Condensed Consolidating Financial Information (Statements Of Operations) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Revenues	$ 519.2	$ 823.6	$ 1,599.8	$ 2,342.2
Costs of product/services sold	358.7	657.4	1,118.8	1,890.2
Operating expenses and other:
Operations and maintenance	31.0	36.0	100.2	99.3
General and administrative	19.6	24.9	64.0	84.4
Depreciation, amortization and accretion	60.8	51.5	177.9	140.6
Loss on long-lived assets, net	21.3	0.1	26.1	2.1
Gain on acquisition	0.0	0.0	0.0	(209.4)
Goodwill impairment	0.0	0.0	80.3	0.0
Total expenses	132.7	112.5	448.5	117.0
Operating income (loss)	27.8	53.7	32.5	335.0
Earnings from unconsolidated affiliates, net	10.5	10.4	24.4	21.0
Interest and debt expense, net	(33.7)	(30.6)	(100.3)	(83.3)
Income (loss) before income taxes	4.6	33.6	(43.2)	273.0
(Provision) benefit for income taxes	0.0	0.0	0.1	(0.3)
Net income (loss)	4.6	33.6	(43.1)	272.7
Net income attributable to non-controlling partner in subsidiary	10.3	9.9	30.4	24.5
Net income (loss) attributable to parent	(5.7)	23.7	(73.5)	248.2
Eliminations
Revenues	0.0	(0.7)	0.0	(0.7)
Costs of product/services sold	0.0	(0.7)	0.0	(0.7)
Operating expenses and other:
Operations and maintenance	0.0	0.0	0.0	0.0
General and administrative	0.0	0.0	0.0	0.0
Depreciation, amortization and accretion	0.0	0.0	0.0	0.0
Loss on long-lived assets, net	0.0	0.0	0.0	0.0
Gain on acquisition				0.0
Goodwill impairment			0.0
Total expenses	0.0	0.0	0.0	0.0
Operating income (loss)	0.0	0.0	0.0	0.0
Earnings from unconsolidated affiliates, net	0.0	0.0	0.0	0.0
Interest and debt expense, net	0.0	0.0	0.0	0.0
Loss from unconsolidated affiliates	(36.0)	(62.7)	(62.5)	(363.7)
Income (loss) before income taxes		(62.7)	(62.5)	(363.7)
(Provision) benefit for income taxes		0.0	0.0	0.0
Net income (loss)	(36.0)	(62.7)	(62.5)	(363.7)
Net income attributable to non-controlling partner in subsidiary	0.0	0.0	0.0	0.0
Net income (loss) attributable to parent	(36.0)	(62.7)	(62.5)	(363.7)
Non-Guarantor Subsidiaries | Reportable Legal Entities
Revenues	12.6	23.2	56.3	43.4
Costs of product/services sold	0.0	0.7	0.2	0.7
Operating expenses and other:
Operations and maintenance	4.9	5.2	15.8	12.4
General and administrative	0.0	0.0	0.0	0.0
Depreciation, amortization and accretion	14.5	9.6	40.6	19.3
Loss on long-lived assets, net	(0.9)	0.0	0.9	0.0
Gain on acquisition				(209.4)
Goodwill impairment			80.3
Total expenses	18.5	14.8	137.6	(177.7)
Operating income (loss)	(5.9)	7.7	(81.5)	220.4
Earnings from unconsolidated affiliates, net	10.5	10.4	24.4	21.0
Interest and debt expense, net	0.0	0.1	0.0	0.1
Loss from unconsolidated affiliates	0.0	0.0	0.0	0.0
Income (loss) before income taxes		18.2	(57.1)	241.5
(Provision) benefit for income taxes		0.0	0.0	0.0
Net income (loss)	4.6	18.2	(57.1)	241.5
Net income attributable to non-controlling partner in subsidiary	10.3	9.9	30.4	24.5
Net income (loss) attributable to parent	(5.7)	8.3	(87.5)	217.0
Crestwood Midstream Partners LP
Revenues	519.2	823.6	1,599.8	2,342.2
Costs of product/services sold	358.7	657.4	1,118.8	1,890.2
Operating expenses and other:
Operations and maintenance	31.0	36.0	100.2	99.3
General and administrative	18.5	23.7	60.4	80.6
Depreciation, amortization and accretion	64.2	55.1	188.4	151.2
Loss on long-lived assets, net	21.3	0.1	26.1	2.1
Gain on acquisition				(209.4)
Goodwill impairment			80.3
Total expenses	135.0	114.9	455.4	123.8
Operating income (loss)	25.5	51.3	25.6	328.2
Earnings from unconsolidated affiliates, net	10.5	10.4	24.4	21.0
Interest and debt expense, net	(33.7)	(30.6)	(100.3)	(83.3)
Loss from unconsolidated affiliates	0.0	0.0	0.0	0.0
Income (loss) before income taxes		31.1	(50.3)	265.9
(Provision) benefit for income taxes		0.1	0.2	(0.2)
Net income (loss)	2.3	31.2	(50.1)	265.7
Net income attributable to non-controlling partner in subsidiary	10.3	9.9	30.4	24.5
Net income (loss) attributable to parent	(8.0)	21.3	(80.5)	241.2
Guarantor Subsidiaries | Reportable Legal Entities
Revenues	506.6	801.1	1,543.5	2,299.5
Costs of product/services sold	358.7	657.4	1,118.6	1,890.2
Operating expenses and other:
Operations and maintenance	26.1	30.8	84.4	86.9
General and administrative	8.1	13.0	17.3	41.5
Depreciation, amortization and accretion	49.7	45.5	147.8	131.9
Loss on long-lived assets, net	22.2	0.1	25.2	2.1
Gain on acquisition				0.0
Goodwill impairment			0.0
Total expenses	106.1	89.4	274.7	262.4
Operating income (loss)	41.8	54.3	150.2	146.9
Earnings from unconsolidated affiliates, net	0.0	0.0	0.0	0.0
Interest and debt expense, net	(0.1)	0.0	(0.4)	0.0
Loss from unconsolidated affiliates	0.0	0.0	0.0	0.0
Income (loss) before income taxes		54.3	149.8	146.9
(Provision) benefit for income taxes		0.1	0.2	(0.2)
Net income (loss)	41.7	54.4	150.0	146.7
Net income attributable to non-controlling partner in subsidiary	0.0	0.0	0.0	0.0
Net income (loss) attributable to parent	41.7	54.4	150.0	146.7
Parent Company, Crestwood Midstream Partners, LP | Reportable Legal Entities
Revenues	0.0	0.0	0.0	0.0
Costs of product/services sold	0.0	0.0	0.0	0.0
Operating expenses and other:
Operations and maintenance	0.0	0.0	0.0	0.0
General and administrative	10.4	10.7	43.1	39.1
Depreciation, amortization and accretion	0.0	0.0	0.0	0.0
Loss on long-lived assets, net	0.0	0.0	0.0	0.0
Gain on acquisition				0.0
Goodwill impairment			0.0
Total expenses	10.4	10.7	43.1	39.1
Operating income (loss)	(10.4)	(10.7)	(43.1)	(39.1)
Earnings from unconsolidated affiliates, net	0.0	0.0	0.0	0.0
Interest and debt expense, net	(33.6)	(30.7)	(99.9)	(83.4)
Loss from unconsolidated affiliates	36.0	62.7	62.5	363.7
Income (loss) before income taxes		21.3	(80.5)	241.2
(Provision) benefit for income taxes		0.0	0.0	0.0
Net income (loss)	(8.0)	21.3	(80.5)	241.2
Net income attributable to non-controlling partner in subsidiary	0.0	0.0	0.0	0.0
Net income (loss) attributable to parent	$ (8.0)	$ 21.3	$ (80.5)	$ 241.2