdings LLC (Crestwood Holdings), which owns approximately 11% of our common units as of March 31, 2015. Crestwood Holdings is substantially owned and controlled by First Reserve Management, L.P. (First Reserve).
	Our financial statements reflect three operating and reporting segments, including:
	•	Gathering and Processing: our gathering and processing (G&P) operations provide natural gas gathering, processing, treating, compression, transportation services and sales of natural gas and the delivery of NGLs to producers in unconventional shale plays and tight-gas plays in West Virginia, Wyoming, Texas, Arkansas, New Mexico and Louisiana. This segment primarily includes our rich gas gathering systems and processing plants in the Marcellus, Powder River Basin (PRB) Niobrara, Barnett, and Permian Shale plays, and our dry gas gathering systems in the Barnett, Fayetteville, and Haynesville Shale plays;
	•	Storage and Transportation: our storage and transportation operations provide regulated natural gas storage and transportation services to producers, utilities and other customers. This segment primarily includes our natural gas storage facilities (Stagecoach, Thomas Corners, Steuben and Seneca Lake) and our natural gas transmission facilities (the North-South Facilities, the MARC I Pipeline and the East Pipeline) in New York and Pennsylvania; and
	•	NGL and Crude Services: our NGL and crude services operations provide NGLs and crude oil gathering, storage, marketing and transportation services to producers, refiners, marketers and other customers in or near unconventional shale plays in North Dakota and New York. This segment primarily includes our integrated Bakken crude oil footprint in North Dakota, which consists of (i) the COLT Hub, a crude oil rail loading and storage terminal, (ii) the Arrow crude oil, natural gas and water gathering systems, and (iii) our fleet of over-the-road crude and produced water transportation assets. This segment also includes our solution-mining and salt production company (US Salt) and Bath storage facility in New York.
	On May 5, 2015, CEQP, CMLP and certain of its affiliates entered into a definitive agreement under which CMLP has agreed to merge with a wholly-owned subsidiary of CEQP, with CMLP surviving as a wholly-owned subsidiary of CEQP.  As part of the merger consideration, CMLP’s unitholders will become unitholders of CEQP in a tax free exchange, with CMLP’s common unitholders receiving 2.75 common units of CEQP for each common unit of CMLP held upon completion of the merger.  CMLP’s IDRs will also be eliminated upon completion of the merger and CMLP’s common units will cease to be listed on the NYSE.  CMLP expects to complete the merger in the third quarter of 2015, subject to the approval of Crestwood Midstream's unitholders and customary closing conditions.
	Unless otherwise indicated, references in this report to “we,” “us,” “our,” “ours,” “our company,” the “partnership,” the “Company,” “CMLP,” “Crestwood” and similar terms refer to either Crestwood Midstream Partners LP itself or Crestwood Midstream Partners LP and its consolidated subsidiaries, as the context requires.

Basis_of_Presentation_and_Summ

Basis of Presentation and Summary of Significant Accounting Policies	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Basis of Presentation and Summary of Significant Accounting Policies	Basis of Presentation and Summary of Significant Accounting Policies
	Basis of Presentation
	The financial information as of March 31, 2015, and for the three months ended March 31, 2015 and 2014, is unaudited. The consolidated balance sheet as of December 31, 2014, was derived from the audited balance sheet filed in our 2014 Annual Report on Form 10-K. Our consolidated financial statements are prepared in accordance with accounting principles generally accepted in the United States of America (GAAP) and include the accounts of all consolidated subsidiaries after the elimination of all intercompany accounts and transactions. In management’s opinion, all necessary adjustments to fairly present our results of operations, financial position and cash flows for the periods presented have been made and all such adjustments are of a normal and recurring nature. Certain information and footnote disclosures normally included in annual consolidated financial statements prepared in accordance with GAAP have been omitted pursuant to the rules and regulations of the Securities and Exchange Commission (SEC).
	Our consolidated financial statements for the prior period include reclassifications that were made to conform to the current period presentation. Cash inflows of $9.6 million related to reimbursements of capital expenditures from producers have been reclassified from investing activities to changes in operating assets and liabilities, net of effects from acquisitions under operating activities in our consolidated statements of cash flows for the three months ended March 31, 2014 to conform with the current period presentation. The reclassification was not significant to our previously reported consolidated financial statements.
	The accompanying consolidated financial statements should be read in conjunction with our 2014 Annual Report on Form 10-K filed with the SEC on February 27, 2015.
	Significant Accounting Policies
	There were no material changes in our significant accounting policies from those described in our 2014 Annual Report on Form 10-K.
	New Accounting Pronouncements Issued But Not Yet Adopted
	As of March 31, 2015, the following accounting standards had not yet been adopted by us.
	In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update 2014-09, Revenue from Contracts with Customers, which outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes current revenue recognition guidance. We expect to adopt the provisions of this standard effective January 1, 2017 and are currently evaluating the impact that this standard will have on our consolidated financial statements. In April 2015, the FASB proposed deferring the effective date of this standard by one year.
	In February 2015, the FASB issued Accounting Standards Update 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis, which provides additional guidance on the consolidation of limited partnerships and on the evaluation of variable interest entities. We expect to adopt the provisions of this standard effective January 1, 2016 and are currently evaluating the impact, if any, that this standard may have on our consolidated financial statements.
	In April 2015, the FASB issued Accounting Standards Update 2015-03, Interest - Imputation of Interest (Subtopic 835-30), which requires deferred debt issuance costs to be classified as a reduction of the debt liability rather than as an asset in the balance sheet. We expect to adopt the provisions of this standard effective January 1, 2016, and do not currently anticipate it will have a significant impact on our consolidated financial statements.

Acquisitions_and_Divestitures

Acquisitions and Divestitures	3 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
Acquisitions	Acquisition
	2014 Acquisition
	Crude Transportation Acquisition (Bakken)
	Red Rock. On March 21, 2014, we purchased substantially all of the trucking operations of Red Rock Transportation Inc. (Red Rock) for approximately $13.8 million, comprised of $12.1 million paid at closing plus deferred payments of $1.8 million. These operations are located in Watford City, North Dakota and provide crude oil and produced water hauling services to the oilfields of western North Dakota and eastern Montana. The acquired assets include a fleet of approximately 56 trailer tanks, 22 double bottom body tanks and 44 tractors with 28,000 barrels per day of transportation capacity. In the first quarter of 2014, we finalized the purchase price and allocated approximately $10.6 million of the purchase price to property, plant and equipment and intangible assets and approximately $3.2 million to goodwill. Goodwill recognized relates primarily to anticipated operating synergies between the assets acquired and our existing assets. These assets are included in our NGL and crude services segment.
	This acquisition was not material to our NGL and crude services segment's results of operations for the three months ended March 31, 2014. In addition, transaction costs related to this acquisition was not material for the three months ended March 31, 2014.

Certain_Balance_Sheet_Informat

Certain Balance Sheet Information	3 Months Ended
	Mar. 31, 2015
Balance Sheet Related Disclosures [Abstract]
Certain Balance Sheet Information	Certain Balance Sheet Information
	Property, Plant and Equipment
	Property, plant and equipment consisted of the following at March 31, 2015 and December 31, 2014 (in millions):
		March 31,		December 31,
		2015		2014
	Gathering systems and pipelines	1,281.20		1,276.60
	Facilities and equipment	1,458.00		1,468.80
	Buildings, land, rights-of-way, storage contracts and easements	808.1		806.4
	Vehicles	14.1		13.6
	Construction in process	171.2		153.7
	Base gas	37.5		37.5
	Salt deposits	120.5		120.5
	Office furniture and fixtures	6.4		6.4
		3,897.00		3,883.50
	Less: accumulated depreciation and depletion	391.6		365.4
	Total property, plant and equipment, net	$	3,505.40	$	3,518.10
	Capital Leases. We have a treating facility and certain auto leases which are accounted for as capital leases. Our treating facility lease is reflected in facilities and equipment in the above table. We had capital lease assets of $2.6 million and $2.8 million included in property, plant and equipment, net at March 31, 2015 and December 31, 2014.
	Intangible Assets
	Intangible assets consisted of the following at March 31, 2015 and December 31, 2014 (in millions):
		March 31,		December 31,
		2015		2014
	Customer accounts	$	483.2	$	483.2
	Covenants not to compete	5.6		5.6
	Gas gathering, compression and processing contracts	427.3		431.4
	Acquired storage contracts	29		29
	Trademarks	9.7		9.7
	Deferred financing costs	65.4		54.3
		1,020.20		1,013.20
	Less: accumulated amortization	155.5		137
	Total intangible assets, net	$	864.7	$	876.2
	Accrued Expenses and Other Liabilities
	Accrued expenses and other liabilities consisted of the following at March 31, 2015 and December 31, 2014 (in millions):
		March 31,		December 31, 2014
		2015
	Accrued expenses	$	17.9	$	23.7
	Accrued property taxes	3.9		2.1
	Accrued product purchases payable	0.4		0.7
	Tax payable	—		0.4
	Interest payable	13.5		22
	Accrued additions to property, plant and equipment	9.1		20
	Commitments and contingent liabilities (Note 10)	—		40
	Capital leases	0.9		1.3
	Deferred revenue	11.3		11.6
	Other	—		0.2
	Total accrued expenses and other liabilities	$	57	$	122

Investments_in_Unconsolidated_

Investments in Unconsolidated Affiliates	3 Months Ended
	Mar. 31, 2015
Equity Method Investments and Joint Ventures [Abstract]
Investments in Unconsolidated Affiliates	Investments in Unconsolidated Affiliates
	Net Investment and Earnings (Loss)
	Our net investments in and earnings (loss) from our unconsolidated affiliates are as follows (in millions, unless otherwise stated):
			Ownership Percentage			Investment				Earnings (Loss) from Unconsolidated Affiliates
			March 31,			March 31,		December 31,		Three Months Ended March 31,
			2015			2015		2014		2015		2014
	Jackalope Gas Gathering Services, L.L.C.(1)		50	%	(4)	$	244.2	$	232.9	$	2.5	$	0.3
	Tres Palacios Holdings LLC(2)		50.01	%		42.8		36		0.9		—
	Powder River Basin Industrial Complex, LLC(3)		50.01	%		29.6		26.2		—		(0.4		)
	Total					$	316.6	$	295.1	$	3.4	$	(0.1	)
	-1	As of March 31, 2015, our investment balance exceeded our equity in the underlying net assets of Jackalope Gas Gathering Services, L.L.C. (Jackalope)by approximately $52.9 million. We amortize and generally assess the recoverability of this amount over 20 years, which represents the life of Jackalope’s gathering agreement with Chesapeake Energy Corporation and RKI Exploration and Production, LLC, and reflect the amortization as a reduction of our earnings from unconsolidated affiliates. For the three months ended March 31, 2015 and 2014, we recorded amortization of approximately $0.8 million. Our Jackalope investment is included in our gathering and processing segment.
	-2	In December 2014, one of our consolidated subsidiaries and an affiliate of Brookfield Infrastructure Group (Brookfield) formed the Tres Palacios Holdings LLC (Tres Holdings) joint venture. For more information on our joint venture, see our 2014 Annual Report on Form 10-K filed with the SEC. As of March 31, 2015, our equity in the underlying net assets exceeded our investment balance in Tres Holdings by approximately $30.0 million. We amortize and generally assess the recoverability of this amount over the life of the Tres Palacios Gas Storage LLC (Tres Palacios) sublease agreement, and reflect the amortization as an increase of our earnings from unconsolidated affiliates. For the three months ended March 31, 2015, we recorded amortization of approximately $0.3 million. Our Tres Holdings investment is included in our storage and transportation segment.
	-3	As of March 31, 2015, our investment balance approximated our equity in the underlying net assets of Powder River Basin Industrial Complex, LLC (PRBIC). Our PRBIC investment is included in our NGL and crude services segment.
	-4	Excludes non-controlling interests related to our investment in Jackalope. See Note 8 for a further discussion of our non-controlling interest related to our investment in Jackalope.
	Distributions and Contributions
	Jackalope. Jackalope is required, within 30 days following the end of each quarter, to make quarterly distributions of its available cash to its members based on their respective ownership percentage. During the three months ended March 31, 2015 and 2014, Jackalope did not make any distributions to its members. In April 2015, we received a cash distribution of approximately $4.5 million from Jackalope. During the three months ended March 31, 2015 and 2014, we contributed approximately $8.8 million and $17.3 million to Jackalope.
	Tres Holdings. Tres Holdings is required, within 30 days following the end of each quarter, to make quarterly distributions of its available cash (as defined in its limited liability company agreement) to its members based on their respective ownership percentage. In April 2015, we received a cash distribution of approximately $2.1 million from Tres Holdings. During the three months ended March 31, 2015, we contributed approximately $5.7 million to Tres Holdings.
	PRBIC. PRBIC is required to make quarterly distributions of its available cash to its members based on their respective ownership percentage. During the three months ended March 31, 2015, we received a cash distribution of approximately $0.3 million from PRBIC as a return of capital. During the three months ended March 31, 2014, PRBIC did not make any distributions to its members. In addition, during the three months ended March 31, 2015 and 2014, we contributed approximately $3.7 million and $2.5 million to PRBIC.

Financial_Instruments

Financial Instruments	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Financial Instruments	Financial Instruments
	Fair Value
	We separate the fair values of our financial instruments into three levels (Levels 1, 2 and 3) based on our assessment of the availability of observable market data and the significance of non-observable data used to determine fair value. Our assessment and classification of an instrument within a level can change over time based on the maturity or liquidity of the instruments and would be reflected at the end of the period in which the change occurs. At March 31, 2015 and December 31, 2014, there were no changes to the inputs and valuation techniques used to measure fair value, the types of instruments, or the levels in which they are classified.
	We enter into daily and short-term forward crude purchase and sale agreements in our NGL and crude services segment related to available capacity on our crude contracts and facilities associated with our operations located in the Bakken and PRB Niobrara Shale plays. As of March 31, 2015, our outstanding positions and the related impact to our consolidated statement of operations associated with our risk management activities were not material. As of March 31, 2014, we did not have any risk management activities.
	As of March 31, 2015 and December 31, 2014, the carrying amounts of cash, accounts receivable and accounts payable represent fair value based on the short-term nature of these instruments. The fair value of the amount outstanding under our credit facility approximates its carrying amount as of March 31, 2015 and December 31, 2014 due primarily to the variable nature of the interest rate of the instrument, which is considered a Level 2 fair value measurement.
	We estimate the fair value of our senior notes primarily based on quoted market prices for the same or similar issuances (representing a Level 2 fair value measurement). The following table reflects the carrying value and fair value of our senior notes (in millions):
		March 31, 2015				December 31, 2014
		Carrying Amount		Fair		Carrying Amount		Fair
				Value				Value
	2019 Senior Notes	$	350.9	$	363.6	$	351	$	360.5
	2020 Senior Notes	$	503.8	$	500.3	$	504	$	481.6
	2022 Senior Notes	$	600	$	607.5	$	600	$	568.5
	2023 Senior Notes	$	700	$	710.5	$	—	$	—
	Debt
	Long-term debt consisted of the following at March 31, 2015 and December 31, 2014 (in millions):
		March 31,		December 31,
		2015		2014
	Credit Facility	$	—	$	555
	2019 Senior Notes	350		350
	Premium on 2019 Senior Notes	0.9		1
	2020 Senior Notes	500		500
	Fair value adjustment of 2020 Senior Notes	3.8		4
	2022 Senior Notes	600		600
	2023 Senior Notes	700		—
	Other	3.1		3.5
	Total debt	2,157.80		2,013.50
	Less: current portion	36.1		0.7
	Total long-term debt	$	2,121.70	$	2,012.80
	Credit Facility
	We have a five-year $1.0 billion senior secured revolving credit facility (the Credit Facility), which expires in October 2018 and is available to fund acquisitions, working capital and internal growth projects and for general partnership purposes. The Credit Facility includes a sub-limit up to $25 million for same-day swing line advances and a sub-limit up to $250 million for letters of credit. Subject to limited exception, the Credit Facility is secured by substantially all of the equity interests and assets of our subsidiaries except for Crestwood Niobrara LLC (Crestwood Niobrara), PRBIC and Tres Holdings and their respective subsidiaries.
	At March 31, 2015, we had $429.1 million of available capacity under the Credit Facility considering the most restrictive debt covenants in our credit agreement. In March 2015, we utilized proceeds from our 2023 Senior Notes offerings to pay down the outstanding balance on our Credit Facility as discussed below. At March 31, 2015 and December 31, 2014, our outstanding standby letters of credit were $5.6 million and $15.1 million. Borrowings under our Credit Facility accrue interest at prime or LIBOR-based rates plus applicable spreads, which resulted in interest rates between 2.66% and 4.75% at December 31, 2014. The weighted-average interest rate as of December 31, 2014 was 2.86%.
	We are required under our credit agreement to maintain a net debt to consolidated EBITDA ratio (as defined in our credit agreement) of not more than 5.00 to 1.0 (or, if applicable, 5.50 to 1.0 during certain periods immediately following a material acquisition by us) and a consolidated EBITDA to consolidated interest expense ratio (as defined in our credit agreement) of not less than 2.50 to 1.0. As a result of our election to increase the permitted net debt to consolidated EBITDA ratio in conjunction with our 50.01% acquisition of Tres Palacios, the net debt to consolidated EBITDA ratio required by our credit agreement is 5.50 for a 270-day period commencing December 3, 2014. At March 31, 2015, our net debt to consolidated EBITDA was approximately 4.58 to 1.0 and consolidated EBITDA to consolidated interest expense was approximately 4.15 to 1.0.
	Senior Notes
	As of March 31, 2015, we had four series of senior unsecured notes outstanding, including (i) $350 million in aggregate principal amount of 7.75% Senior Notes due 2019 (the 2019 Senior Notes), (ii) $500 million in aggregate principal amount of 6.0% Senior Notes due 2020 (the 2020 Senior Notes), (iii) $600 million in aggregate principal amount of 6.125% Senior Notes due 2022 (the 2022 Senior Notes), and (iv) $700 million in aggregate principal amount of 6.25% Senior Notes due 2023 (the 2023 Senior Notes and together with the 2019 Senior Notes, the 2020 Senior Notes and the 2022 Senior Notes, our Senior Notes). Our Senior Notes are guaranteed on a senior unsecured basis by all of our domestic restricted subsidiaries, subject to certain exceptions.
	In March 2015, we issued $700 million of 6.25% unsecured Senior Notes due 2023 in a private offering. The 2023 Senior Notes will mature on April 1, 2023, and interest is payable semiannually in arrears on April 1 and October 1 of each year, beginning October 1, 2015. The net proceeds from this offering of approximately $688.9 million were used to pay down borrowings under our Credit Facility and for our general partnership purposes.
	On April 8, 2015, we redeemed the 2019 Senior Notes for approximately $364.1 million, including accrued interest of $0.5 million and a call premium of $13.6 million. We utilized approximately $315 million of our Credit Facility to redeem all of the outstanding 2019 Senior Notes.
	At March 31, 2015, we were in compliance with all of our debt covenants applicable to our Credit Facility and our Senior Notes. For additional information regarding our debt covenants, see our 2014 Annual Report on Form 10-K filed with the SEC.
	Other
	For a description of our non-interest bearing obligations due under noncompetition agreements, see our 2014 Annual Report on Form 10-K filed with the SEC.

Earnings_Per_Limited_Partner_U

Earnings Per Limited Partner Unit Earnings Per Limited Partner Unit	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Earnings Per Limited Partner Unit	Earnings Per Limited Partner Unit
	CEQP, through its wholly-owned subsidiaries, owns a non-economic general partner interest in us and 100% of our IDRs. We allocate net income attributable to CMLP to our limited partners after giving effect to the IDRs earned by CEQP and net income attributable to the Class A preferred units.
	Basic earnings per unit are calculated using the two-class method. Diluted earnings per unit are computed using the treasury stock method, which considers the impact to net income attributable to CMLP and limited partner units from the potential issuance of limited partner units as discussed below. The weighted average number of units outstanding is calculated based on the presumption that the number of common units issued by Legacy Inergy to Legacy Crestwood unitholders as part of the Crestwood Merger were outstanding for the entire period prior to Crestwood Merger.
	The tables below show the (i) allocation of net income attributable to CMLP and the (ii) net income attributable to CMLP per limited partner unit based on the number of basic and diluted limited partner units outstanding for the three months ended March 31, 2015 and 2014 (in millions):
	Allocation of Net Income Attributable to CMLP
		Three Months Ended
		March 31,
		2015			2014
	Net income attributable to CMLP	$	16.1		$	2.4
	Class A preferred units’ interest in net income attributable to CMLP	(9.2		)	—
	General partner’s incentive distributions	(7.5		)	(7.5		)
	Limited partners’ interest in net income (loss) attributable to CMLP after incentive distributions	$	(0.6	)	$	(5.1	)
	Earnings Per Limited Partner Unit
		Three Months Ended
		March 31,
		2015			2014
	Limited partners’ interest in net income (loss)	$	(0.6	)	$	(5.1	)
	Weighted-average limited partner units - basic	188.3			187.8
	Effect of diluted units	—			—
	Weighted-average limited partner units - diluted	188.3			187.8
	Basic earnings per unit:
	Net income (loss) per limited partner	$	—		$	(0.03	)
	Diluted earnings per unit:
	Net income (loss) per limited partner	$	—		$	(0.03	)
	We exclude potentially dilutive securities from the determination of diluted earnings per unit (as well as their related income statement impacts) when their impact on net income attributable to CMLP per limited partner unit is anti-dilutive. During the three months ended March 31, 2015, we also excluded a weighted-average of 18,332,193 common units, representing Class A preferred units if converted to common units, from our diluted earnings per unit. During the three months ended March 31, 2015 and 2014, we excluded a weighted-average of 12,325,740 and 4,922,372 common units, representing Crestwood Niobrara's preferred units if converted to common units, from our diluted earnings per unit. See Note 8 for additional information regarding the potential conversion of the preferred units to common units.

Partners_Capital

Partners' Capital	3 Months Ended
	Mar. 31, 2015
Partners' Capital [Abstract]
Partners' Capital	Partners’ Capital
	Class A Preferred Units
	On June 17, 2014, we entered into definitive agreements with a group of investors, including Magnetar Financial, affiliates of GSO Capital Partners LP and GE Energy Financial Services (the Class A Purchasers). Under these agreements, we have agreed to sell to the Class A Purchasers and the Class A Purchasers have agreed to purchase from us up to $500 million of Preferred Units at a fixed price of $25.10 per unit on or before September 30, 2015. During the three months ended March 31, 2015 and through the date of this filing, we did not sell any Preferred Units to the Class A Purchasers under these agreements. For additional information on our Class A Preferred Units, see our 2014 Annual Report on Form 10-K filed with the SEC.
	Equity Distribution Agreement
	We entered into an equity distribution program with certain financial institutions (each, a Manager) under which we are allowed to offer and sell, from time to time through one or more of the Managers, common units having an aggregate offering price of up to $300.0 million. We will pay the Managers an aggregate fee of up to 2.0% of the gross sales price per common unit sold under this at-the-market program. We did not issue any common units under this equity distribution program as of March 31, 2015 and through the date of this filing.
	Distributions
	Our partnership agreement requires us to distribute, within 45 days after the end of each quarter, all available cash (as defined in our partnership agreement) to our common unitholders of record on the applicable record date. The general partner is not entitled to distributions on its non-economic general partner interest.
	Distributions to General Partner
	During the three months ended March 31, 2015 and 2014, we paid cash distributions to our general partner (representing IDRs and distributions related to common units held by the general partner) of approximately $10.5 million.
	Distributions to Class A Preferred Unit Holders
	Our partnership agreement requires us to make quarterly distributions to our Class A Preferred Unit holders. The holders of our Class A Preferred Units (the Preferred Units) are entitled to receive fixed quarterly distributions of $0.5804 per unit. For the 12 quarters following the quarter ended June 30, 2014 (the Initial Distribution Period), distributions on our Preferred Units can be made in additional Preferred Units, cash, or a combination thereof, at our election. If we elect to pay the quarterly distribution through the issuance of additional Preferred Units, the number of units to be distributed will be calculated as the fixed quarterly distribution of $0.5804 per unit divided by the cash purchase price of $25.10 per unit. We accrue the fair value of such distribution at the end of the quarterly period and adjust the fair value of the distribution on the date the additional Preferred Units are distributed. Distributions on our Preferred Units following the Initial Distribution Period will be made in cash unless, subject to certain exceptions, (i) there is no distribution being paid on our common units and (ii) our available cash (as defined in our partnership agreement) is insufficient to make a cash distribution to our Preferred Unit holders. If we fail to pay the full amount payable to our Preferred Unit holders in cash following the Initial Distribution Period, then (x) the fixed quarterly distribution on the Preferred Units will increase to $0.7059 per unit, and (y) we will not be permitted to declare or make any distributions to our common unitholders until such time as all accrued and unpaid distributions on the Preferred Units have been paid in full in cash. In addition, if we fail to pay in full any Class A Preferred Distribution (as defined in our partnership agreement), the amount of such unpaid distribution will accrue and accumulate from the last day of the quarter for which such distribution is due until paid in full, and any accrued and unpaid distributions will be increased at a rate of 2.8125% per quarter.
	On April 23, 2015, the board of directors of our general partner authorized the issuance of 423,903 Class A Preferred Units to our preferred unitholders for the quarter ended March 31, 2015 in lieu of paying a cash distribution. On February 13, 2015, we issued 414,325 Class A Preferred Units to our preferred unitholders for the quarter ended December 31, 2014 in lieu of paying a cash distribution.
	Distributions to Limited Partners
	The following table presents quarterly cash distributions paid to our limited partners (excluding distributions paid to our general partner on its common units held) during the three months ended March 31, 2015 and 2014:
	Record Date	Payment Date	Per Unit Rate		Cash Distribution
					(in millions)
	2015
	February 6, 2015	February 13, 2015	$	0.41	$	74.3
	2014
	February 7, 2014	February 14, 2014	$	0.41	$	74.1
	On April 23, 2015, we declared a distribution of $0.41 per limited partner unit to be paid on May 15, 2015, to unitholders of record on May 8, 2015 with respect to the first quarter of 2015.
	Non-Controlling Partners
	Crestwood Niobrara issued a preferred interest to a subsidiary of General Electric Capital Corporation and GE Structured Finance, Inc. (collectively, GE) in conjunction with the acquisition of its investment in Jackalope, which is reflected as non-controlling interest in our consolidated financial statements. During the three months ended March 31, 2014, GE made capital contributions of $12.3 million to Crestwood Niobrara in exchange for an equivalent number of preferred units. During the three months ended March 31, 2015 and 2014, Crestwood Niobrara issued 3,680,570 and 2,210,294 preferred units to GE in lieu of paying a cash distribution. Beginning in the first quarter of 2015, Crestwood Niobrara no longer had the option to pay distributions to GE by issuing additional preferred units in lieu of paying a cash distribution. On April 30, 2015, Crestwood Niobrara paid a distribution of $3.8 million to GE for the quarter ended March 31, 2015.

Equity_Plans_Notes

Equity Plans (Notes)	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Long-Term Incentive Plan	Equity Plans
	Long-term incentive awards are granted under the Crestwood Midstream Partners LP Long Term Incentive Plan (Crestwood LTIP) in order to align the economic interests of key employees and directors with those of Crestwood's common unitholders and to provide an incentive for continuous employment. Long-term incentive compensation consist of grants of restricted and phantom common units (which represent limited partner interests of Company) which vest based upon continued service.
	Crestwood LTIP
	The following table summarizes information regarding restricted unit activity during the three months ended March 31, 2015:
			Units		Weighted-Average Grant Date Fair Value
	Unvested - January 1, 2015		834,796		$	23.18
	Vested - restricted units		(424,653	)	$	23.11
	Granted - restricted units		512,404		$	16.01
	Granted - phantom units		161,039		$	16.02
	Forfeited(1)		(37,997	)	$	20.93
	Unvested - March 31, 2015		1,045,589		$	18.68
	-1	We implemented a company-wide initiative to reduce operating costs in 2015 and beyond, which included a reduction in work force. As a result, 21,583 restricted units were forfeited during the three months ended March 31, 2015.
	As of March 31, 2015 and December 31, 2014, we had total unamortized compensation expense of approximately $15.7 million and $9.5 million related to restricted and phantom units, which we expect will be amortized during the next three years (or sooner in certain cases, which generally represents the original vesting period of these instruments), except for grants to non-employee directors of our general partner, which vest over one year. We recognized compensation expense of approximately $3.0 million and $2.9 million during the three months ended March 31, 2015 and 2014, which is included in general and administrative expenses on our consolidated statements of operations. An additional $2.2 million and $1.7 million of net compensation expense was allocated from CEQP to us during the three months ended March 31, 2015 and 2014 (see Note 11). We granted restricted and phantom units with a grant date fair value of approximately $8.2 million and $2.6 million during the three months ended March 31, 2015.  As of March 31, 2015, we had 17,199,153 units available for issuance under the Crestwood LTIP.
	Restricted Units. Under the Crestwood LTIP, participants who have been granted restricted units may elect to have common units withheld to satisfy minimum statutory tax withholding obligations arising in connection with the vesting of non-vested common units. Any such common units withheld are returned to the Crestwood LTIP on the applicable vesting dates, which correspond to the times at which income is recognized by the employee. When we withhold these common units, we are required to remit to the appropriate taxing authorities the fair value of the units withheld as of the vesting date. The number of units withheld is determined based on the closing price per common unit as reported on the NYSE on such dates. During the three months ended March 31, 2015 and 2014, we withheld 134,591 and 7,456 common units to satisfy employee tax withholding obligations.
	Phantom Units.  The Crestwood LTIP currently permits, and our general partner has made, grants of phantom units. Each phantom unit entitles the holder thereof to receive upon vesting one common unit of CMLP granted pursuant to the Crestwood LTIP and a phantom unit award agreement (the Phantom Unit Agreement). The Phantom Unit Agreement provides for vesting to occur at the end of three years following the grant date or, if earlier, upon the named executive officer's termination without cause or due to death or disability or the named executive officer's resignation for employee cause (each, as defined in the Phantom Unit Agreement). In addition, the Phantom Unit Agreement provides for distribution equivalent rights with respect to each phantom unit which are paid in additional phantom units and settled in common units upon vesting of the underlying phantom units.
	Employee Unit Purchase Plan
	We have an employee unit purchase plan under which employees of the general partner may purchase our common units through payroll deductions up to a maximum of 10% of the employees' eligible compensation. Under the plan, we may purchase our common units on the open market for the benefit of participating employees based on their payroll deductions.  In addition, we may contribute an additional 10% of participating employees' payroll deductions to purchase additional Crestwood common units for participating employees. Unless increased by the board of directors of our general partner, the maximum number of units that may be purchased under the plan is 200,000. During the three months ended March 31, 2015, there were 2,011 common units purchased through the employee unit purchase plan related to the fourth quarter of 2014. In April 2015, there were 3,841 common units purchased related to the first quarter of 2015.

Commitments_and_Contingencies

Commitments and Contingencies	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies
	Legal Proceedings
	Canadian Class Action Lawsuit. Prior to the completion of our acquisition of Arrow on November 8, 2013, a train transporting over 50,000 barrels of crude oil produced in North Dakota derailed in Lac Megantic, Quebec, Canada on July 6, 2013. The derailment resulted in the death of 47 people, injured numerous others, and caused severe damage to property and the environment.  In October 2013, certain individuals suffering harm in the derailment filed a motion to certify a class action lawsuit in the Superior Court for the District of Megantic, Province of Quebec, Canada, on behalf of all persons suffering loss in the derailment (the Class Action Suit).
	In March 2014, the plaintiffs filed their fourth amended motion to name Arrow and numerous other energy companies as additional defendants in the class action lawsuit. The plaintiffs have named at least 53 defendants purportedly involved in the events leading up to the derailment, including the producers and sellers of the crude being transported, the midstream companies that transported the crude from the well head to the rail system, the manufacturers of the rail cars used to transport the crude, the railroad companies involved, the insurers of these companies, and the Canadian Attorney General.  The plaintiffs allege, among other things, that Arrow (i) was a producer of the crude oil being transported on the derailed train, (ii) was negligent in failing to properly classify the crude delivered to the trucks that hauled the crude to the rail loading terminal, and (iii) owed a duty to the petitioners to ensure the safe transportation of the crude being transported.  The motion to authorize the class action and motions in opposition were heard by the Court in June 2014.  We anticipate a ruling from the Judge on Petitioners' motion to authorize the class action in the first half of 2015.
	There are three other lawsuits related to the Class Action Suit. Montreal Main & Atlantic Railway filed bankruptcy actions in both the U.S. Bankruptcy Court for the District of Maine and in the Canadian Bankruptcy Court. In addition, a lawsuit was filed in Cook County, Illinois on behalf of the deceased claimants, which is currently stayed due to the bankruptcy proceeding. We are not currently named as a defendant in these additional lawsuits; however, we have been notified by the bankruptcy trustees of a proposal to contribute to a settlement in exchange for a release from all claims related to the Class Action Suit. We have evaluated this proposal and made a confidential contingent offer to the Bankruptcy Trustee.
	We will vigorously defend ourselves and, to the extent these actions proceed, we believe we have meritorious defenses to the claims.  Because these related actions are in the early stages of the proceeding, we are unable to estimate a reasonably possible loss or range of loss in this matter.  We also believe these claims are insurable under our insurance policy and we have notified our insurance company of them.
	When we were served with the Class Action Suit, we notified the former owners of the Arrow system that the claims alleged in the Class Action Suit would, if true, result in breaches of certain representations and warranties made by the former sellers in the agreement under which we acquired Arrow. As part of the acquisition, we deposited 3,309,797 of our common units into an escrow account to cover potential indemnification claims made by us on or before December 31, 2014. Subject to indemnification claims paid out with escrowed units and any outstanding claims outstanding at year end, all common units remaining in the escrow account on January 1, 2015 were to be released to the former owners. In December 2014, we notified the escrow agent of our indemnification notices delivered to the former owners and instructed the escrow agent not to release any escrowed units to the former owners. On February 19, 2015, we received a summons for an action filed against us in the Supreme Court of the State of New York (County of New York), under which the former owners have asserted our indemnification notices regarding the Class Action Suit and our notice to the escrow agent breach the terms of the merger and escrow agreements and the implied covenant of good faith and fair dealing.  The former owners have requested declaratory and injunctive relief, as well as monetary damages. Although our insurance policies would not cover this action, we believe we have meritorious defenses to this lawsuit and will aggressively defend ourselves. We are unable to estimate a reasonably possible loss or range of loss in this matter due to the recent filing of this lawsuit.
	General. We are periodically involved in litigation proceedings. If we determine that a negative outcome is probable and the amount of loss is reasonably estimable, then we accrue the estimated amount. The results of litigation proceedings cannot be predicted with certainty. We could incur judgments, enter into settlements or revise our expectations regarding the outcome of certain matters, and such developments could have a material adverse effect on our results of operations or cash flows in the period in which the amounts are paid and/or accrued. As of March 31, 2015 and December 31, 2014, we had less than $0.1 million accrued for our outstanding legal matters. Based on currently available information, we believe it is remote that future costs related to known contingent liability exposures for which we can estimate will exceed current accruals by an amount that would have a material adverse impact on our consolidated financial statements. As we learn new facts concerning contingencies, we reassess our position both with respect to accrued liabilities and other potential exposures.
	Any loss estimates are inherently subjective, based on currently available information, and are subject to management's judgment and various assumptions. Due to the inherently subjective nature of these estimates and the uncertainty and unpredictability surrounding the outcome of legal proceedings, actual results may differ materially from any amounts that have been accrued.
	Regulatory Compliance
	In the ordinary course of our business, we are subject to various laws and regulations. In the opinion of our management, compliance with current laws and regulations will not have a material effect on our results of operations, cash flows or financial condition.
	Environmental Compliance
	During 2014, we experienced three releases totaling approximately 28,000 barrels of produced water on our Arrow water gathering system located on the Fort Berthold Indian Reservation in North Dakota. We immediately notified the National Response Center, the Three Affiliated Tribes and numerous other regulatory authorities, and thereafter contained and cleaned up the releases completely and placed the impacted segments of these water lines back into service. We will continue our remediation efforts to ensure the impacted lands are restored to their prior state. We believe these releases are insurable events under our policies, and we have notified our carriers of these events. We have not recorded an insurance receivable as of March 31, 2015. In May 2015, we experienced a release of up to 8,000 barrels of produced water on our Arrow water gathering system, and immediately notified numerous regulatory authorities and other third parties.  We are currently evaluating the extent of the release and its impact on the related lands, and because this matter is in the early stages of investigation, we are unable to estimate a reasonably possible loss or range of loss.
	We may potentially be subject to fines and penalties as a result of the water releases.  We received data requests from the Environmental Protection Agency (EPA) related to the releases in October 2014, responded to the EPA’s original request for information in January 2015, and are working to respond to supplemental requests received from the EPA in the first quarter of 2015.  On April 16, 2015, the EPA issued a Notice of Potential Violation relating to the water releases, and we anticipate responding to the Notice of Potential Violation in May 2015. On March 3, 2015, we received a grand jury subpoena from the United States Attorney’s Office in Bismarck, North Dakota, seeking documents and information relating to the largest of the three releases, and we are in the process of providing the requested information. We cannot predict what the outcome of these investigations will be, and we had no amounts accrued for fines or penalties as of March 31, 2015.
	Our operations are subject to stringent and complex laws and regulations pertaining to health, safety, and the environment. We are subject to laws and regulations at the federal, state and local levels that relate to air and water quality, hazardous and solid waste management and disposal and other environmental matters. The cost of planning, designing, constructing and operating our facilities must incorporate compliance with environmental laws and regulations and safety standards. Failure to comply with these laws and regulations may trigger a variety of administrative, civil and potentially criminal enforcement measures. At March 31, 2015 and December 31, 2014, our accrual of approximately $0.3 million and $1.1 million was primarily related to the Arrow water releases described above, which is based on our undiscounted estimate of amounts we will spend on compliance with environmental and other regulations. We estimate that our potential liability for reasonably possible outcomes related to our environmental exposures (including the Arrow water releases described above) could range from approximately $0.3 million to $0.8 million.
	Contingent Consideration - Antero
	In connection with the acquisition of Antero Resources Appalachian Corporation (Antero), we agreed to pay Antero conditional consideration in the form of potential additional cash payments of up to $40.0 million, depending on the achievement of certain defined average annual production levels achieved during 2012, 2013 and 2014. In February 2015, we paid Antero $40.0 million to settle the liability under the earn-out provision. This amount is reflected in changes in operating assets and liabilities, net of effects from acquisitions under operating activities in our consolidated statements of cash flows.

Related_Party_Transactions

Related Party Transactions	3 Months Ended
	Mar. 31, 2015
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions
	We do not have any employees. We share common management, general and administrative and overhead costs with CEQP. We have an omnibus agreement with CEQP that requires us to reimburse CEQP for all shared costs incurred on our behalf, except for certain unit based compensation costs which are treated as capital transactions. Due to the nature of these shared costs, it is not practicable to estimate what the costs would have been on a stand-alone basis. Accordingly, the accompanying financial statements may not necessarily be indicative of the conditions that would have existed, or the results of operations that would have occurred, if we operated as a stand-alone entity.
	The following table shows revenues, costs of goods sold and general and administrative expenses from our affiliates for the three months ended March 31, 2015 and 2014 (in millions):
			Three Months Ended
			March 31,
			2015			2014
	Gathering and processing revenues		$	1.2		$	0.9
	NGL and crude services revenues		$	3.4		$	3.3
	Gathering and processing costs of product/services sold (1)		$	8.3		$	11
	General and administrative expenses (2)		$	17.4		$	19.6
	Reimbursement of operations and maintenance expenses		$	0.9		$	—
	-1	Represents natural gas purchases from Sabine Oil and Gas LLC.
	-2	Included in general and administrative expenses is approximately $2.2 million and $1.7 million of net unit-based compensation charges allocated to us from CEQP for the three months ended March 31, 2015 and 2014.
	The following table shows accounts receivable and accounts payable from our affiliates as of March 31, 2015 and December 31, 2014 (in millions):
		March 31, 2015			December 31, 2014
	Accounts receivable	$	1.1		$	0.3
	Accounts payable	$	5.5		$	6.3
	For additional information regarding our related party transactions, see our 2014 Annual Report on Form 10-K filed with the SEC.

Segments

Segments	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Segments	Segments
	Financial Information
	We have three operating and reportable segments; (i) gathering and processing operations; (ii) storage and transportation operations; and (iii) NGL and crude services operations. Our gathering and processing operations engage in the gathering, processing, treating, compression, transportation and sales of natural gas and the delivery of NGLs. Our storage and transportation operations provide regulated natural gas storage and transportations services to producers, utilities and other customers. Our NGL and crude services operations provide NGLs and crude oil gathering, storage, marketing and transportation services to producers, refiners, marketers and other customers that effectively provide flow assurances to our customers, as well as the production and sale of salt products. Our corporate operations include all general and administrative expenses that are not allocated to the reportable segments. We assess the performance of our operating segments based on EBITDA, which represents operating income plus depreciation, amortization and accretion expense.
	Below is a reconciliation of net income to EBITDA (in millions):
			Three Months Ended
			March 31,
			2015			2014
	Net income		$	21.7		$	5.5
	Add:
	Interest and debt expense, net		29.9			28.1
	Provision for income taxes		0.3			0.7
	Depreciation, amortization and accretion		59.9			50.8
	EBITDA		$	111.8		$	85.1
	The following tables summarize the reportable segment data for the three months ended March 31, 2015 and 2014 (in millions).
		Three Months Ended March 31, 2015
		Gathering and Processing			Storage and Transportation			NGL and Crude Services			Corporate			Total
	Revenues	$	78.5		$	45.7		$	330.9		$	—		$	455.1
	Costs of product/services sold	12.7			3.3			270.6			—			286.6
	Operations and maintenance expense	14.9			4.3			15.9			—			35.1
	General and administrative expense	—			—			—			24.2			24.2
	Loss on long-lived assets	(0.3		)	(0.5		)	—			—			(0.8		)
	Earnings from unconsolidated affiliates, net	2.5			0.9			—			—			3.4
	EBITDA	$	53.1		$	38.5		$	44.4		$	(24.2	)	$	111.8
	Goodwill	$	81.1		$	726.3		$	825.2		$	—		$	1,632.60
	Total assets	$	1,969.60		$	1,976.10		$	2,514.00		$	153		$	6,612.70
	Purchases of property, plant and equipment	$	11.4		$	2.7		$	29.1		$	0.1		$	43.3
		Three Months Ended March 31, 2014
		Gathering and Processing			Storage and Transportation			NGL and Crude Services			Corporate			Total
	Revenues	$	79.5		$	44.3		$	413.2		$	—		$	537
	Costs of product/services sold	18.7			3.2			376.2			—			398.1
	Operations and maintenance expense	13.4			4.3			10.3			—			28
	General and administrative expense	—			—			—			24.1			24.1
	Gain on long-lived assets	0.5			—			—			—			0.5
	Loss on contingent consideration	(2.1		)	—			—			—			(2.1		)
	Earnings (loss) from unconsolidated affiliates, net	0.3			—			(0.4		)	—			(0.1		)
	EBITDA	$	46.1		$	36.8		$	26.3		$	(24.1	)	$	85.1
	Goodwill	$	99.6		$	728.6		$	861.1		$	—		$	1,689.30
	Total assets	$	1,881.60		$	1,975.50		$	2,478.00		$	156.3		$	6,491.40
	Purchases of property, plant and equipment	$	46.3		$	1.2		$	28.9		$	0.9		$	77.3

Condensed_Consolidating_Financ

Condensed Consolidating Financial Information (Notes)	3 Months Ended
	Mar. 31, 2015
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Condensed Consolidating Financial Information	Condensed Consolidating Financial Information
	Crestwood is a holding company and owns no operating assets and has no significant operations independent of our subsidiaries. Obligations under our Senior Notes and our Credit Facility are jointly and severally guaranteed by substantially all of our subsidiaries, except for Crestwood Niobrara, PRBIC and Tres Holdings and their respective subsidiaries (collectively, Non-Guarantor Subsidiaries). Crestwood Midstream Finance Corp., the co-issuer of our Senior Notes, is our 100% owned subsidiary and has no material assets, operations, revenues or cash flows other than those related to its service as co-issuer of our Senior Notes.
	As summarized in the table below, the condensed consolidating financial statements for the three months ended March 31, 2014 have been corrected for certain errors in presentation. There was no impact to our consolidated statement of operations or our consolidated statement of cash flows for the three months ended March 31, 2014.
		Parent						Guarantor						Eliminations
								Subsidiaries
		As Adjusted			As Previously Reported			As Adjusted			As Previously Reported			As Adjusted			As Previously Reported
		(in millions)
	General and administrative expense	$	17		$	(2.1	)	$	7.1		$	26.2		$	—		$	—
	Operating income (loss)	(17.2		)	1.9			51.6			32.5			—			—
	Equity in net income (loss) of subsidiary	50.8			31.7			—			—			(50.8		)	(31.7		)
	Income (loss) before income taxes	5.5			5.5			51.6			32.5			(50.8		)	(31.7		)
	Net income (loss)	5.5			5.5			50.9			31.8			(50.8		)	(31.7		)
	Net income (loss) attributable to Crestwood Midstream Partners LP	5.5			5.5			50.9			31.8			(50.8		)	(31.7		)
		Parent						Guarantor						Non-Guarantor						Eliminations
								Subsidiaries						Subsidiaries
		As Adjusted			As Previously Reported			As Adjusted			As Previously Reported			As Adjusted			As Previously Reported			As Adjusted			As Previously Reported
		(in millions)
	Cash flows from operating activities:	$	(39.6	)	$	5.8		$	107.3		$	52.3		$	—		$	—		$	—		$	—
	Cash flows from investing activities:
	Investment in unconsolidated affiliates, net	—			—			—			(2.5		)	(19.8		)	(17.3		)	—			—
	Capital contributions from consolidated affiliates	(6.5		)	(4.0		)	—			—			—			—			6.5			4
	Other	—			(2.4		)	—			—			—			—			—			2.4
	Net cash provided by (used in) investing activities	(7.4		)	(7.3		)	(88.5		)	(81.4		)	(19.8		)	(17.3		)	6.5			6.4
	Cash flows from financing activities:
	Proceeds from the issuance of long-term debt	306			2.5			—			303.5			—			—			—			—
	Principal payments on long-term debt	(188.8		)	—			—			(188.8		)	—			—			—			—
	Distributions paid	(84.6		)	—			—			(84.6		)	—			—			—			—
	Contributions from parent	—			—			—			—			6.5			4			(6.5		)	(4.0		)
	Change in intercompany balances	15.4			—			(15.4		)	2.4			—			—			—			(2.4		)
	Net cash provided by (used in) financing activities	47.7			2.2			(16.2		)	31.7			18.8			16.3			(6.5		)	(6.4		)
	The tables below present condensed consolidating financial statements for us (parent) on a stand-alone, unconsolidated basis, and our combined guarantor and combined non-guarantor subsidiaries as of March 31, 2015 and December 31, 2014, and for the three months ended March 31, 2015 and 2014.  The financial information may not necessarily be indicative of the results of operations, cash flows or financial position had the subsidiaries operated as independent entities.
	Condensed Consolidating Balance Sheet
	31-Mar-15
	(in millions)
		Parent			Guarantor			Non-			Eliminations			Consolidated
					Subsidiaries			Guarantor
								Subsidiaries
	Assets
	Current assets:
	Cash	$	—		$	66.8		$	—		$	—		$	66.8
	Accounts receivable	0.9			190.6			—			—			191.5
	Accounts receivable - related party	—			—			1.1			—			1.1
	Total accounts receivable	0.9			190.6			1.1			—			192.6
	Inventories	—			9.2			—			—			9.2
	Other current assets	—			23.6			—			—			23.6
	Total current assets	0.9			290.2			1.1			—			292.2
	Property, plant and equipment, net	7.3			3,498.10			—			—			3,505.40
	Goodwill and intangible assets, net	47			2,450.30			—			—			2,497.30
	Investment in consolidated affiliates	6,359.50			—			—			(6,359.5		)	—
	Investment in unconsolidated affiliates	—			—			316.6			—			316.6
	Other assets	—			1.2			—			—			1.2
	Total assets	$	6,414.70		$	6,239.80		$	317.7		$	(6,359.5	)	$	6,612.70
	Liabilities and partners' capital
	Current liabilities:
	Accounts payable	$	1.3		$	121.8		$	—		$	—		$	123.1
	Accounts payable - related party	3.2			1.3			1			—			5.5
	Total accounts payable	4.5			123.1			1			—			128.6
	Other current liabilities	49.5			43.6			—			—			93.1
	Total current liabilities	54			166.7			1			—			221.7
	Long-term liabilities:
	Long-term debt, less current portion	2,121.70			—			—			—			2,121.70
	Other long-term liabilities	1.2			30.3			—			—			31.5
	Partners' capital	4,060.50			6,042.80			139.4			(6,182.2		)	4,060.50
	Interest of non-controlling partners in subsidiaries	177.3			—			177.3			(177.3		)	177.3
Total partners' capital	4,237.80			6,042.80			316.7			(6,359.5		)	4,237.80
Total liabilities and partners' capital	$	6,414.70		$	6,239.80		$	317.7		$	(6,359.5	)	$	6,612.70
Condensed Consolidating Balance Sheet
31-Dec-14
(in millions)
	Parent			Guarantor			Non-			Eliminations			Consolidated
				Subsidiaries			Guarantor
							Subsidiaries
Assets
Current assets:
Cash	$	—		$	4.6		$	—		$	—		$	4.6
Accounts receivable	1.2			240.3			—			—			241.5
Accounts receivable - related party	—			—			0.3			—			0.3
Total accounts receivable	1.2			240.3			0.3			—			241.8
Inventories	—			8			—			—			8
Other current assets	—			18.7			—			—			18.7
Total current assets	1.2			271.6			0.3			—			273.1
Property, plant and equipment, net	7.9			3,510.20			—			—			3,518.10
Goodwill and intangible assets, net	38			2,470.80			—			—			2,508.80
Investment in consolidated affiliates	6,296.70			—			—			(6,296.7		)	—
Investment in unconsolidated affiliates	—			—			295.1			—			295.1
Other assets	—			1.4			—			—			1.4
Total assets	$	6,343.80		$	6,254.00		$	295.4		$	(6,296.7	)	$	6,596.50
Liabilities and partners' capital
Current liabilities:
Accounts payable	$	4.8		$	121.3		$	—		$	—		$	126.1
Accounts payable - related party	4.2			1.9			0.2			—			6.3
Total accounts payable	9			123.2			0.2			—			132.4
Other current liabilities	23			99.7			—			—			122.7
Total current liabilities	32			222.9			0.2			—			255.1
Long-term liabilities:
Long-term debt, less current portion	2,012.80			—			—			—			2,012.80
Other long-term liabilities	1.6			29.6			—			—			31.2
Partners' capital	4,125.70			6,001.50			123.5			(6,125.0		)	4,125.70
Interest of non-controlling partners in subsidiaries	171.7			—			171.7			(171.7		)	171.7
Total partners' capital	4,297.40			6,001.50			295.2			(6,296.7		)	4,297.40
Total liabilities and partners' capital	$	6,343.80		$	6,254.00		$	295.4		$	(6,296.7	)	$	6,596.50
Condensed Consolidating Statements of Operations
Three Months Ended March 31, 2015
(in millions)
	Parent			Guarantor			Non-			Eliminations			Consolidated
				Subsidiaries			Guarantor
							Subsidiaries
Revenues	$	—		$	455.1		$	—		$	—		$	455.1
Costs of product/services sold	—			286.6			—			—			286.6
Expenses:
Operations and maintenance	—			35.1			—			—			35.1
General and administrative	13.4			10.8			—			—			24.2
Depreciation, amortization and accretion	0.2			59.7			—			—			59.9
	13.6			105.6			—			—			119.2
Other operating income (expense):
Loss on long-lived assets, net	—			(0.8		)	—			—			(0.8		)
Operating income	(13.6		)	62.1			—			—			48.5
Earnings from unconsolidated affiliates, net	—			—			3.4			—			3.4
Interest and debt expense, net	(29.9		)	—			—			—			(29.9		)
Equity in net income (loss) of subsidiary	65.2			—			—			(65.2		)	—
Income (loss) before income taxes	21.7			62.1			3.4			(65.2		)	22
Provision for income taxes	—			0.3			—			—			0.3
Net income (loss)	21.7			61.8			3.4			(65.2		)	21.7
Net income attributable to non-controlling partners	—			—			(5.6		)	—			(5.6		)
Net income (loss) attributable to Crestwood Midstream Partners LP	21.7			61.8			(2.2		)	(65.2		)	16.1
Net income attributable to Class A preferred units	(9.2		)	—			—			—			(9.2		)
Net income (loss) attributable to partners	$	12.5		$	61.8		$	(2.2	)	$	(65.2	)	$	6.9
Condensed Consolidating Statements of Operations
Three Months Ended March 31, 2014
(in millions)
	Parent			Guarantor			Non-			Eliminations			Consolidated
				Subsidiaries			Guarantor
							Subsidiaries
Revenues	$	—		$	537		$	—		$	—		$	537
Costs of product/services sold	—			398.1			—			—			398.1
Expenses:
Operations and maintenance	—			28			—			—			28
General and administrative	17			7.1			—			—			24.1
Depreciation, amortization and accretion	0.2			50.6			—			—			50.8
	17.2			85.7			—			—			102.9
Other operating income (expense):
Gain on long-lived assets, net	—			0.5			—			—			0.5
Loss on contingent consideration	—			(2.1		)	—			—			(2.1		)
Operating income (loss)	(17.2		)	51.6			—			—			34.4
Loss from unconsolidated affiliates, net	—			—			(0.1		)	—			(0.1		)
Interest and debt expense, net	(28.1		)	—			—			—			(28.1		)
Equity in net income (loss) of subsidiary	50.8			—			—			(50.8		)	—
Income (loss) before income taxes	5.5			51.6			(0.1		)	(50.8		)	6.2
Provision for income taxes	—			0.7			—			—			0.7
Net income (loss)	5.5			50.9			(0.1		)	(50.8		)	5.5
Net income attributable to non-controlling partners	—			—			(3.1		)	—			(3.1		)
Net income (loss) attributable to Crestwood Midstream Partners LP	$	5.5		$	50.9		$	(3.2	)	$	(50.8	)	$	2.4
Condensed Consolidating Statements of Cash Flows
Three Months Ended March 31, 2015
(in millions)
	Parent			Guarantor			Non-			Eliminations			Consolidated
				Subsidiaries			Guarantor
							Subsidiaries
Cash flows from operating activities:	$	(54.8	)	$	131.8		$	—		$	—		$	77
Cash flows from investing activities:
Purchases of property, plant and equipment	(0.1		)	(43.2		)	—			—			(43.3		)
Investment in unconsolidated affiliates	—			—			(17.9		)	—			(17.9		)
Proceeds from sale of assets	—			0.3			—			—			0.3
Capital contribution to consolidated affiliates	(17.9		)	—			—			17.9			—
Net cash provided by (used in) investing activities	(18.0		)	(42.9		)	(17.9		)	17.9			(60.9		)
Cash flows from financing activities:
Proceeds from the issuance of long-term debt	1,114.60			—			—			—			1,114.60
Principal payments on long-term debt	(970.0		)	—			—			—			(970.0		)
Payments on capital leases	(0.5		)	(0.2		)	—			—			(0.7		)
Payments for debt-related deferred costs	(11.1		)	—			—			—			(11.1		)
Distributions paid	(84.8		)	—			—			—			(84.8		)
Contributions from parent	—			—			17.9			(17.9		)	—
Taxes paid for unit-based compensation vesting	—			(1.7		)	—			—			(1.7		)
Change in intercompany balances	24.8			(24.8		)	—			—			—
Other	(0.2		)	—			—			—			(0.2		)
Net cash provided by (used in) financing activities	72.8			(26.7		)	17.9			(17.9		)	46.1
Net change in cash	—			62.2			—			—			62.2
Cash at beginning of period	—			4.6			—			—			4.6
Cash at end of period	$	—		$	66.8		$	—		$	—		$	66.8
Condensed Consolidating Statements of Cash Flows
Three Months Ended March 31, 2014
(in millions)
	Parent			Guarantor			Non-			Eliminations			Consolidated
				Subsidiaries			Guarantor
							Subsidiaries
Cash flows from operating activities:	$	(39.6	)	$	107.3		$	—		$	—		$	67.7
Cash flows from investing activities:
Acquisitions, net of cash acquired	—			(12.1		)	—			—			(12.1		)
Purchases of property, plant and equipment	(0.9		)	(76.4		)	—			—			(77.3		)
Investment in unconsolidated affiliates	—			—			(19.8		)	—			(19.8		)
Capital contribution to consolidated affiliates	(6.5		)	—			—			6.5			—
Net cash provided by (used in) investing activities	(7.4		)	(88.5		)	(19.8		)	6.5			(109.2		)
Cash flows from financing activities:
Proceeds from the issuance of long-term debt	306			—			—			—			306
Principal payments on long-term debt	(188.8		)	—			—			—			(188.8		)
Payments on capital leases	(0.3		)	(0.8		)	—			—			(1.1		)
Distributions paid	(84.6		)	—			—			—			(84.6		)
Contributions from parent	—			—			6.5			(6.5		)	—
Net proceeds from issuance of preferred equity of subsidiary	—			—			12.3			—			12.3
Change in intercompany balances	15.4			(15.4		)	—			—			—
Net cash provided by (used in) financing activities	47.7			(16.2		)	18.8			(6.5		)	43.8
Net change in cash	0.7			2.6			(1.0		)	—			2.3
Cash at beginning of period	0.1			1.6			1			—			2.7
Cash at end of period	$	0.8		$	4.2		$	—		$	—		$	5

Basis_of_Presentation_and_Summ1

Basis of Presentation and Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Significant Accounting Policies	Significant Accounting Policies
	There were no material changes in our significant accounting policies from those described in our 2014 Annual Report on Form 10-K.
New Accounting Pronouncements Issued But Not Yet Adopted	New Accounting Pronouncements Issued But Not Yet Adopted
	As of March 31, 2015, the following accounting standards had not yet been adopted by us.
	In May 2014, the Financial Accounting Standards Board (FASB) issued Accounting Standards Update 2014-09, Revenue from Contracts with Customers, which outlines a single comprehensive model for entities to use in accounting for revenue arising from contracts with customers and supersedes current revenue recognition guidance. We expect to adopt the provisions of this standard effective January 1, 2017 and are currently evaluating the impact that this standard will have on our consolidated financial statements. In April 2015, the FASB proposed deferring the effective date of this standard by one year.
	In February 2015, the FASB issued Accounting Standards Update 2015-02, Consolidation (Topic 810): Amendments to the Consolidation Analysis, which provides additional guidance on the consolidation of limited partnerships and on the evaluation of variable interest entities. We expect to adopt the provisions of this standard effective January 1, 2016 and are currently evaluating the impact, if any, that this standard may have on our consolidated financial statements.
	In April 2015, the FASB issued Accounting Standards Update 2015-03, Interest - Imputation of Interest (Subtopic 835-30), which requires deferred debt issuance costs to be classified as a reduction of the debt liability rather than as an asset in the balance sheet. We expect to adopt the provisions of this standard effective January 1, 2016, and do not currently anticipate it will have a significant impact on our consolidated financial statements.

Certain_Balance_Sheet_Informat1

Certain Balance Sheet Information (Tables)	3 Months Ended
	Mar. 31, 2015
Balance Sheet Related Disclosures [Abstract]
Components of Property, Plant and Equipment	Property, plant and equipment consisted of the following at March 31, 2015 and December 31, 2014 (in millions):
		March 31,		December 31,
		2015		2014
	Gathering systems and pipelines	1,281.20		1,276.60
	Facilities and equipment	1,458.00		1,468.80
	Buildings, land, rights-of-way, storage contracts and easements	808.1		806.4
	Vehicles	14.1		13.6
	Construction in process	171.2		153.7
	Base gas	37.5		37.5
	Salt deposits	120.5		120.5
	Office furniture and fixtures	6.4		6.4
		3,897.00		3,883.50
	Less: accumulated depreciation and depletion	391.6		365.4
	Total property, plant and equipment, net	$	3,505.40	$	3,518.10
Components of Intangible Assets	Intangible assets consisted of the following at March 31, 2015 and December 31, 2014 (in millions):
		March 31,		December 31,
		2015		2014
	Customer accounts	$	483.2	$	483.2
	Covenants not to compete	5.6		5.6
	Gas gathering, compression and processing contracts	427.3		431.4
	Acquired storage contracts	29		29
	Trademarks	9.7		9.7
	Deferred financing costs	65.4		54.3
		1,020.20		1,013.20
	Less: accumulated amortization	155.5		137
	Total intangible assets, net	$	864.7	$	876.2
Components of Accrued Expenses and Other Liabilities	Accrued expenses and other liabilities consisted of the following at March 31, 2015 and December 31, 2014 (in millions):
		March 31,		December 31, 2014
		2015
	Accrued expenses	$	17.9	$	23.7
	Accrued property taxes	3.9		2.1
	Accrued product purchases payable	0.4		0.7
	Tax payable	—		0.4
	Interest payable	13.5		22
	Accrued additions to property, plant and equipment	9.1		20
	Commitments and contingent liabilities (Note 10)	—		40
	Capital leases	0.9		1.3
	Deferred revenue	11.3		11.6
	Other	—		0.2
	Total accrued expenses and other liabilities	$	57	$	122

Investments_in_Unconsolidated_1

Investments in Unconsolidated Affiliates (Tables)	3 Months Ended
	Mar. 31, 2015
Equity Method Investments and Joint Ventures [Abstract]
Equity Method Investments	Our net investments in and earnings (loss) from our unconsolidated affiliates are as follows (in millions, unless otherwise stated):
			Ownership Percentage			Investment				Earnings (Loss) from Unconsolidated Affiliates
			March 31,			March 31,		December 31,		Three Months Ended March 31,
			2015			2015		2014		2015		2014
	Jackalope Gas Gathering Services, L.L.C.(1)		50	%	(4)	$	244.2	$	232.9	$	2.5	$	0.3
	Tres Palacios Holdings LLC(2)		50.01	%		42.8		36		0.9		—
	Powder River Basin Industrial Complex, LLC(3)		50.01	%		29.6		26.2		—		(0.4		)
	Total					$	316.6	$	295.1	$	3.4	$	(0.1	)
	-1	As of March 31, 2015, our investment balance exceeded our equity in the underlying net assets of Jackalope Gas Gathering Services, L.L.C. (Jackalope)by approximately $52.9 million. We amortize and generally assess the recoverability of this amount over 20 years, which represents the life of Jackalope’s gathering agreement with Chesapeake Energy Corporation and RKI Exploration and Production, LLC, and reflect the amortization as a reduction of our earnings from unconsolidated affiliates. For the three months ended March 31, 2015 and 2014, we recorded amortization of approximately $0.8 million. Our Jackalope investment is included in our gathering and processing segment.
	-2	In December 2014, one of our consolidated subsidiaries and an affiliate of Brookfield Infrastructure Group (Brookfield) formed the Tres Palacios Holdings LLC (Tres Holdings) joint venture. For more information on our joint venture, see our 2014 Annual Report on Form 10-K filed with the SEC. As of March 31, 2015, our equity in the underlying net assets exceeded our investment balance in Tres Holdings by approximately $30.0 million. We amortize and generally assess the recoverability of this amount over the life of the Tres Palacios Gas Storage LLC (Tres Palacios) sublease agreement, and reflect the amortization as an increase of our earnings from unconsolidated affiliates. For the three months ended March 31, 2015, we recorded amortization of approximately $0.3 million. Our Tres Holdings investment is included in our storage and transportation segment.
	-3	As of March 31, 2015, our investment balance approximated our equity in the underlying net assets of Powder River Basin Industrial Complex, LLC (PRBIC). Our PRBIC investment is included in our NGL and crude services segment.
	-4	Excludes non-controlling interests related to our investment in Jackalope. See Note 8 for a further discussion of our non-controlling interest related to our investment in Jackalope.

Financial_Instruments_Tables

Financial Instruments (Tables)	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Schedule of Carrying Values and Estimated Fair Values of Debt Instruments	The following table reflects the carrying value and fair value of our senior notes (in millions):
		March 31, 2015				December 31, 2014
		Carrying Amount		Fair		Carrying Amount		Fair
				Value				Value
	2019 Senior Notes	$	350.9	$	363.6	$	351	$	360.5
	2020 Senior Notes	$	503.8	$	500.3	$	504	$	481.6
	2022 Senior Notes	$	600	$	607.5	$	600	$	568.5
	2023 Senior Notes	$	700	$	710.5	$	—	$	—
Schedule of Debt	Long-term debt consisted of the following at March 31, 2015 and December 31, 2014 (in millions):
		March 31,		December 31,
		2015		2014
	Credit Facility	$	—	$	555
	2019 Senior Notes	350		350
	Premium on 2019 Senior Notes	0.9		1
	2020 Senior Notes	500		500
	Fair value adjustment of 2020 Senior Notes	3.8		4
	2022 Senior Notes	600		600
	2023 Senior Notes	700		—
	Other	3.1		3.5
	Total debt	2,157.80		2,013.50
	Less: current portion	36.1		0.7
	Total long-term debt	$	2,121.70	$	2,012.80

Earnings_Per_Limited_Partner_U1

Earnings Per Limited Partner Unit (Tables)	3 Months Ended
	Mar. 31, 2015
Earnings Per Share [Abstract]
Schedule of Other Nonoperating Income (Expense)	The tables below show the (i) allocation of net income attributable to CMLP and the (ii) net income attributable to CMLP per limited partner unit based on the number of basic and diluted limited partner units outstanding for the three months ended March 31, 2015 and 2014 (in millions):
	Allocation of Net Income Attributable to CMLP
		Three Months Ended
		March 31,
		2015			2014
	Net income attributable to CMLP	$	16.1		$	2.4
	Class A preferred units’ interest in net income attributable to CMLP	(9.2		)	—
	General partner’s incentive distributions	(7.5		)	(7.5		)
	Limited partners’ interest in net income (loss) attributable to CMLP after incentive distributions	$	(0.6	)	$	(5.1	)
Schedule of Earnings Per Share Reconciliation
	Earnings Per Limited Partner Unit
		Three Months Ended
		March 31,
		2015			2014
	Limited partners’ interest in net income (loss)	$	(0.6	)	$	(5.1	)
	Weighted-average limited partner units - basic	188.3			187.8
	Effect of diluted units	—			—
	Weighted-average limited partner units - diluted	188.3			187.8
	Basic earnings per unit:
	Net income (loss) per limited partner	$	—		$	(0.03	)
	Diluted earnings per unit:
	Net income (loss) per limited partner	$	—		$	(0.03	)

Partners_Capital_Tables

Partners' Capital (Tables)	3 Months Ended
	Mar. 31, 2015
Partners' Capital [Abstract]
Schedule of Distributions Made to Members or Limited Partners, by Distribution	The following table presents quarterly cash distributions paid to our limited partners (excluding distributions paid to our general partner on its common units held) during the three months ended March 31, 2015 and 2014:
	Record Date	Payment Date	Per Unit Rate		Cash Distribution
					(in millions)
	2015
	February 6, 2015	February 13, 2015	$	0.41	$	74.3
	2014
	February 7, 2014	February 14, 2014	$	0.41	$	74.1

Equity_Plans_Tables

Equity Plans (Tables)	3 Months Ended
	Mar. 31, 2015
Equity [Abstract]
Disclosure of Share-based Compensation Arrangements by Share-based Payment Award	The following table summarizes information regarding restricted unit activity during the three months ended March 31, 2015:
			Units		Weighted-Average Grant Date Fair Value
	Unvested - January 1, 2015		834,796		$	23.18
	Vested - restricted units		(424,653	)	$	23.11
	Granted - restricted units		512,404		$	16.01
	Granted - phantom units		161,039		$	16.02
	Forfeited(1)		(37,997	)	$	20.93
	Unvested - March 31, 2015		1,045,589		$	18.68
	-1	We implemented a company-wide initiative to reduce operating costs in 2015 and beyond, which included a reduction in work force. As a result, 21,583 restricted units were forfeited during the three months ended March 31, 2015.

Related_Party_Transactions_Tab

Related Party Transactions (Tables)	3 Months Ended
	Mar. 31, 2015
Related Party Transactions [Abstract]
Schedule of Related Party Transactions	The following table shows revenues, costs of goods sold and general and administrative expenses from our affiliates for the three months ended March 31, 2015 and 2014 (in millions):
			Three Months Ended
			March 31,
			2015			2014
	Gathering and processing revenues		$	1.2		$	0.9
	NGL and crude services revenues		$	3.4		$	3.3
	Gathering and processing costs of product/services sold (1)		$	8.3		$	11
	General and administrative expenses (2)		$	17.4		$	19.6
	Reimbursement of operations and maintenance expenses		$	0.9		$	—
	-1	Represents natural gas purchases from Sabine Oil and Gas LLC.
	-2	Included in general and administrative expenses is approximately $2.2 million and $1.7 million of net unit-based compensation charges allocated to us from CEQP for the three months ended March 31, 2015 and 2014.
Schedule of Related Party Receivables and Payables	The following table shows accounts receivable and accounts payable from our affiliates as of March 31, 2015 and December 31, 2014 (in millions):
		March 31, 2015			December 31, 2014
	Accounts receivable	$	1.1		$	0.3
	Accounts payable	$	5.5		$	6.3

Segments_Tables

Segments (Tables)	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Reportable Segments	Below is a reconciliation of net income to EBITDA (in millions):
			Three Months Ended
			March 31,
			2015			2014
	Net income		$	21.7		$	5.5
	Add:
	Interest and debt expense, net		29.9			28.1
	Provision for income taxes		0.3			0.7
	Depreciation, amortization and accretion		59.9			50.8
	EBITDA		$	111.8		$	85.1
	The following tables summarize the reportable segment data for the three months ended March 31, 2015 and 2014 (in millions).
		Three Months Ended March 31, 2015
		Gathering and Processing			Storage and Transportation			NGL and Crude Services			Corporate			Total
	Revenues	$	78.5		$	45.7		$	330.9		$	—		$	455.1
	Costs of product/services sold	12.7			3.3			270.6			—			286.6
	Operations and maintenance expense	14.9			4.3			15.9			—			35.1
	General and administrative expense	—			—			—			24.2			24.2
	Loss on long-lived assets	(0.3		)	(0.5		)	—			—			(0.8		)
	Earnings from unconsolidated affiliates, net	2.5			0.9			—			—			3.4
	EBITDA	$	53.1		$	38.5		$	44.4		$	(24.2	)	$	111.8
	Goodwill	$	81.1		$	726.3		$	825.2		$	—		$	1,632.60
	Total assets	$	1,969.60		$	1,976.10		$	2,514.00		$	153		$	6,612.70
	Purchases of property, plant and equipment	$	11.4		$	2.7		$	29.1		$	0.1		$	43.3
		Three Months Ended March 31, 2014
		Gathering and Processing			Storage and Transportation			NGL and Crude Services			Corporate			Total
	Revenues	$	79.5		$	44.3		$	413.2		$	—		$	537
	Costs of product/services sold	18.7			3.2			376.2			—			398.1
	Operations and maintenance expense	13.4			4.3			10.3			—			28
	General and administrative expense	—			—			—			24.1			24.1
	Gain on long-lived assets	0.5			—			—			—			0.5
	Loss on contingent consideration	(2.1		)	—			—			—			(2.1		)
	Earnings (loss) from unconsolidated affiliates, net	0.3			—			(0.4		)	—			(0.1		)
	EBITDA	$	46.1		$	36.8		$	26.3		$	(24.1	)	$	85.1
	Goodwill	$	99.6		$	728.6		$	861.1		$	—		$	1,689.30
	Total assets	$	1,881.60		$	1,975.50		$	2,478.00		$	156.3		$	6,491.40
	Purchases of property, plant and equipment	$	46.3		$	1.2		$	28.9		$	0.9		$	77.3

Condensed_Consolidating_Financ1

Condensed Consolidating Financial Information (Tables)	3 Months Ended
	Mar. 31, 2015																Mar. 31, 2014
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Schedule of Error Corrections and Prior Period Adjustments [Table Text Block]																	As summarized in the table below, the condensed consolidating financial statements for the three months ended March 31, 2014 have been corrected for certain errors in presentation. There was no impact to our consolidated statement of operations or our consolidated statement of cash flows for the three months ended March 31, 2014.
																		Parent						Guarantor						Eliminations
																								Subsidiaries
																		As Adjusted			As Previously Reported			As Adjusted			As Previously Reported			As Adjusted			As Previously Reported
																		(in millions)
																	General and administrative expense	$	17		$	(2.1	)	$	7.1		$	26.2		$	—		$	—
																	Operating income (loss)	(17.2		)	1.9			51.6			32.5			—			—
																	Equity in net income (loss) of subsidiary	50.8			31.7			—			—			(50.8		)	(31.7		)
																	Income (loss) before income taxes	5.5			5.5			51.6			32.5			(50.8		)	(31.7		)
																	Net income (loss)	5.5			5.5			50.9			31.8			(50.8		)	(31.7		)
																	Net income (loss) attributable to Crestwood Midstream Partners LP	5.5			5.5			50.9			31.8			(50.8		)	(31.7		)
																		Parent						Guarantor						Non-Guarantor						Eliminations
																								Subsidiaries						Subsidiaries
																		As Adjusted			As Previously Reported			As Adjusted			As Previously Reported			As Adjusted			As Previously Reported			As Adjusted			As Previously Reported
																		(in millions)
																	Cash flows from operating activities:	$	(39.6	)	$	5.8		$	107.3		$	52.3		$	—		$	—		$	—		$	—
																	Cash flows from investing activities:
																	Investment in unconsolidated affiliates, net	—			—			—			(2.5		)	(19.8		)	(17.3		)	—			—
																	Capital contributions from consolidated affiliates	(6.5		)	(4.0		)	—			—			—			—			6.5			4
																	Other	—			(2.4		)	—			—			—			—			—			2.4
																	Net cash provided by (used in) investing activities	(7.4		)	(7.3		)	(88.5		)	(81.4		)	(19.8		)	(17.3		)	6.5			6.4
																	Cash flows from financing activities:
																	Proceeds from the issuance of long-term debt	306			2.5			—			303.5			—			—			—			—
																	Principal payments on long-term debt	(188.8		)	—			—			(188.8		)	—			—			—			—
																	Distributions paid	(84.6		)	—			—			(84.6		)	—			—			—			—
																	Contributions from parent	—			—			—			—			6.5			4			(6.5		)	(4.0		)
																	Change in intercompany balances	15.4			—			(15.4		)	2.4			—			—			—			(2.4		)
																	Net cash provided by (used in) financing activities	47.7			2.2			(16.2		)	31.7			18.8			16.3			(6.5		)	(6.4		)
Consolidating Balance Sheet
	Condensed Consolidating Balance Sheet
	31-Mar-15
	(in millions)
		Parent			Guarantor			Non-			Eliminations			Consolidated
					Subsidiaries			Guarantor
								Subsidiaries
	Assets
	Current assets:
	Cash	$	—		$	66.8		$	—		$	—		$	66.8
	Accounts receivable	0.9			190.6			—			—			191.5
	Accounts receivable - related party	—			—			1.1			—			1.1
	Total accounts receivable	0.9			190.6			1.1			—			192.6
	Inventories	—			9.2			—			—			9.2
	Other current assets	—			23.6			—			—			23.6
	Total current assets	0.9			290.2			1.1			—			292.2
	Property, plant and equipment, net	7.3			3,498.10			—			—			3,505.40
	Goodwill and intangible assets, net	47			2,450.30			—			—			2,497.30
	Investment in consolidated affiliates	6,359.50			—			—			(6,359.5		)	—
	Investment in unconsolidated affiliates	—			—			316.6			—			316.6
	Other assets	—			1.2			—			—			1.2
	Total assets	$	6,414.70		$	6,239.80		$	317.7		$	(6,359.5	)	$	6,612.70
	Liabilities and partners' capital
	Current liabilities:
	Accounts payable	$	1.3		$	121.8		$	—		$	—		$	123.1
	Accounts payable - related party	3.2			1.3			1			—			5.5
	Total accounts payable	4.5			123.1			1			—			128.6
	Other current liabilities	49.5			43.6			—			—			93.1
	Total current liabilities	54			166.7			1			—			221.7
	Long-term liabilities:
	Long-term debt, less current portion	2,121.70			—			—			—			2,121.70
	Other long-term liabilities	1.2			30.3			—			—			31.5
	Partners' capital	4,060.50			6,042.80			139.4			(6,182.2		)	4,060.50
	Interest of non-controlling partners in subsidiaries	177.3			—			177.3			(177.3		)	177.3
	Total partners' capital	4,237.80			6,042.80			316.7			(6,359.5		)	4,237.80
	Total liabilities and partners' capital	$	6,414.70		$	6,239.80		$	317.7		$	(6,359.5	)	$	6,612.70
	Condensed Consolidating Balance Sheet
	31-Dec-14
	(in millions)
		Parent			Guarantor			Non-			Eliminations			Consolidated
					Subsidiaries			Guarantor
								Subsidiaries
	Assets
	Current assets:
	Cash	$	—		$	4.6		$	—		$	—		$	4.6
	Accounts receivable	1.2			240.3			—			—			241.5
	Accounts receivable - related party	—			—			0.3			—			0.3
	Total accounts receivable	1.2			240.3			0.3			—			241.8
	Inventories	—			8			—			—			8
	Other current assets	—			18.7			—			—			18.7
	Total current assets	1.2			271.6			0.3			—			273.1
	Property, plant and equipment, net	7.9			3,510.20			—			—			3,518.10
	Goodwill and intangible assets, net	38			2,470.80			—			—			2,508.80
	Investment in consolidated affiliates	6,296.70			—			—			(6,296.7		)	—
	Investment in unconsolidated affiliates	—			—			295.1			—			295.1
	Other assets	—			1.4			—			—			1.4
	Total assets	$	6,343.80		$	6,254.00		$	295.4		$	(6,296.7	)	$	6,596.50
	Liabilities and partners' capital
	Current liabilities:
	Accounts payable	$	4.8		$	121.3		$	—		$	—		$	126.1
	Accounts payable - related party	4.2			1.9			0.2			—			6.3
	Total accounts payable	9			123.2			0.2			—			132.4
	Other current liabilities	23			99.7			—			—			122.7
	Total current liabilities	32			222.9			0.2			—			255.1
Long-term liabilities:
Long-term debt, less current portion	2,012.80			—			—			—			2,012.80
Other long-term liabilities	1.6			29.6			—			—			31.2
Partners' capital	4,125.70			6,001.50			123.5			(6,125.0		)	4,125.70
Interest of non-controlling partners in subsidiaries	171.7			—			171.7			(171.7		)	171.7
Total partners' capital	4,297.40			6,001.50			295.2			(6,296.7		)	4,297.40
Total liabilities and partners' capital	$	6,343.80		$	6,254.00		$	295.4		$	(6,296.7	)	$	6,596.50
Consolidating Statements of Operations
	Condensed Consolidating Statements of Operations
	Three Months Ended March 31, 2015
	(in millions)
		Parent			Guarantor			Non-			Eliminations			Consolidated
					Subsidiaries			Guarantor
								Subsidiaries
	Revenues	$	—		$	455.1		$	—		$	—		$	455.1
	Costs of product/services sold	—			286.6			—			—			286.6
	Expenses:
	Operations and maintenance	—			35.1			—			—			35.1
	General and administrative	13.4			10.8			—			—			24.2
	Depreciation, amortization and accretion	0.2			59.7			—			—			59.9
		13.6			105.6			—			—			119.2
	Other operating income (expense):
	Loss on long-lived assets, net	—			(0.8		)	—			—			(0.8		)
	Operating income	(13.6		)	62.1			—			—			48.5
	Earnings from unconsolidated affiliates, net	—			—			3.4			—			3.4
	Interest and debt expense, net	(29.9		)	—			—			—			(29.9		)
	Equity in net income (loss) of subsidiary	65.2			—			—			(65.2		)	—
	Income (loss) before income taxes	21.7			62.1			3.4			(65.2		)	22
	Provision for income taxes	—			0.3			—			—			0.3
	Net income (loss)	21.7			61.8			3.4			(65.2		)	21.7
	Net income attributable to non-controlling partners	—			—			(5.6		)	—			(5.6		)
	Net income (loss) attributable to Crestwood Midstream Partners LP	21.7			61.8			(2.2		)	(65.2		)	16.1
	Net income attributable to Class A preferred units	(9.2		)	—			—			—			(9.2		)
	Net income (loss) attributable to partners	$	12.5		$	61.8		$	(2.2	)	$	(65.2	)	$	6.9
Consolidating Statement of Cash Flows
	Condensed Consolidating Statements of Cash Flows
	Three Months Ended March 31, 2015
	(in millions)
		Parent			Guarantor			Non-			Eliminations			Consolidated
					Subsidiaries			Guarantor
								Subsidiaries
	Cash flows from operating activities:	$	(54.8	)	$	131.8		$	—		$	—		$	77
	Cash flows from investing activities:
	Purchases of property, plant and equipment	(0.1		)	(43.2		)	—			—			(43.3		)
	Investment in unconsolidated affiliates	—			—			(17.9		)	—			(17.9		)
	Proceeds from sale of assets	—			0.3			—			—			0.3
	Capital contribution to consolidated affiliates	(17.9		)	—			—			17.9			—
	Net cash provided by (used in) investing activities	(18.0		)	(42.9		)	(17.9		)	17.9			(60.9		)
	Cash flows from financing activities:
	Proceeds from the issuance of long-term debt	1,114.60			—			—			—			1,114.60
	Principal payments on long-term debt	(970.0		)	—			—			—			(970.0		)
	Payments on capital leases	(0.5		)	(0.2		)	—			—			(0.7		)
	Payments for debt-related deferred costs	(11.1		)	—			—			—			(11.1		)
	Distributions paid	(84.8		)	—			—			—			(84.8		)
	Contributions from parent	—			—			17.9			(17.9		)	—
	Taxes paid for unit-based compensation vesting	—			(1.7		)	—			—			(1.7		)
	Change in intercompany balances	24.8			(24.8		)	—			—			—
	Other	(0.2		)	—			—			—			(0.2		)
	Net cash provided by (used in) financing activities	72.8			(26.7		)	17.9			(17.9		)	46.1
	Net change in cash	—			62.2			—			—			62.2
	Cash at beginning of period	—			4.6			—			—			4.6
	Cash at end of period	$	—		$	66.8		$	—		$	—		$	66.8

Business_Description_Details

Business Description (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	5-May-15
	segment
Partnership Organization And Basis Of Presentation [Line Items]
Number of operating segments	3
CEQP
Partnership Organization And Basis Of Presentation [Line Items]
Managing member or general partner ownership interest	4.00%
Parent
Partnership Organization And Basis Of Presentation [Line Items]
Percentage of distribution entitled to receive	50.00%
First Reserve
Partnership Organization And Basis Of Presentation [Line Items]
Managing member or general partner ownership interest	11.00%
Distribution Rights
Partnership Organization And Basis Of Presentation [Line Items]
Distribution declared per limited partner unit	0.37
Distribution Rights | CEQP
Partnership Organization And Basis Of Presentation [Line Items]
Percentage of distribution entitled to receive	100.00%
Subsequent event
Partnership Organization And Basis Of Presentation [Line Items]
Equity interest issued or issuable, conversion ratio		2.75

Basis_of_Presentation_and_Summ2

Basis of Presentation and Summary of Significant Accounting Policies (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2014
Accounting Policies [Abstract]
Reimbursements of property, plant and equipment	$9.60

Acquisitions_Details

Acquisitions (Details) (USD $)	0 Months Ended
In Millions, unless otherwise specified	Mar. 21, 2014	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
	double_bottom_body_tanks
	trailer_tanks
	bbl
	tractor
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Goodwill		$1,632.60	$1,632.60	$1,689.30
Red Rock Transportation, Inc
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Consideration transferred	13.8
Cash paid	12.1
Liabilities incurred	1.8
Trailer Tanks, Number	44
Crude Hauling Capacity	28,000
Property, plant and equipment	10.6
Goodwill	3.2
NGL and Crude Services Operations
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Net [Abstract]
Goodwill		$825.20		$861.10

Certain_Balance_Sheet_Informat2

Certain Balance Sheet Information (Property Plant and Equipment) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Property, Plant and Equipment [Line Items]
Property, plant and equipment (Note 4)	$3,897	$3,883.50
Less: accumulated depreciation and depletion	391.6	365.4
Property, plant and equipment, net	3,505.40	3,518.10
Capital lease assets	2.6	2.8
Gathering systems and pipelines
Property, Plant and Equipment [Line Items]
Property, plant and equipment (Note 4)	1,281.20	1,276.60
Facilities and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment (Note 4)	1,458	1,468.80
Buildings, land, rights-of-way, storage contracts and easements
Property, Plant and Equipment [Line Items]
Property, plant and equipment (Note 4)	808.1	806.4
Vehicles
Property, Plant and Equipment [Line Items]
Property, plant and equipment (Note 4)	14.1	13.6
Construction in process
Property, Plant and Equipment [Line Items]
Property, plant and equipment (Note 4)	171.2	153.7
Base gas
Property, Plant and Equipment [Line Items]
Property, plant and equipment (Note 4)	37.5	37.5
Salt deposits
Property, Plant and Equipment [Line Items]
Property, plant and equipment (Note 4)	120.5	120.5
Office furniture and fixtures
Property, Plant and Equipment [Line Items]
Property, plant and equipment (Note 4)	$6.40	$6.40

Certain_Balance_Sheet_Informat3

Certain Balance Sheet Information (Intangible Assets) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	$1,020.20	$1,013.20
Less: accumulated amortization	155.5	137
Total intangible assets, net	864.7	876.2
Customer accounts
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	483.2	483.2
Covenants not to compete
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	5.6	5.6
Gas gathering, compression and processing contracts
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	427.3	431.4
Acquired storage contracts
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	29	29
Trademarks
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	9.7	9.7
Deferred financing costs
Finite-Lived Intangible Assets [Line Items]
Intangible assets, Gross	$65.40	$54.30

Certain_Balance_Sheet_Informat4

Certain Balance Sheet Information (Accrued Expenses and Other Liabilities) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Payables and Accruals [Abstract]
Accrued expenses	$17.90	$23.70
Accrued property taxes	3.9	2.1
Accrued product purchases payable	0.4	0.7
Tax payable	0	0.4
Interest payable	13.5	22
Accrued additions to property, plant and equipment	9.1	20
Commitments and contingent liabilities (Note 10)	0	40
Capital leases	0.9	1.3
Deferred revenue	11.3	11.6
Other	0	0.2
Total accrued expenses and other liabilities	$57	$122

Investments_in_Unconsolidated_2

Investments in Unconsolidated Affiliates (Net Investments In and Earnings (Loss) from Unconsolidated Affiliates) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Investment	$316.60		$295.10
Earnings from unconsolidated affiliates, net	3.4	-0.1
Jackalope Gas Gathering Services, LLC
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	50.00%
Investment	244.2		232.9
Earnings from unconsolidated affiliates, net	2.5	0.3
Difference between carrying amount and underlying equity	52.9
Amortization	0.8	0.8
Tres Palacios Holdings LLC
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	50.01%
Investment	42.8		36
Earnings from unconsolidated affiliates, net	0.9	0
Difference between carrying amount and underlying equity	30
Amortization	0.3
PRBIC
Schedule of Equity Method Investments [Line Items]
Ownership Percentage	50.01%
Investment	29.6		26.2
Earnings from unconsolidated affiliates, net	$0	($0.40)

Investments_in_Unconsolidated_3

Investments in Unconsolidated Affiliates (Narrative) (Details) (USD $)	3 Months Ended		1 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Apr. 30, 2015
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments	$17.90	$19.80
Jackalope Gas Gathering Services, LLC
Schedule of Equity Method Investments [Line Items]
Proceeds from equity method investment	0	0
Tres Palacios Holdings LLC
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments	5.7
PRBIC
Schedule of Equity Method Investments [Line Items]
Proceeds from equity method investment	0.3	0
Payments to acquire equity method investments	3.7	2.5
Crestwood Niobrara LLC | Jackalope Gas Gathering Services, LLC
Schedule of Equity Method Investments [Line Items]
Payments to acquire equity method investments	8.8	17.3
Subsequent event | Jackalope Gas Gathering Services, LLC
Schedule of Equity Method Investments [Line Items]
Proceeds from equity method investment			4.5
Subsequent event | Tres Palacios Holdings LLC
Schedule of Equity Method Investments [Line Items]
Proceeds from equity method investment			$2.10

Financial_Instruments_Schedule

Financial Instruments (Schedule of Carrying Values and Estimated Fair Values of Senior Notes) (Details) (Unsecured Debt, USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Carrying Amount | 2019 senior unsecured notes
Debt Instrument [Line Items]
Senior notes	$350.90	$351
Carrying Amount | 2020 senior unsecured notes
Debt Instrument [Line Items]
Senior notes	503.8	504
Carrying Amount | 2022 senior unsecured notes
Debt Instrument [Line Items]
Senior notes	600	600
Carrying Amount | 2023 Senior unsecured notes
Debt Instrument [Line Items]
Senior notes	700	0
Fair Value | 2019 senior unsecured notes
Debt Instrument [Line Items]
Fair value of senior notes	363.6	360.5
Fair Value | 2020 senior unsecured notes
Debt Instrument [Line Items]
Fair value of senior notes	500.3	481.6
Fair Value | 2022 senior unsecured notes
Debt Instrument [Line Items]
Fair value of senior notes	607.5	568.5
Fair Value | 2023 Senior unsecured notes
Debt Instrument [Line Items]
Fair value of senior notes	$710.50	$0

Financial_Instruments_Debt_Det

Financial Instruments (Debt) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Debt Instrument [Line Items]
Total debt	$2,157.80	$2,013.50
Less: current portion	36.1	0.7
Total long-term debt	2,121.70	2,012.80
Other
Debt Instrument [Line Items]
Other	3.1	3.5
Senior Notes | 2019 Senior Notes
Debt Instrument [Line Items]
Senior notes	350	350
Premium on senior notes	0.9	1
Senior Notes | 2020 Senior Notes
Debt Instrument [Line Items]
Senior notes	500	500
Fair value adjustment of senior notes	3.8	4
Senior Notes | 2022 Senior Notes
Debt Instrument [Line Items]
Senior notes	600	600
Senior Notes | 2023 Senior unsecured notes
Debt Instrument [Line Items]
Senior notes	700	0
Revolver | Crestwood Midstream Revolver
Debt Instrument [Line Items]
Outstanding balance on the credit facility	$0	$555

Financial_Instruments_Narrativ

Financial Instruments (Narrative) (Details) (USD $)	3 Months Ended	0 Months Ended
	Mar. 31, 2015	Dec. 03, 2014	Apr. 08, 2015	Dec. 31, 2014
Crestwood Midstream Revolver
Debt Instrument [Line Items]
Current debt to EBITDA ratio	4.58
Consolidated EBITDA to interest expense ratio	4.15
Crestwood Midstream Revolver | Revolver
Debt Instrument [Line Items]
Term of debt instrument	5 years
Line of credit, maximum capacity	1,000,000,000
Letters of credit outstanding	5,600,000			15,100,000
Remaining borrowing capacity	429,100,000
Weighted average interest rate				2.86%
Maximum leverage ratio	5
Consolidated Leverage Ratio, Maximum, Post Acquisitions	5.5	5.5
Minimum interest coverage ratio	2.5
Crestwood Midstream Revolver | Standby Letters of Credit
Debt Instrument [Line Items]
Line of credit, maximum capacity	250,000,000
Crestwood Midstream Revolver | Swing Line Loans
Debt Instrument [Line Items]
Line of credit, maximum capacity	25,000,000
2019 Senior Notes | Senior Notes
Debt Instrument [Line Items]
Face amount of debt	350,000,000
Interest rate on debt	7.75%
Senior notes	350,000,000			350,000,000
2020 Senior Notes | Senior Notes
Debt Instrument [Line Items]
Face amount of debt	500,000,000
Interest rate on debt	6.00%
Senior notes	500,000,000			500,000,000
2022 Senior Notes | Senior Notes
Debt Instrument [Line Items]
Face amount of debt	600,000,000
Interest rate on debt	6.13%
Senior notes	600,000,000			600,000,000
2023 Senior unsecured notes | Senior Notes
Debt Instrument [Line Items]
Interest rate on debt	6.25%
Proceeds from issuance of debt	688,900,000
Senior notes	700,000,000			0
Minimum | Crestwood Midstream Revolver | Revolver
Debt Instrument [Line Items]
Interest rate at the end of the period				2.66%
Maximum | Crestwood Midstream Revolver | Revolver
Debt Instrument [Line Items]
Interest rate at the end of the period				4.75%
Subsequent event | 2019 Senior Notes | Senior Notes
Debt Instrument [Line Items]
Early repayment of senior debt			364,100,000
Interest paid			500,000
Call premium on debt redemption			13,600,000
Subsequent event | 2023 Senior unsecured notes | Senior Notes
Debt Instrument [Line Items]
Proceeds from issuance of debt			$315,000,000
Tres Palacios Holdings LLC
Debt Instrument [Line Items]
Ownership Percentage	50.01%

Earnings_Per_Limited_Partner_U2

Earnings Per Limited Partner Unit (Allocation of Net Income to General and Limited Partners) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Earnings Per Share [Abstract]
Net income attributable to CMLP	$16.10	$2.40
Class A preferred units’ interest in net income attributable to CMLP	-9.2	0
General partner’s incentive distributions	-7.5	-7.5
Limited partners’ interest in net income (loss) attributable to CMLP after incentive distributions	($0.60)	($5.10)

Earnings_Per_Limited_Partner_U3

Earnings Per Limited Partner Unit (Schedule of Reconciliation of Earnings Per Share) (Details) (USD $)	3 Months Ended
In Millions, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Earnings Per Share [Abstract]
Limited partners’ interest in net income (loss) attributable to CMLP after incentive distributions	($0.60)	($5.10)
Basic (units)	188,290,000	187,840,000
Incremental Common Shares Attributable to Share-based Payment Arrangements	0	0
Diluted (units)	188,290,000	187,840,000
Basic, in dollars per unit	$0	($0.03)
Diluted, in dollars per unit	$0	($0.03)

Earnings_Per_Limited_Partner_U4

Earnings Per Limited Partner Unit (Narrative) (Details)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Crestwood Niobrara LLC
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	12,325,740	4,922,372
Preferred Units
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount	18,332,193
Distribution Rights | CEQP
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Percentage of distribution entitled to receive	100.00%

Partners_Capital_Narrative_Det

Partners' Capital (Narrative) (Details) (USD $)	0 Months Ended				3 Months Ended		0 Months Ended
	Feb. 13, 2015	Jul. 10, 2014	Jun. 17, 2014	Feb. 14, 2014	Mar. 31, 2015	Mar. 31, 2014	Sep. 22, 2014	Apr. 23, 2015	Apr. 30, 2015
Distribution Made to Limited Partner [Line Items]
Issuance of Class A preferred units		$300,000,000	$500,000,000
Offering Costs, Partnership Interests		0.02
Maximum Period For Distribution Of Available Cash					45 days
Distributions to general partner					-10,500,000	-10,500,000
Per unit rate, in dollars per unit	$0.41			$0.41
Net Income (Loss) Attributable to Noncontrolling Interest					5,600,000	3,100,000
Distribution Made to Member or Limited Partner, Cash Distributions Paid	74,300,000			74,100,000	74,300,000	74,100,000
Distribution Made to Limited Partner, Unit Distribution	414,325
Crestwood Niobrara LLC | Preferred Units
Distribution Made to Limited Partner [Line Items]
Distribution Made to Limited Partner, Unit Distribution					3,680,570	2,210,294
Jackalope Gas Gathering Services, LLC | Crestwood Niobrara LLC
Distribution Made to Limited Partner [Line Items]
Issuance of preferred equity of subsidiary						12,300,000
Preferred Partner
Distribution Made to Limited Partner [Line Items]
Partners' Capital, Distribution Amount Per Share					$0.58
Partners' Capital Account, Private Placement of Units			$25.10
Partners' Capital, Contingent Distribution Amount Per Share					$0.71
Partner's Capital, Unpaid Distribution, Accrual Percentage			2.81%
Preferred Partner | Preferred Units, Class A
Distribution Made to Limited Partner [Line Items]
Partners' Capital Account, Term to Convert Cash Distributions to Stock Distributions					36 months
Class A Purchasers | Preferred Units, Class A
Distribution Made to Limited Partner [Line Items]
Partners' Capital Account, Private Placement of Units							$25.10
Limited Partner
Distribution Made to Limited Partner [Line Items]
Distributions to general partner					10,500,000
Subsequent event
Distribution Made to Limited Partner [Line Items]
Distribution Made to Limited Partner, Unit Distribution								423,903
Subsequent event | Crestwood Niobrara LLC | Cash distribution
Distribution Made to Limited Partner [Line Items]
Distribution Made to Member or Limited Partner, Cash Distributions Paid									$3,800,000
Dividend Paid | Subsequent event | Cash distribution
Distribution Made to Limited Partner [Line Items]
Distribution declared per limited partner unit								0.41

Partners_Capital_Schedule_of_P

Partners' Capital (Schedule of Partnership Distributions) (Details) (USD $)	0 Months Ended				3 Months Ended		0 Months Ended
In Millions, except Per Share data, unless otherwise specified	Feb. 13, 2015	Feb. 06, 2015	Feb. 14, 2014	Feb. 07, 2014	Mar. 31, 2015	Mar. 31, 2014	Apr. 23, 2015
Limited Partners' Capital Account [Line Items]
Distribution Made to Limited Partner, Date of Record		6-Feb-15		7-Feb-14
Distribution Made to Limited Partner, Distribution Date	13-Feb-15		14-Feb-14
Distribution Made to Limited Partner, Distributions Paid, Per Unit	$0.41		$0.41
Distribution Made to Member or Limited Partner, Cash Distributions Paid	$74.30		$74.10		$74.30	$74.10
Dividend Paid | Cash distribution | Subsequent event
Disclosure Partners Capital Summary Of Quarterly Distributions Of Available Cash [Abstract]
Distribution declared per limited partner unit							$0.41

Equity_Plans_Narrative_Details

Equity Plans (Narrative) (Details) (USD $)	3 Months Ended		1 Months Ended
In Millions, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Apr. 30, 2015	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unit-based compensation charges	$5.20	$4.60
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent	10.00%
Defined Contribution Plan, Employer Matching Contribution, Percent of Match	10.00%
Defined Contribution Plan, Maximum Purchasable Units	200,000
Unit Purchase Plan, Shares Purchased Under Plan	2,011
Crestwood LTIP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized, Period for Recognition	3 years
Unit-based compensation charges	3	2.9
Shares Paid for Tax Withholding for Share Based Compensation	134,591	7,456
Crestwood LTIP | CMLP
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Allocated Share-based Compensation Expense	2.2	1.7
Crestwood LTIP | Restricted units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	37,997
Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized	15.7			9.5
Share-based Compensation Arrangement, Equity Instruments Other than Options, Grants in Period, Fair Value	8.2
Common Stock, Capital Shares Reserved for Future Issuance	17,199,153
Crestwood LTIP | Phantom Units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement, Equity Instruments Other than Options, Grants in Period, Fair Value	$2.60
Employee Severance | Crestwood LTIP | Restricted units
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period	21,583
Subsequent event
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unit Purchase Plan, Shares Purchased Under Plan			3,841

Equity_Plans_Restricted_Unit_A

Equity Plans (Restricted Unit Activity) (Details) (Crestwood LTIP, USD $)	3 Months Ended
	Mar. 31, 2015
Restricted units
Units
Unvested - January 1, 2015	834,796
Vested - restricted units	-424,653
Granted - restricted units	512,404
Forfeited(1)	-37,997
Unvested - March 31, 2015	1,045,589
Weighted-Average Grant Date Fair Value
Unvested - January 1, 2015	$23.18
Vested - restricted units	$23.11
Granted - restricted units	$16.01
Forfeited(1)	$20.93
Unvested - March 31, 2015	$18.68
Phantom Units
Units
Granted - restricted units	161,039
Weighted-Average Grant Date Fair Value
Granted - restricted units	$16.02

Commitments_and_Contingencies_

Commitments and Contingencies (Details) (USD $)	12 Months Ended	1 Months Ended
In Millions, except Share data, unless otherwise specified	Dec. 31, 2014	Mar. 31, 2014	Mar. 31, 2015	Nov. 08, 2013
		defendant		bbl
				people
Schedule Of Commitments And Contingencies [Line Items]
Escrow deposit of common units	3,309,797
Loss contingency accrual, less than	$0.10		$0.10
Antero
Schedule Of Commitments And Contingencies [Line Items]
Contingent consideration liability			$40
Arrow Acquisition Class Action Lawsuit
Schedule Of Commitments And Contingencies [Line Items]
Barrels of oil equivalents spilled				50,000
Loss of life, number				47
Number of defendants		53

Commitments_and_Contingencies_1

Commitments and Contingencies (Environmental Compliance) (Details) (Fort Berthold Indian Reservation, USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	6-May-15
	Release		bbl
	bbl
Site Contingency [Line Items]
Number of releases of produced water	3
Number of barrels of produced water	28,000
Accrual for environmental loss contingencies	$0.30	$1.10
Low estimate of environmental liability	0.3
High estimate of environmental liability	$0.80
Subsequent event
Site Contingency [Line Items]
Number of barrels of produced water			8,000

Related_Party_Transactions_Det

Related Party Transactions (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Disclosure Related Party Transaction Additional Information [Abstract]
Gathering and processing revenues	$4.60	$4.20
Reimbursement of operations and maintenance expenses	0.9	0
Related Party Transaction, Due from (to) Related Party [Abstract]
Accounts receivable	1.1		0.3
Accounts payable	5.5		6.3
CEQP
Disclosure Related Party Transaction Additional Information [Abstract]
Gathering and processing revenues	1.2	0.9
NGL and crude services revenues	3.4	3.3
Gathering and processing costs of product/services sold (1)	8.3	11
General and administrative expenses (2)	17.4	19.6
Affiliates
Related Party Transaction, Due from (to) Related Party [Abstract]
Accounts receivable	1.1		0.3
Accounts payable	$5.50		$6.30

Segments_Narrative_Details

Segments (Narrative) (Details)	3 Months Ended
	Mar. 31, 2015
	segment
Segment Reporting Information [Line Items]
Number of operating segments	3

Segments_Reconciliation_of_Net

Segments (Reconciliation of Net Income to EBITDA) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Segment Reporting [Abstract]
Net income	$21.70	$5.50
Interest and debt expense, net	29.9	28.1
Provision for income taxes	0.3	0.7
Depreciation, amortization and accretion	59.9	50.8
EBITDA	$111.80	$85.10

Segments_Schedule_of_Reportabl

Segments (Schedule of Reportable Segment Data) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Segment Reporting Information [Line Items]
Revenues	$455.10	$537
Costs of product/services sold	286.6	398.1
Operations and maintenance	35.1	28
General and administrative expense	24.2	24.1
Gain (loss) on long-lived assets, net	-0.8	0.5
Loss on contingent consideration	0	-2.1
Earnings from unconsolidated affiliates, net	3.4	-0.1
EBITDA	111.8	85.1
Goodwill	1,632.60	1,689.30	1,632.60
Total assets	6,612.70	6,491.40	6,596.50
Purchases of property, plant and equipment	43.3	77.3
Gathering and Processing
Segment Reporting Information [Line Items]
Revenues	78.5	79.5
Costs of product/services sold	12.7	18.7
Operations and maintenance	14.9	13.4
General and administrative expense	0	0
Gain (loss) on long-lived assets, net	-0.3	0.5
Loss on contingent consideration		-2.1
Earnings from unconsolidated affiliates, net	2.5	0.3
EBITDA	53.1	46.1
Goodwill	81.1	99.6
Total assets	1,969.60	1,881.60
Purchases of property, plant and equipment	11.4	46.3
Storage and Transportation
Segment Reporting Information [Line Items]
Revenues	45.7	44.3
Costs of product/services sold	3.3	3.2
Operations and maintenance	4.3	4.3
General and administrative expense	0	0
Gain (loss) on long-lived assets, net	-0.5	0
Loss on contingent consideration		0
Earnings from unconsolidated affiliates, net	0.9	0
EBITDA	38.5	36.8
Goodwill	726.3	728.6
Total assets	1,976.10	1,975.50
Purchases of property, plant and equipment	2.7	1.2
NGL and Crude Services
Segment Reporting Information [Line Items]
Revenues	330.9	413.2
Costs of product/services sold	270.6	376.2
Operations and maintenance	15.9	10.3
General and administrative expense	0	0
Gain (loss) on long-lived assets, net	0	0
Loss on contingent consideration		0
Earnings from unconsolidated affiliates, net	0	-0.4
EBITDA	44.4	26.3
Goodwill	825.2	861.1
Total assets	2,514	2,478
Purchases of property, plant and equipment	29.1	28.9
Corporate
Segment Reporting Information [Line Items]
Revenues	0	0
Costs of product/services sold	0	0
Operations and maintenance	0	0
General and administrative expense	24.2	24.1
Gain (loss) on long-lived assets, net	0	0
Loss on contingent consideration		0
Earnings from unconsolidated affiliates, net	0	0
EBITDA	-24.2	-24.1
Goodwill	0	0
Total assets	153	156.3
Purchases of property, plant and equipment	$0.10	$0.90

Condensed_Consolidating_Financ2

Condensed Consolidating Financial Information (Narrative) (Details)	3 Months Ended
	Mar. 31, 2015
Condensed Financial Information of Parent Company Only Disclosure [Abstract]
Ownership interest	100.00%

Condensed_Consolidating_Financ3

Condensed Consolidating Financial Information (Statement of Operations Adjustments to Prior Periods) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Condensed Financial Statements, Captions [Line Items]
General and administrative expense	$24.20	$24.10
Operating income	48.5	34.4
Equity in net income (loss) of subsidiary	0	0
Income before income taxes	22	6.2
Net income	21.7	5.5
Net income attributable to Crestwood Midstream Partners LP	16.1	2.4
Parent
Condensed Financial Statements, Captions [Line Items]
General and administrative expense	13.4	17
Operating income	-13.6	-17.2
Equity in net income (loss) of subsidiary	65.2	50.8
Income before income taxes	21.7	5.5
Net income	21.7	5.5
Net income attributable to Crestwood Midstream Partners LP	21.7	5.5
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
General and administrative expense	10.8	7.1
Operating income	62.1	51.6
Equity in net income (loss) of subsidiary	0	0
Income before income taxes	62.1	51.6
Net income	61.8	50.9
Net income attributable to Crestwood Midstream Partners LP	61.8	50.9
Consolidation, Eliminations
Condensed Financial Statements, Captions [Line Items]
General and administrative expense	0	0
Operating income	0	0
Equity in net income (loss) of subsidiary	-65.2	-50.8
Income before income taxes	-65.2	-50.8
Net income	-65.2	-50.8
Net income attributable to Crestwood Midstream Partners LP	-65.2	-50.8
Scenario, Previously Reported | Parent
Condensed Financial Statements, Captions [Line Items]
General and administrative expense		-2.1
Operating income		1.9
Equity in net income (loss) of subsidiary		31.7
Income before income taxes		5.5
Net income		5.5
Net income attributable to Crestwood Midstream Partners LP		5.5
Scenario, Previously Reported | Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
General and administrative expense		26.2
Operating income		32.5
Equity in net income (loss) of subsidiary		0
Income before income taxes		32.5
Net income		31.8
Net income attributable to Crestwood Midstream Partners LP		31.8
Scenario, Previously Reported | Consolidation, Eliminations
Condensed Financial Statements, Captions [Line Items]
General and administrative expense		0
Operating income		0
Equity in net income (loss) of subsidiary		-31.7
Income before income taxes		-31.7
Net income		-31.7
Net income attributable to Crestwood Midstream Partners LP		($31.70)

Condensed_Consolidating_Financ4

Condensed Consolidating Financial Information (Cash Flow Adjustments to Prior Periods) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014	Dec. 31, 2012
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	$77	$67.70
Payments to Acquire Businesses, Net of Cash Acquired	0	12.1
Purchases of property, plant and equipment	-43.3	-77.3
Investment in unconsolidated affiliates	-17.9	-19.8
Proceeds from sale of assets	0.3	0
Capital contribution from consolidated affiliate	0	0
Net Cash Provided by (Used in) Investing Activities	-60.9	-109.2
Proceeds from the issuance of long-term debt	1,114.60	306
Principal payments on long-term debt	-970	-188.8
Repayments of Long-term Capital Lease Obligations	0.7	1.1
Distributions paid	-84.8	-84.6
Contributions from general partner	0	0
Net proceeds from issuance of preferred equity of subsidiary	0	12.3
Taxes paid for unit-based compensation vesting	-1.7	0
Net change in payables to affiliate	0	0
Other	-0.2	0
Net Cash Provided by (Used in) Financing Activities	46.1	43.8
Cash and Cash Equivalents, Period Increase (Decrease)	62.2	2.3
Cash	66.8	5	4.6	2.7
Parent
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	-54.8	-39.6
Payments to Acquire Businesses, Net of Cash Acquired		0
Purchases of property, plant and equipment	-0.1	-0.9
Investment in unconsolidated affiliates	0	0
Proceeds from sale of assets	0
Capital contribution from consolidated affiliate	-17.9	-6.5
Payments for (Proceeds from) Other Investing Activities		0
Net Cash Provided by (Used in) Investing Activities	-18	-7.4
Proceeds from the issuance of long-term debt	1,114.60	306
Principal payments on long-term debt	-970	-188.8
Repayments of Long-term Capital Lease Obligations	0.5	0.3
Distributions paid	-84.8	-84.6
Contributions from general partner	0	0
Net proceeds from issuance of preferred equity of subsidiary		0
Taxes paid for unit-based compensation vesting	0
Net change in payables to affiliate	24.8	15.4
Other	-0.2
Net Cash Provided by (Used in) Financing Activities	72.8	47.7
Cash and Cash Equivalents, Period Increase (Decrease)	0	0.7
Cash	0	0.8	0	0.1
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	131.8	107.3
Payments to Acquire Businesses, Net of Cash Acquired		12.1
Purchases of property, plant and equipment	-43.2	-76.4
Investment in unconsolidated affiliates	0	0
Proceeds from sale of assets	0.3
Capital contribution from consolidated affiliate	0	0
Payments for (Proceeds from) Other Investing Activities		0
Net Cash Provided by (Used in) Investing Activities	-42.9	-88.5
Proceeds from the issuance of long-term debt	0	0
Principal payments on long-term debt	0	0
Repayments of Long-term Capital Lease Obligations	0.2	0.8
Distributions paid	0	0
Contributions from general partner	0	0
Net proceeds from issuance of preferred equity of subsidiary		0
Taxes paid for unit-based compensation vesting	-1.7
Net change in payables to affiliate	-24.8	-15.4
Other	0
Net Cash Provided by (Used in) Financing Activities	-26.7	-16.2
Cash and Cash Equivalents, Period Increase (Decrease)	62.2	2.6
Cash	66.8	4.2	4.6	1.6
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	0	0
Payments to Acquire Businesses, Net of Cash Acquired		0
Purchases of property, plant and equipment	0	0
Investment in unconsolidated affiliates	-17.9	-19.8
Proceeds from sale of assets	0
Capital contribution from consolidated affiliate	0	0
Payments for (Proceeds from) Other Investing Activities		0
Net Cash Provided by (Used in) Investing Activities	-17.9	-19.8
Proceeds from the issuance of long-term debt	0	0
Principal payments on long-term debt	0	0
Repayments of Long-term Capital Lease Obligations	0	0
Distributions paid	0	0
Contributions from general partner	17.9	6.5
Net proceeds from issuance of preferred equity of subsidiary		12.3
Taxes paid for unit-based compensation vesting	0
Net change in payables to affiliate	0	0
Other	0
Net Cash Provided by (Used in) Financing Activities	17.9	18.8
Cash and Cash Equivalents, Period Increase (Decrease)	0	-1
Cash	0	0	0	1
Consolidation, Eliminations
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	0	0
Payments to Acquire Businesses, Net of Cash Acquired		0
Purchases of property, plant and equipment	0	0
Investment in unconsolidated affiliates	0	0
Proceeds from sale of assets	0
Capital contribution from consolidated affiliate	17.9	6.5
Payments for (Proceeds from) Other Investing Activities		0
Net Cash Provided by (Used in) Investing Activities	17.9	6.5
Proceeds from the issuance of long-term debt	0	0
Principal payments on long-term debt	0	0
Repayments of Long-term Capital Lease Obligations	0	0
Distributions paid	0	0
Contributions from general partner	-17.9	-6.5
Net proceeds from issuance of preferred equity of subsidiary		0
Taxes paid for unit-based compensation vesting	0
Net change in payables to affiliate	0	0
Other	0
Net Cash Provided by (Used in) Financing Activities	-17.9	-6.5
Cash and Cash Equivalents, Period Increase (Decrease)	0	0
Cash	0	0	0	0
Scenario, Previously Reported | Parent
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities		5.8
Investment in unconsolidated affiliates		0
Capital contribution from consolidated affiliate		-4
Payments for (Proceeds from) Other Investing Activities		-2.4
Net Cash Provided by (Used in) Investing Activities		-7.3
Proceeds from the issuance of long-term debt		2.5
Principal payments on long-term debt		0
Distributions paid		0
Contributions from general partner		0
Net change in payables to affiliate		0
Net Cash Provided by (Used in) Financing Activities		2.2
Scenario, Previously Reported | Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities		52.3
Investment in unconsolidated affiliates		-2.5
Capital contribution from consolidated affiliate		0
Payments for (Proceeds from) Other Investing Activities		0
Net Cash Provided by (Used in) Investing Activities		-81.4
Proceeds from the issuance of long-term debt		303.5
Principal payments on long-term debt		-188.8
Distributions paid		-84.6
Contributions from general partner		0
Net change in payables to affiliate		2.4
Net Cash Provided by (Used in) Financing Activities		31.7
Scenario, Previously Reported | Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities		0
Investment in unconsolidated affiliates		-17.3
Capital contribution from consolidated affiliate		0
Payments for (Proceeds from) Other Investing Activities		0
Net Cash Provided by (Used in) Investing Activities		-17.3
Proceeds from the issuance of long-term debt		0
Principal payments on long-term debt		0
Distributions paid		0
Contributions from general partner		4
Net change in payables to affiliate		0
Net Cash Provided by (Used in) Financing Activities		16.3
Scenario, Previously Reported | Consolidation, Eliminations
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities		0
Investment in unconsolidated affiliates		0
Capital contribution from consolidated affiliate		4
Payments for (Proceeds from) Other Investing Activities		2.4
Net Cash Provided by (Used in) Investing Activities		6.4
Proceeds from the issuance of long-term debt		0
Principal payments on long-term debt		0
Distributions paid		0
Contributions from general partner		-4
Net change in payables to affiliate		-2.4
Net Cash Provided by (Used in) Financing Activities		($6.40)

Condensed_Consolidating_Financ5

Condensed Consolidating Financial Information (Condensed Consolidating Balance Sheet) (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2012
In Millions, unless otherwise specified
Condensed Financial Statements, Captions [Line Items]
Cash	$66.80	$4.60	$5	$2.70
Other Receivables	191.5	241.5
Accounts receivable	192.6	241.8
Accounts receivable, related party	1.1	0.3
Inventory	9.2	8
Prepaid expenses and other current assets	23.6	18.7
Total current assets	292.2	273.1
Property, plant and equipment, net	3,505.40	3,518.10
Goodwill and intangible assets, net	2,497.30	2,508.80
Investment in Consolidated Subsidiaries	0	0
Investment in unconsolidated affiliates (Note 5)	316.6	295.1
Other assets	1.2	1.4
Total assets	6,612.70	6,596.50	6,491.40
Accounts payable trade	123.1	126.1
Accounts payable - related party (Note 11)	5.5	6.3
Accounts payable	128.6	132.4
Other current liabilities	93.1	122.7
Total current liabilities	221.7	255.1
Long-term debt, less current portion (Note 6)	2,121.70	2,012.80
Other long-term liabilities	31.5	31.2
Partners' Capital	4,060.50	4,125.70
Interest of non-controlling partners in subsidiary	177.3	171.7
Total partners’ capital	4,237.80	4,297.40
Total liabilities and partners’ capital	6,612.70	6,596.50
Parent
Condensed Financial Statements, Captions [Line Items]
Cash	0	0	0.8	0.1
Other Receivables	0.9	1.2
Accounts receivable	0.9	1.2
Accounts receivable, related party	0	0
Inventory	0	0
Prepaid expenses and other current assets	0	0
Total current assets	0.9	1.2
Property, plant and equipment, net	7.3	7.9
Goodwill and intangible assets, net	47	38
Investment in Consolidated Subsidiaries	6,359.50	6,296.70
Investment in unconsolidated affiliates (Note 5)	0	0
Other assets	0	0
Total assets	6,414.70	6,343.80
Accounts payable trade	1.3	4.8
Accounts payable - related party (Note 11)	3.2	4.2
Accounts payable	4.5	9
Other current liabilities	49.5	23
Total current liabilities	54	32
Long-term debt, less current portion (Note 6)	2,121.70	2,012.80
Other long-term liabilities	1.2	1.6
Partners' Capital	4,060.50	4,125.70
Interest of non-controlling partners in subsidiary	177.3	171.7
Total partners’ capital	4,237.80	4,297.40
Total liabilities and partners’ capital	6,414.70	6,343.80
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash	66.8	4.6	4.2	1.6
Other Receivables	190.6	240.3
Accounts receivable	190.6	240.3
Accounts receivable, related party	0	0
Inventory	9.2	8
Prepaid expenses and other current assets	23.6	18.7
Total current assets	290.2	271.6
Property, plant and equipment, net	3,498.10	3,510.20
Goodwill and intangible assets, net	2,450.30	2,470.80
Investment in Consolidated Subsidiaries	0	0
Investment in unconsolidated affiliates (Note 5)	0	0
Other assets	1.2	1.4
Total assets	6,239.80	6,254
Accounts payable trade	121.8	121.3
Accounts payable - related party (Note 11)	1.3	1.9
Accounts payable	123.1	123.2
Other current liabilities	43.6	99.7
Total current liabilities	166.7	222.9
Long-term debt, less current portion (Note 6)	0	0
Other long-term liabilities	30.3	29.6
Partners' Capital	6,042.80	6,001.50
Interest of non-controlling partners in subsidiary	0	0
Total partners’ capital	6,042.80	6,001.50
Total liabilities and partners’ capital	6,239.80	6,254
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Cash	0	0	0	1
Other Receivables	0	0
Accounts receivable	1.1	0.3
Accounts receivable, related party	1.1	0.3
Inventory	0	0
Prepaid expenses and other current assets	0	0
Total current assets	1.1	0.3
Property, plant and equipment, net	0	0
Goodwill and intangible assets, net	0	0
Investment in Consolidated Subsidiaries	0	0
Investment in unconsolidated affiliates (Note 5)	316.6	295.1
Other assets	0	0
Total assets	317.7	295.4
Accounts payable trade	0	0
Accounts payable - related party (Note 11)	1	0.2
Accounts payable	1	0.2
Other current liabilities	0	0
Total current liabilities	1	0.2
Long-term debt, less current portion (Note 6)	0	0
Other long-term liabilities	0	0
Partners' Capital	139.4	123.5
Interest of non-controlling partners in subsidiary	177.3	171.7
Total partners’ capital	316.7	295.2
Total liabilities and partners’ capital	317.7	295.4
Consolidation, Eliminations
Condensed Financial Statements, Captions [Line Items]
Cash	0	0	0	0
Other Receivables	0	0
Accounts receivable	0	0
Accounts receivable, related party	0	0
Inventory	0	0
Prepaid expenses and other current assets	0	0
Total current assets	0	0
Property, plant and equipment, net	0	0
Goodwill and intangible assets, net	0	0
Investment in Consolidated Subsidiaries	-6,359.50	-6,296.70
Investment in unconsolidated affiliates (Note 5)	0	0
Other assets	0	0
Total assets	-6,359.50	-6,296.70
Accounts payable trade	0	0
Accounts payable - related party (Note 11)	0	0
Accounts payable	0	0
Other current liabilities	0	0
Total current liabilities	0	0
Long-term debt, less current portion (Note 6)	0	0
Other long-term liabilities	0	0
Partners' Capital	-6,182.20	-6,125
Interest of non-controlling partners in subsidiary	-177.3	-171.7
Total partners’ capital	-6,359.50	-6,296.70
Total liabilities and partners’ capital	($6,359.50)	($6,296.70)

Condensed_Consolidating_Financ6

Condensed Consolidating Financial Information (Condensed Consolidating Statement of Operations) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Revenues	$455.10	$537
Costs of product/services sold	286.6	398.1
Operations and maintenance	35.1	28
General and administrative expense	24.2	24.1
Depreciation, amortization and accretion	59.9	50.8
Total Expenses	119.2	102.9
Loss on long-lived assets, net	-0.8	0.5
Loss on contingent consideration	0	-2.1
Operating income	48.5	34.4
Earnings from unconsolidated affiliates, net	3.4	-0.1
Interest and debt expense, net	-29.9	-28.1
Equity in net income (loss) of subsidiary	0	0
Income (loss) before income taxes	22	6.2
Provision for income taxes	0.3	0.7
Net income	21.7	5.5
Net income attributable to non-controlling partners	-5.6	-3.1
Net income attributable to Crestwood Midstream Partners LP	16.1	2.4
Net income attributable to Class A preferred units	-9.2	0
Net income attributable to partners	6.9	2.4
Parent
Condensed Financial Statements, Captions [Line Items]
Revenues	0	0
Costs of product/services sold	0	0
Operations and maintenance	0	0
General and administrative expense	13.4	17
Depreciation, amortization and accretion	0.2	0.2
Total Expenses	13.6	17.2
Loss on long-lived assets, net	0	0
Loss on contingent consideration		0
Operating income	-13.6	-17.2
Earnings from unconsolidated affiliates, net	0	0
Interest and debt expense, net	-29.9	-28.1
Equity in net income (loss) of subsidiary	65.2	50.8
Income (loss) before income taxes	21.7	5.5
Provision for income taxes	0	0
Net income	21.7	5.5
Net income attributable to non-controlling partners	0	0
Net income attributable to Crestwood Midstream Partners LP	21.7	5.5
Net income attributable to Class A preferred units	-9.2
Net income attributable to partners	12.5
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Revenues	455.1	537
Costs of product/services sold	286.6	398.1
Operations and maintenance	35.1	28
General and administrative expense	10.8	7.1
Depreciation, amortization and accretion	59.7	50.6
Total Expenses	105.6	85.7
Loss on long-lived assets, net	-0.8	0.5
Loss on contingent consideration		-2.1
Operating income	62.1	51.6
Earnings from unconsolidated affiliates, net	0	0
Interest and debt expense, net	0	0
Equity in net income (loss) of subsidiary	0	0
Income (loss) before income taxes	62.1	51.6
Provision for income taxes	0.3	0.7
Net income	61.8	50.9
Net income attributable to non-controlling partners	0	0
Net income attributable to Crestwood Midstream Partners LP	61.8	50.9
Net income attributable to Class A preferred units	0
Net income attributable to partners	61.8
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Revenues	0	0
Costs of product/services sold	0	0
Operations and maintenance	0	0
General and administrative expense	0	0
Depreciation, amortization and accretion	0	0
Total Expenses	0	0
Loss on long-lived assets, net	0	0
Loss on contingent consideration		0
Operating income	0	0
Earnings from unconsolidated affiliates, net	3.4	-0.1
Interest and debt expense, net	0	0
Equity in net income (loss) of subsidiary	0	0
Income (loss) before income taxes	3.4	-0.1
Provision for income taxes	0	0
Net income	3.4	-0.1
Net income attributable to non-controlling partners	-5.6	-3.1
Net income attributable to Crestwood Midstream Partners LP	-2.2	-3.2
Net income attributable to Class A preferred units	0
Net income attributable to partners	-2.2
Consolidation, Eliminations
Condensed Financial Statements, Captions [Line Items]
Revenues	0	0
Costs of product/services sold	0	0
Operations and maintenance	0	0
General and administrative expense	0	0
Depreciation, amortization and accretion	0	0
Total Expenses	0	0
Loss on contingent consideration		0
Operating income	0	0
Earnings from unconsolidated affiliates, net	0	0
Interest and debt expense, net	0	0
Equity in net income (loss) of subsidiary	-65.2	-50.8
Income (loss) before income taxes	-65.2	-50.8
Provision for income taxes	0	0
Net income	-65.2	-50.8
Net income attributable to non-controlling partners	0	0
Net income attributable to Crestwood Midstream Partners LP	-65.2	-50.8
Net income attributable to Class A preferred units	0
Net income attributable to partners	($65.20)

Condensed_Consolidating_Financ7

Condensed Consolidating Financial Information (Condensed Consolidating Statements of Cash Flows) (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	$77	$67.70
Acquisitions, net of cash acquired	0	-12.1
Purchases of property, plant and equipment	-43.3	-77.3
Investment in unconsolidated affiliates	-17.9	-19.8
Capital contribution from consolidated affiliate	0	0
Proceeds from sale of assets	0.3	0
Net cash used in investing activities	-60.9	-109.2
Proceeds from the issuance of long-term debt	1,114.60	306
Principal payments on long-term debt	-970	-188.8
Distributions paid	-84.8	-84.6
Contributions from parent	0	0
Net proceeds from issuance of preferred equity of subsidiary	0	12.3
Payments on capital leases	-0.7	-1.1
Taxes paid for unit-based compensation vesting	-1.7	0
Payments of Debt Issuance Costs	11.1	0
Net change in payables to affiliate	0	0
Other	-0.2	0
Net cash provided by financing activities	46.1	43.8
Net change in cash	62.2	2.3
Cash at beginning of period	4.6
Cash at end of period	66.8	5
Parent
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	-54.8	-39.6
Acquisitions, net of cash acquired		0
Purchases of property, plant and equipment	-0.1	-0.9
Investment in unconsolidated affiliates	0	0
Capital contribution from consolidated affiliate	-17.9	-6.5
Proceeds from sale of assets	0
Net cash used in investing activities	-18	-7.4
Proceeds from the issuance of long-term debt	1,114.60	306
Principal payments on long-term debt	-970	-188.8
Distributions paid	-84.8	-84.6
Contributions from parent	0	0
Net proceeds from issuance of preferred equity of subsidiary		0
Payments on capital leases	-0.5	-0.3
Taxes paid for unit-based compensation vesting	0
Payments of Debt Issuance Costs	11.1
Net change in payables to affiliate	24.8	15.4
Other	-0.2
Net cash provided by financing activities	72.8	47.7
Net change in cash	0	0.7
Cash at beginning of period	0
Cash at end of period	0	0.8
Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	131.8	107.3
Acquisitions, net of cash acquired		-12.1
Purchases of property, plant and equipment	-43.2	-76.4
Investment in unconsolidated affiliates	0	0
Capital contribution from consolidated affiliate	0	0
Proceeds from sale of assets	0.3
Net cash used in investing activities	-42.9	-88.5
Proceeds from the issuance of long-term debt	0	0
Principal payments on long-term debt	0	0
Distributions paid	0	0
Contributions from parent	0	0
Net proceeds from issuance of preferred equity of subsidiary		0
Payments on capital leases	-0.2	-0.8
Taxes paid for unit-based compensation vesting	-1.7
Payments of Debt Issuance Costs	0
Net change in payables to affiliate	-24.8	-15.4
Other	0
Net cash provided by financing activities	-26.7	-16.2
Net change in cash	62.2	2.6
Cash at beginning of period	4.6
Cash at end of period	66.8	4.2
Non-Guarantor Subsidiaries
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	0	0
Acquisitions, net of cash acquired		0
Purchases of property, plant and equipment	0	0
Investment in unconsolidated affiliates	-17.9	-19.8
Capital contribution from consolidated affiliate	0	0
Proceeds from sale of assets	0
Net cash used in investing activities	-17.9	-19.8
Proceeds from the issuance of long-term debt	0	0
Principal payments on long-term debt	0	0
Distributions paid	0	0
Contributions from parent	17.9	6.5
Net proceeds from issuance of preferred equity of subsidiary		12.3
Payments on capital leases	0	0
Taxes paid for unit-based compensation vesting	0
Payments of Debt Issuance Costs	0
Net change in payables to affiliate	0	0
Other	0
Net cash provided by financing activities	17.9	18.8
Net change in cash	0	-1
Cash at beginning of period	0
Cash at end of period	0	0
Consolidation, Eliminations
Condensed Financial Statements, Captions [Line Items]
Net cash provided by operating activities	0	0
Acquisitions, net of cash acquired		0
Purchases of property, plant and equipment	0	0
Investment in unconsolidated affiliates	0	0
Capital contribution from consolidated affiliate	17.9	6.5
Proceeds from sale of assets	0
Net cash used in investing activities	17.9	6.5
Proceeds from the issuance of long-term debt	0	0
Principal payments on long-term debt	0	0
Distributions paid	0	0
Contributions from parent	-17.9	-6.5
Net proceeds from issuance of preferred equity of subsidiary		0
Payments on capital leases	0	0
Taxes paid for unit-based compensation vesting	0
Payments of Debt Issuance Costs	0
Net change in payables to affiliate	0	0
Other	0
Net cash provided by financing activities	-17.9	-6.5
Net change in cash	0	0
Cash at beginning of period	0
Cash at end of period	$0	$0