Segments (Summary Of Segment Information) (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022 USD ($)	Jun. 30, 2021 USD ($)	Jun. 30, 2022 USD ($) segment	Jun. 30, 2021 USD ($)	Dec. 31, 2021 USD ($)
Net income (loss)	$ 39.4	$ (38.1)	$ 61.6	$ (76.4)
Number of Operating Segments | segment			3
Depreciation, amortization and accretion	80.6	58.8	$ 155.4	118.0
Segment Reporting Information, Additional Information [Abstract]
Revenues	1,448.0	929.6	3,031.8	1,962.3
Costs of product/services sold	1,213.2	797.2	2,577.6	1,611.0
Operations and maintenance	46.6	25.8	89.0	58.6
General and administrative	26.5	22.8	69.9	41.5
Gain (loss) on long-lived assets	(7.2)	0.3	(11.0)	(1.1)
Earnings (loss) from unconsolidated affiliates, net	6.0	(27.1)	9.0	(130.8)
Other income (expense), net	(0.1)	0.1	0.2	0.1
EBITDA	160.4	57.1	293.5	119.4
Assets	6,202.8		6,202.8		$ 4,445.7
Intersegment Eliminations
Segment Reporting Information, Additional Information [Abstract]
Revenues	(151.6)	(84.2)	(279.0)	(189.5)
Gathering and Processing North | Operating Segments
Segment Reporting Information, Additional Information [Abstract]
Revenues	431.0	232.8	793.6	467.9
Gathering and Processing South | Operating Segments
Segment Reporting Information, Additional Information [Abstract]
Revenues	35.3	24.7	66.0	49.3
Storage and Logistics | Operating Segments
Segment Reporting Information, Additional Information [Abstract]
Revenues	1,133.3	756.3	2,451.2	1,634.6
Crestwood Midstream Partners LP
Net income (loss)	(14.6)	(38.5)	5.6	(78.9)
Depreciation, amortization and accretion	83.0	62.2	161.2	125.0
Segment Reporting Information, Additional Information [Abstract]
Revenues	1,448.0	929.6	3,031.8	1,962.3
Costs of product/services sold	1,213.2	797.2	2,577.6	1,611.0
Operations and maintenance	46.6	25.8	89.0	58.6
General and administrative	25.0	19.7	66.7	36.9
Gain (loss) on long-lived assets	(60.5)	0.3	(64.3)	(1.1)
Earnings (loss) from unconsolidated affiliates, net	6.0	(27.1)	9.0	(130.8)
EBITDA	108.7	60.1	243.2	123.9
Assets	6,268.7		6,268.7		4,571.2
Crestwood Midstream Partners LP | Corporate, Non-Segment
Segment Reporting Information, Additional Information [Abstract]
Revenues	0.0	0.0	0.0	0.0
Costs of product/services sold	0.0	0.0	0.0	0.0
Operations and maintenance	0.0	0.0	0.0	0.0
General and administrative	25.0	19.7	66.7	36.9
Gain (loss) on long-lived assets	0.0	0.0	0.0	0.0
Earnings (loss) from unconsolidated affiliates, net	0.0	0.0	0.0	0.0
EBITDA	(25.0)	(19.7)	(66.7)	(36.9)
Assets	16.4		16.4		20.7
Crestwood Midstream Partners LP | Corporate and Eliminations [Member]
Segment Reporting Information, Additional Information [Abstract]
Revenues	0.0	0.0	0.0	0.0
Crestwood Midstream Partners LP | Gathering and Processing North | Operating Segments
Segment Reporting Information, Additional Information [Abstract]
Revenues	279.4	148.6	514.6	278.4
Costs of product/services sold	250.8	120.5	456.4	236.7
Operations and maintenance	27.5	9.0	51.2	24.1
General and administrative	0.0	0.0	0.0	0.0
Gain (loss) on long-lived assets	0.0	0.3	0.0	0.1
Earnings (loss) from unconsolidated affiliates, net	0.0	0.0	0.0	0.0
EBITDA	152.7	103.6	286.0	207.2
Assets	4,082.7		4,082.7		2,408.0
Crestwood Midstream Partners LP | Gathering and Processing North | Intersegment Eliminations
Segment Reporting Information, Additional Information [Abstract]
Revenues	151.6	84.2	279.0	189.5
Crestwood Midstream Partners LP | Gathering and Processing South | Operating Segments
Segment Reporting Information, Additional Information [Abstract]
Revenues	35.3	24.7	66.0	49.3
Costs of product/services sold	0.6	0.1	0.0	0.4
Operations and maintenance	7.6	5.7	14.3	12.0
General and administrative	0.0	0.0	0.0	0.0
Gain (loss) on long-lived assets	(60.4)	0.0	(60.2)	(1.3)
Earnings (loss) from unconsolidated affiliates, net	4.8	1.0	7.4	0.2
EBITDA	(28.5)	19.9	(1.1)	35.8
Assets	1,077.9		1,077.9		1,017.4
Crestwood Midstream Partners LP | Gathering and Processing South | Intersegment Eliminations
Segment Reporting Information, Additional Information [Abstract]
Revenues	0.0	0.0	0.0	0.0
Crestwood Midstream Partners LP | Storage and Logistics | Operating Segments
Segment Reporting Information, Additional Information [Abstract]
Revenues	1,133.3	756.3	2,451.2	1,634.6
Costs of product/services sold	961.8	676.6	2,121.2	1,373.9
Operations and maintenance	11.5	11.1	23.5	22.5
General and administrative	0.0	0.0	0.0	0.0
Gain (loss) on long-lived assets	(0.1)	0.0	(4.1)	0.1
Earnings (loss) from unconsolidated affiliates, net	1.2	(28.1)	1.6	(131.0)
EBITDA	9.5	(43.7)	25.0	(82.2)
Assets	1,091.7		1,091.7		1,125.1
Crestwood Midstream Partners LP | Storage and Logistics | Intersegment Eliminations
Segment Reporting Information, Additional Information [Abstract]
Revenues	(151.6)	(84.2)	(279.0)	(189.5)
Crestwood Equity Partners LP
Segment Reporting Information, Additional Information [Abstract]
General and administrative	1.5	3.1	3.2	4.6
Elimination of Loss on Long-Lived Assets	53.3		53.3
Other income (expense), net	(0.1)	0.1	0.2	0.1
EBITDA	160.4	57.1	293.5	119.4
Assets	6,202.8		6,202.8		4,445.7
Crestwood Equity Partners LP | Corporate, Non-Segment
Segment Reporting Information, Additional Information [Abstract]
General and administrative	1.5	3.1	3.2	4.6
Elimination of Loss on Long-Lived Assets	0.0		0.0
Other income (expense), net	(0.1)	0.1	0.2	0.1
EBITDA	(26.6)	(22.7)	(69.7)	(41.4)
Assets	22.2		22.2		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	0.0	0.0
Elimination of Loss on Long-Lived Assets	0.0		0.0
Other income (expense), net	0.0	0.0	0.0	0.0
EBITDA	152.7	103.6	286.0	207.2
Assets	4,082.7		4,082.7		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	0.0	0.0
Elimination of Loss on Long-Lived Assets	53.3		53.3
Other income (expense), net	0.0	0.0	0.0	0.0
EBITDA	24.8	19.9	52.2	35.8
Assets	1,006.2		1,006.2		886.5
Crestwood Equity Partners LP | Storage and Logistics | Operating Segments
Segment Reporting Information, Additional Information [Abstract]
General and administrative	0.0	0.0	0.0	0.0
Elimination of Loss on Long-Lived Assets	0.0		0.0
Other income (expense), net	0.0	0.0	0.0	0.0
EBITDA	9.5	$ (43.7)	25.0	$ (82.2)
Assets	$ 1,091.7		$ 1,091.7		$ 1,125.1