Segments (Summary Of Segment Information) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2022 USD ($) segment	Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($)
Net income (loss)	$ 22.2	$ (38.3)
Number of Operating Segments | segment	3
Depreciation, amortization and accretion	$ 74.8	59.2
Segment Reporting Information, Additional Information [Abstract]
Revenues	1,583.8	1,032.7
Costs of product/services sold	1,364.4	813.8
Operations and maintenance	42.4	32.8
General and administrative	43.4	18.7
Gain (loss) on long-lived assets	(3.8)	(1.4)
Earnings (loss) from unconsolidated affiliates, net	3.0	(103.7)
Other income, net	0.3	0.0
EBITDA	133.1	62.3
Assets	6,240.1		$ 4,445.7
Intersegment Eliminations
Segment Reporting Information, Additional Information [Abstract]
Revenues	(127.4)	(105.3)
Gathering and Processing North | Operating Segments
Segment Reporting Information, Additional Information [Abstract]
Revenues	362.6	235.1
Gathering and Processing South | Operating Segments
Segment Reporting Information, Additional Information [Abstract]
Revenues	30.7	24.6
Storage and Logistics | Operating Segments
Segment Reporting Information, Additional Information [Abstract]
Revenues	1,317.9	878.3
Crestwood Midstream Partners LP
Net income (loss)	20.2	(40.4)
Depreciation, amortization and accretion	78.2	62.8
Segment Reporting Information, Additional Information [Abstract]
Revenues	1,583.8	1,032.7
Costs of product/services sold	1,364.4	813.8
Operations and maintenance	42.4	32.8
General and administrative	41.7	17.2
Gain (loss) on long-lived assets	(3.8)	(1.4)
Earnings (loss) from unconsolidated affiliates, net	3.0	(103.7)
EBITDA	134.5	63.8
Assets	6,362.1		4,571.2
Crestwood Midstream Partners LP | Corporate, Non-Segment
Segment Reporting Information, Additional Information [Abstract]
Revenues	0.0	0.0
Costs of product/services sold	0.0	0.0
Operations and maintenance	0.0	0.0
General and administrative	41.7	17.2
Gain (loss) on long-lived assets	0.0	0.0
Earnings (loss) from unconsolidated affiliates, net	0.0	0.0
EBITDA	(41.7)	(17.2)
Assets	24.3		20.7
Crestwood Midstream Partners LP | Corporate and Eliminations [Member]
Segment Reporting Information, Additional Information [Abstract]
Revenues	0.0	0.0
Crestwood Midstream Partners LP | Gathering and Processing North | Operating Segments
Segment Reporting Information, Additional Information [Abstract]
Revenues	235.2	129.8
Costs of product/services sold	205.6	116.2
Operations and maintenance	23.7	15.1
General and administrative	0.0	0.0
Gain (loss) on long-lived assets	0.0	(0.2)
Earnings (loss) from unconsolidated affiliates, net	0.0	0.0
EBITDA	133.3	103.6
Assets	4,090.1		2,408.0
Crestwood Midstream Partners LP | Gathering and Processing North | Intersegment Eliminations
Segment Reporting Information, Additional Information [Abstract]
Revenues	127.4	105.3
Crestwood Midstream Partners LP | Gathering and Processing South | Operating Segments
Segment Reporting Information, Additional Information [Abstract]
Revenues	30.7	24.6
Costs of product/services sold	(0.6)	0.3
Operations and maintenance	6.7	6.3
General and administrative	0.0	0.0
Gain (loss) on long-lived assets	0.2	(1.3)
Earnings (loss) from unconsolidated affiliates, net	2.6	(0.8)
EBITDA	27.4	15.9
Assets	1,150.4		1,017.4
Crestwood Midstream Partners LP | Gathering and Processing South | Intersegment Eliminations
Segment Reporting Information, Additional Information [Abstract]
Revenues	0.0	0.0
Crestwood Midstream Partners LP | Storage and Logistics | Operating Segments
Segment Reporting Information, Additional Information [Abstract]
Revenues	1,317.9	878.3
Costs of product/services sold	1,159.4	697.3
Operations and maintenance	12.0	11.4
General and administrative	0.0	0.0
Gain (loss) on long-lived assets	(4.0)	0.1
Earnings (loss) from unconsolidated affiliates, net	0.4	(102.9)
EBITDA	15.5	(38.5)
Assets	1,097.3		1,125.1
Crestwood Midstream Partners LP | Storage and Logistics | Intersegment Eliminations
Segment Reporting Information, Additional Information [Abstract]
Revenues	(127.4)	(105.3)
Crestwood Equity Partners LP
Segment Reporting Information, Additional Information [Abstract]
General and administrative	1.7	1.5
Other income, net	0.3
EBITDA	133.1	62.3
Assets	6,240.1		4,445.7
Crestwood Equity Partners LP | Corporate, Non-Segment
Segment Reporting Information, Additional Information [Abstract]
General and administrative	1.7	1.5
Other income, net	0.3
EBITDA	(43.1)	(18.7)
Assets	29.6		26.1
Crestwood Equity Partners LP | Gathering and Processing North | Operating Segments
Segment Reporting Information, Additional Information [Abstract]
General and administrative	0.0	0.0
Other income, net	0.0
EBITDA	133.3	103.6
Assets	4,090.1		2,408.0
Crestwood Equity Partners LP | Gathering and Processing South | Operating Segments
Segment Reporting Information, Additional Information [Abstract]
General and administrative	0.0	0.0
Other income, net	0.0
EBITDA	27.4	15.9
Assets	1,023.1		886.5
Crestwood Equity Partners LP | Storage and Logistics | Operating Segments
Segment Reporting Information, Additional Information [Abstract]
General and administrative	0.0	0.0
Other income, net	0.0
EBITDA	15.5	$ (38.5)
Assets	$ 1,097.3		$ 1,125.1