Partners' Capital (Narrative) (Details)																																					1 Months Ended				9 Months Ended	12 Months Ended
	Feb. 12, 2016 USD ($) $ / shares shares	Feb. 05, 2016	Nov. 13, 2015 USD ($) $ / shares	Nov. 06, 2015	Sep. 30, 2015 USD ($) shares	Aug. 14, 2015 USD ($) $ / shares	Aug. 10, 2015 USD ($)	Aug. 07, 2015	May. 15, 2015 USD ($) $ / shares	May. 08, 2015	Feb. 13, 2015 USD ($) $ / shares	Feb. 06, 2015	Jan. 30, 2015 shares	Nov. 14, 2014 USD ($) $ / shares	Nov. 07, 2014	Aug. 14, 2014 USD ($) $ / shares	Aug. 07, 2014	Aug. 07, 2014	Jun. 17, 2014 USD ($) $ / shares	May. 15, 2014 USD ($) $ / shares	May. 08, 2014	Feb. 14, 2014 USD ($) $ / shares	Feb. 07, 2014	Nov. 14, 2013 USD ($) $ / shares	Nov. 08, 2013 USD ($) shares	Nov. 07, 2013	Oct. 07, 2013 USD ($) shares	Aug. 14, 2013 USD ($) $ / shares	Aug. 09, 2013 USD ($) $ / shares	Aug. 07, 2013	Aug. 01, 2013	May. 10, 2013 USD ($) $ / shares	May. 06, 2013 USD ($)	Apr. 30, 2013	Feb. 12, 2013 USD ($) $ / shares	Jan. 31, 2013	Dec. 31, 2014 USD ($) shares	Oct. 31, 2013 USD ($)	Oct. 31, 2013 USD ($)	Jan. 31, 2013 USD ($)	Sep. 30, 2015 USD ($) shares	Dec. 31, 2015 USD ($) $ / shares shares	Dec. 31, 2014 USD ($) $ / shares shares	Dec. 31, 2013 USD ($) shares
Distribution Made to Member or Limited Partner [Line Items]
Distribution to limited partner, distribution date			Nov. 13, 2015			Aug. 14, 2015			May 15, 2015		Feb. 13, 2015			Nov. 14, 2014		Aug. 14, 2014				May 15, 2014		Feb. 14, 2014		Nov. 14, 2013				Aug. 14, 2013
Conversion ratio					2.75																																				2.75
Net proceeds from the issuance of Crestwood Midstream Partners LP Class A preferred units																																										$ (58,800,000)
Maximum Period For Distribution Of Available Cash																																										45 days
Incentive Distribution, Distribution Per Unit | $ / shares																																										$ 0.30
Distribution Made to Limited Partner, Cash Distributions Paid			$ 94,300,000			$ 25,700,000			$ 25,700,000		$ 25,800,000			$ 25,600,000		$ 25,600,000				$ 25,700,000		$ 25,600,000		$ 25,000,000				$ 22,300,000														$ 171,500,000	$ 102,500,000	$ 47,300,000
Per unit rate, in dollars per unit | $ / shares			$ 1.3750			$ 1.3750			$ 1.3750		$ 1.3750			$ 1.3750		$ 1.3750				$ 1.3750		$ 1.3750		$ 1.35				$ 1.30
Distributions to partners																																										(171,500,000)	(102,500,000)	(68,400,000)
Investment in unconsolidated affiliates in period																																										42,000,000	108,600,000	$ 151,500,000
Percentage of voting interests acquired																																												65.00%
Consideration transferred																																								$ 258,000,000
Loss on contingent consideration																																										$ 0	(8,600,000)	$ (31,400,000)
Contribution from issuance of units																																												714,000,000
Distribution made to limited partners | shares																																										1,372,573
Distributions paid to non-controlling partners																																										$ 234,200,000	296,500,000	204,500,000
Dividends, Paid-in-kind																																										12,500,000
Net loss attributable to non-controlling partners																																										$ 636,800,000	66,800,000	57,300,000
Issuance of preferred equity of subsidiary																																											$ 53,900,000	96,100,000
Preferred units, outstanding | shares																																					0					60,718,245	0
Preferred units, issued | shares																																					0					60,718,245	0
Distribution to limited partner, record date				Nov. 06, 2015				Aug. 07, 2015		May 08, 2015		Feb. 06, 2015			Nov. 07, 2014		Aug. 07, 2014				May 08, 2014		Feb. 07, 2014			Nov. 07, 2013				Aug. 07, 2013
Partners' Capital Account, Acquisitions																																												$ 0
Preferred Units, Class C
Distribution Made to Member or Limited Partner [Line Items]
Distribution made to limited partners | shares																																												183,995
Preferred Units, Class D
Distribution Made to Member or Limited Partner [Line Items]
Distribution made to limited partners | shares																																												292,660
Preferred Units, Class A
Distribution Made to Member or Limited Partner [Line Items]
Net proceeds from the issuance of Crestwood Midstream Partners LP Class A preferred units							$ 58,800,000																																				$ 430,500,000
Contribution from issuance of units																																											$ 17,529,879
Partners' Capital Account, Private Placement of Units, Price Per Unit | $ / shares																			$ 25.10																							$ 9.13	$ 25.10
Proceeds from Issuance of Preferred Limited Partners Units, Gross							$ 60,000,000																																				$ 440,000,000
Subsequent Event
Distribution Made to Member or Limited Partner [Line Items]
Distribution made to limited partners | shares	1,404,317
Dividends, Paid-in-kind	$ 12,800,000
Crestwood Equity Partners LP
Distribution Made to Member or Limited Partner [Line Items]
Distribution Made to Limited Partner, Cash Distributions Paid					$ 378,300,000																																				$ 378,300,000
Preferred units, issued | shares					59,345,672																																				59,345,672
Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest																																									99.90%	99.90%
Legacy Crestwood
Distribution Made to Member or Limited Partner [Line Items]
Incentive Distribution, Distribution																																												$ 9,300,000
Crestwood Holdings
Distribution Made to Member or Limited Partner [Line Items]
Cash																																							$ 10,000,000
Cash payments to unitholders upon completion of merger																																	$ 10,000,000
Crestwood Niobrara LLC
Distribution Made to Member or Limited Partner [Line Items]
Net loss attributable to non-controlling partners																																										$ 23,100,000	(16,800,000)	(4,900,000)
Issuance of preferred equity of subsidiary																																											150,000,000
Crestwood Niobrara LLC | Cash distribution
Distribution Made to Member or Limited Partner [Line Items]
Distributions paid to non-controlling partners																																										$ 11,300,000
Crestwood Gas Services GP, LLC [Member]
Distribution Made to Member or Limited Partner [Line Items]
Limited Liability Company (LLC) or Limited Partnership (LP), Members or Limited Partners, Ownership Interest																																									0.10%	0.10%
CMLP
Distribution Made to Member or Limited Partner [Line Items]
Distribution to limited partner, distribution date						Aug. 14, 2015			May 15, 2015		Feb. 13, 2015			Nov. 14, 2014		Aug. 14, 2014				May 15, 2014		Feb. 14, 2014		Nov. 14, 2013				Aug. 14, 2013	Aug. 09, 2013			May 10, 2013			Feb. 12, 2013
Conversion ratio																											1.07
Net proceeds from the issuance of Crestwood Midstream Partners LP Class A preferred units																																										$ 58,800,000	430,500,000
Maximum Period For Distribution Of Available Cash																																										45 days
Distribution Made to General Partner, Cash Distributions Paid																																										$ 31,400,000	41,800,000	26,200,000
Distribution Made to Limited Partner, Cash Distributions Paid						$ 74,300,000			$ 74,300,000		$ 74,300,000			$ 74,100,000		$ 74,100,000				$ 74,200,000		$ 74,100,000		$ 69,500,000				$ 34,300,000	$ 27,400,000			$ 27,400,000			$ 21,000,000							222,900,000	296,500,000	179,600,000
Net Distribution Paid To Limited Partner																																										175,600,000	101,600,000	50,000,000
Per unit rate, in dollars per unit | $ / shares						$ 0.41			$ 0.41		$ 0.41			$ 0.41		$ 0.41				$ 0.41		$ 0.41		$ 0.405				$ 0.400	$ 0.510			$ 0.510			$ 0.510
Cash																																							$ 34,900,000
Distributions to partners																																										(819,500,000)	(470,500,000)	(419,700,000)
Investment in unconsolidated affiliates in period																																										41,800,000	144,400,000	151,500,000
Loss on contingent consideration																																										$ 0	$ (8,600,000)	(31,400,000)
Contribution from issuance of units																																												714,000,000
Distribution made to limited partners | shares																																										1,271,935	387,991
Distributions paid to non-controlling partners																																										$ 0	$ 0	(5,500,000)
Dividends, Paid-in-kind																																										31,900,000	9,700,000
Net loss attributable to non-controlling partners																																										$ (23,100,000)	(16,800,000)	(4,900,000)
Issuance of preferred equity of subsidiary																																											$ 53,900,000	96,100,000
Preferred units, outstanding | shares					21,580,244																																17,917,870				21,580,244	0	17,917,870
Preferred units, issued | shares																																					17,917,870					0	17,917,870
Distribution to limited partner, record date								Aug. 07, 2015		May 08, 2015		Feb. 06, 2015			Nov. 07, 2014			Aug. 07, 2014			May 08, 2014		Feb. 07, 2014			Nov. 07, 2013				Aug. 07, 2013	Aug. 01, 2013			Apr. 30, 2013		Jan. 31, 2013
CMLP
Distribution Made to Member or Limited Partner [Line Items]
Cash																											$ 34,900,000
Distributions to partners																																												(11,800,000)
Arrow Midstream Holdings, LLC
Distribution Made to Member or Limited Partner [Line Items]
Cash																																						$ 550,000,000
Consideration transferred																									$ 750,000,000
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares																									8,826,125
Contribution from issuance of units																																												200,000,000
Arrow Midstream Holdings, LLC | CMLP
Distribution Made to Member or Limited Partner [Line Items]
Contribution from issuance of units																																												200,000,000
Tres Palacios Holdings LLC
Distribution Made to Member or Limited Partner [Line Items]
Investment in unconsolidated affiliates in period																																					$ 132,800,000
Equity method ownership percentage																																										50.01%
Tres Palacios Holdings LLC | Crestwood Niobrara LLC
Distribution Made to Member or Limited Partner [Line Items]
Investment in unconsolidated affiliates in period																																										$ 5,700,000
Tres Palacios Holdings LLC | CMLP
Distribution Made to Member or Limited Partner [Line Items]
Distribution Made to General Partner, Cash Distributions Paid																																											$ 30,600,000
Investment in unconsolidated affiliates in period																																					66,400,000
Equity method ownership percentage																																										50.01%
Jackalope Gas Gathering Services, LLC
Distribution Made to Member or Limited Partner [Line Items]
Equity method ownership percentage																																										50.00%
Jackalope Gas Gathering Services, LLC | Preferred Units
Distribution Made to Member or Limited Partner [Line Items]
Distribution made to limited partners | shares													3,680,570																													11,419,241	2,161,657
Jackalope Gas Gathering Services, LLC | Crestwood Niobrara LLC
Distribution Made to Member or Limited Partner [Line Items]
Investment in unconsolidated affiliates in period																																										$ 25,400,000	$ 105,200,000
Jackalope Gas Gathering Services, LLC | CMLP
Distribution Made to Member or Limited Partner [Line Items]
Investment in unconsolidated affiliates in period																																					$ 107,500,000
Legacy Crestwood Credit Facility
Distribution Made to Member or Limited Partner [Line Items]
Consideration transferred																																								$ 129,000,000
Cash distribution
Distribution Made to Member or Limited Partner [Line Items]
Distributions paid to non-controlling partners																																										$ 222,900,000	296,500,000	179,600,000
Cash distribution | Subsequent Event
Distribution Made to Member or Limited Partner [Line Items]
Distribution to limited partner, distribution date	Feb. 12, 2016
Distribution declared per limited partner unit | $ / shares	$ 1.375
Distribution to limited partner, record date		Feb. 05, 2016
Preferred Partner
Distribution Made to Member or Limited Partner [Line Items]
Partners' Capital, Distribution Amount Per Share | $ / shares																																										$ 0.2567
Partners' Capital, Contingent Distribution Amount Per Share | $ / shares																																										$ 0.2111
Partner's Capital, Unpaid Distribution, Accrual Percentage																																										2.8125%
Preferred Partner | CMLP
Distribution Made to Member or Limited Partner [Line Items]
Partners' Capital, Distribution Amount Per Share | $ / shares																																										$ 0.5804
Partners' Capital Account, Private Placement of Units, Price Per Unit | $ / shares																																										$ 25.10
Limited Partners | CMLP
Distribution Made to Member or Limited Partner [Line Items]
Net loss attributable to non-controlling partners																																										$ 683,000,000	(100,800,000)	$ (62,200,000)
Subordinated Unit | Limited Partners
Distribution Made to Member or Limited Partner [Line Items]
Distribution made to limited partners | shares																																												438,789
Partners' Capital Account, Units, Cash Distribution Threshold, Quarterly Distribution | $ / shares																																										$ 1.30
Partners' Capital Account, Units, Conversion Threshold, Cumulative Distribution | $ / shares																																										$ 5.20
Crestwood Holdings | Crestwood Equity Partners LP
Distribution Made to Member or Limited Partner [Line Items]
Shares issued by acquiree | shares																											14,300,000
Crestwood Holdings | Majority Shareholder
Distribution Made to Member or Limited Partner [Line Items]
Shares exchanged by acquirer | shares																											7,100,000
Non-Controlling Partners
Distribution Made to Member or Limited Partner [Line Items]
Net proceeds from the issuance of Crestwood Midstream Partners LP Class A preferred units																																										$ (58,800,000)
Contribution from issuance of units																																												$ 714,000,000
Issuance of preferred equity of subsidiary																																											53,900,000	96,100,000
Partners' Capital Account, Acquisitions																																												(182,300,000)
Non-Controlling Partners | CMLP
Distribution Made to Member or Limited Partner [Line Items]
Net proceeds from the issuance of Crestwood Midstream Partners LP Class A preferred units																																										0	0
Contribution from issuance of units																																												0
Issuance of preferred equity of subsidiary																																											53,900,000	96,100,000
Non-Controlling Partners | Arrow Midstream Holdings, LLC
Distribution Made to Member or Limited Partner [Line Items]
Contribution from issuance of units																																												200,000,000
Non-Controlling Partners | Arrow Midstream Holdings, LLC | CMLP
Distribution Made to Member or Limited Partner [Line Items]
Contribution from issuance of units																																												0
Limited Partners
Distribution Made to Member or Limited Partner [Line Items]
Net proceeds from the issuance of Crestwood Midstream Partners LP Class A preferred units																																										0
Contribution from issuance of units																																												0
Issuance of preferred equity of subsidiary																																											0	0
Partners' Capital Account, Acquisitions																																												182,300,000
Limited Partners | CMLP
Distribution Made to Member or Limited Partner [Line Items]
Net proceeds from the issuance of Crestwood Midstream Partners LP Class A preferred units																																										$ 0	0
Contribution from issuance of units																																												714,000,000
Issuance of preferred equity of subsidiary																																											$ 0	0
Limited Partners | Arrow Midstream Holdings, LLC
Distribution Made to Member or Limited Partner [Line Items]
Contribution from issuance of units																																												0
Limited Partners | Arrow Midstream Holdings, LLC | CMLP
Distribution Made to Member or Limited Partner [Line Items]
Contribution from issuance of units																																												$ 200,000,000
Maximum | Class A Purchasers [Member] | Preferred Units, Class A
Distribution Made to Member or Limited Partner [Line Items]
Contribution from issuance of units																			$ 500,000,000