Segments (Summary Of Segment Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Jan. 01, 2020
Segment Reporting Information [Line Items]
Operating revenues	$ 4,569.0	$ 2,254.3	$ 3,181.9
Costs of product/services sold	3,843.9	1,600.5	2,544.9
Operations and maintenance	121.0	131.8	138.8
General and administrative	97.6	91.5	103.4
Gain (loss) on long-lived assets, net	(39.6)	(26.0)	(6.2)
Goodwill impairment	0.0	(80.3)	0.0
Gain on acquisition	0.0	0.0	209.4
Earnings (loss) from unconsolidated affiliates, net	(120.4)	32.5	32.8
Other income (expense), net	0.1	(0.7)	0.6
EBITDA	346.6	356.0	631.4
Goodwill	138.6	138.6		$ 218.9
Assets	4,445.7	5,243.7
Payments to Acquire Property, Plant, and Equipment	83.2	168.3	455.5
CMLP
Segment Reporting Information [Line Items]
Operating revenues	4,569.0	2,254.3	3,181.9
Costs of product/services sold	3,843.9	1,600.5	2,544.9
Operations and maintenance	121.0	131.8	138.8
General and administrative	90.2	86.7	98.2
Gain (loss) on long-lived assets, net	(39.4)	(26.0)	(6.2)
Goodwill impairment	0.0	(80.3)	0.0
Gain on acquisition	0.0	0.0	209.4
Earnings (loss) from unconsolidated affiliates, net	(120.4)	32.5	32.8
Other income (expense), net	0.0	0.0	0.2
EBITDA	354.1	361.5	636.2
Goodwill	138.6	138.6
Assets	4,571.2	5,385.5
Payments to Acquire Property, Plant, and Equipment	81.3	168.3	455.5
Crestwood Equity Partners LP
Segment Reporting Information [Line Items]
General and administrative	7.4	4.8	5.2
Gain (loss) on long-lived assets, net	(0.2)
Other income (expense), net	0.1	(0.7)	0.4
EBITDA	346.6	356.0	631.4
Assets	4,445.7	5,243.7
Payments to Acquire Property, Plant, and Equipment	83.2	168.3	455.5
Corporate, Non-Segment | CMLP
Segment Reporting Information [Line Items]
Operating revenues	0.0	0.0	0.0
Costs of product/services sold	0.0	0.0	0.0
Operations and maintenance	0.0	0.0	0.0
General and administrative	90.2	86.7	98.2
Gain (loss) on long-lived assets, net	0.1	0.2	0.2
Goodwill impairment		0.0
Gain on acquisition			0.0
Earnings (loss) from unconsolidated affiliates, net	0.0	0.0	0.0
Other income (expense), net			0.2
EBITDA	(90.1)	(86.5)	(97.8)
Assets	20.7	26.2
Payments to Acquire Property, Plant, and Equipment	0.7	1.1	1.9
Corporate, Non-Segment | Crestwood Equity Partners LP
Segment Reporting Information [Line Items]
General and administrative	7.4	4.8	5.2
Gain (loss) on long-lived assets, net	(0.2)
Other income (expense), net	0.1	(0.7)	0.4
EBITDA	(97.6)	(92.0)	(102.6)
Assets	26.1	29.5
Payments to Acquire Property, Plant, and Equipment	1.9	0.0	0.0
Intersegment Eliminations
Segment Reporting Information [Line Items]
Operating revenues	(459.3)	(159.8)	(175.0)
Corporate and Eliminations | CMLP
Segment Reporting Information [Line Items]
Operating revenues	0.0	0.0	0.0
Storage and Logistics | Operating Segments
Segment Reporting Information [Line Items]
Operating revenues	3,888.4	1,622.9	2,346.1
Storage and Logistics | Operating Segments | CMLP
Segment Reporting Information [Line Items]
Operating revenues	3,888.4	1,622.9	2,346.1
Costs of product/services sold	3,289.8	1,339.0	2,018.8
Operations and maintenance	47.0	46.9	40.1
General and administrative	0.0	0.0	0.0
Gain (loss) on long-lived assets, net	0.7	(2.4)	(0.2)
Goodwill impairment		0.0
Gain on acquisition			0.0
Earnings (loss) from unconsolidated affiliates, net	(130.0)	33.5	34.9
Other income (expense), net			0.0
EBITDA	(37.0)	108.3	146.9
Assets	1,125.1	1,749.6
Payments to Acquire Property, Plant, and Equipment	6.6	7.5	5.9
Storage and Logistics | Operating Segments | Crestwood Equity Partners LP
Segment Reporting Information [Line Items]
General and administrative	0.0	0.0	0.0
Gain (loss) on long-lived assets, net	0.0
Other income (expense), net	0.0	0.0	0.0
EBITDA	(37.0)	108.3	146.9
Assets	1,125.1	1,749.6
Storage and Logistics | Intersegment Eliminations | CMLP
Segment Reporting Information [Line Items]
Operating revenues	(459.3)	(159.8)	(175.0)
Gathering and Processing South Segment | Operating Segments
Segment Reporting Information [Line Items]
Operating revenues	105.9	120.3	149.0
Gathering and Processing South Segment | Operating Segments | CMLP
Segment Reporting Information [Line Items]
Operating revenues	105.9	121.0	148.9
Costs of product/services sold	0.9	0.5	2.1
Operations and maintenance	22.9	29.2	37.9
General and administrative	0.0	0.0	0.0
Gain (loss) on long-lived assets, net	(40.6)	(20.0)	(2.0)
Goodwill impairment		0.0
Gain on acquisition			0.0
Earnings (loss) from unconsolidated affiliates, net	9.6	(1.0)	(5.8)
Other income (expense), net			0.0
EBITDA	51.1	69.6	101.2
Assets	1,017.4	1,129.3
Payments to Acquire Property, Plant, and Equipment	7.9	3.2	13.3
Gathering and Processing South Segment | Operating Segments | Crestwood Equity Partners LP
Segment Reporting Information [Line Items]
General and administrative	0.0	0.0	0.0
Gain (loss) on long-lived assets, net	0.0
Other income (expense), net	0.0	0.0	0.0
EBITDA	51.1	69.6	101.2
Assets	886.5	984.2
Gathering and Processing South Segment | Intersegment Eliminations | CMLP
Segment Reporting Information [Line Items]
Operating revenues	0.0	(0.7)	0.1
Gathering and Processing North Segment | Operating Segments
Segment Reporting Information [Line Items]
Operating revenues	1,034.0	670.9	861.8
Gathering and Processing North Segment | Operating Segments | CMLP
Segment Reporting Information [Line Items]
Operating revenues	574.7	510.4	686.9
Costs of product/services sold	553.2	261.0	524.0
Operations and maintenance	51.1	55.7	60.8
General and administrative	0.0	0.0	0.0
Gain (loss) on long-lived assets, net	0.4	(3.8)	(4.2)
Goodwill impairment		(80.3)
Gain on acquisition			(209.4)
Earnings (loss) from unconsolidated affiliates, net	0.0	0.0	3.7
Other income (expense), net			0.0
EBITDA	430.1	270.1	485.9
Assets	2,408.0	2,480.4
Payments to Acquire Property, Plant, and Equipment	66.1	156.5	434.4
Gathering and Processing North Segment | Operating Segments | Crestwood Equity Partners LP
Segment Reporting Information [Line Items]
General and administrative	0.0	0.0	0.0
Gain (loss) on long-lived assets, net	0.0
Other income (expense), net	0.0	0.0	0.0
EBITDA	430.1	270.1	485.9
Assets	2,408.0	2,480.4
Gathering and Processing North Segment | Intersegment Eliminations | CMLP
Segment Reporting Information [Line Items]
Operating revenues	$ 459.3	$ 160.5	$ 174.9