Condensed Consolidating Financial Information (Statements Of Operations) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues:
Revenues	$ 3,181.9	$ 3,654.1	$ 3,880.9
Costs of product/services sold (exclusive of items shown separately below):
Product costs - related party (Note 16)	45.4	134.7	15.3
Total costs of products/services sold	2,544.9	3,129.4	3,374.7
Operating expenses and other:
Operations and maintenance	138.8	125.8	136.0
General and administrative	103.4	88.1	96.5
Depreciation, amortization and accretion	195.8	168.7	191.7
Goodwill impairment	0.0	0.0	38.8
Loss on contingent consideration	0.0	0.0	57.0
Loss on long-lived assets, net	6.2	28.6	65.6
Gain on acquisition	(209.4)	0.0	0.0
Total expenses	234.8	411.2	585.6
Operating income (loss)	402.2	113.5	(79.4)
Other income (expense):
Earnings from unconsolidated affiliates, net	32.8	53.3	47.8
Interest and debt expense, net	(115.4)	(99.2)	(99.4)
Loss on modification/extinguishment of debt	0.0	(0.9)	(37.7)
Other income, net	0.6	0.4	1.3
Income (loss) before income taxes	320.2	67.1	(167.4)
(Provision) benefit for income taxes	(0.3)	(0.1)	0.8
Net income (loss)	319.9	67.0	(166.6)
Net income attributable to non-controlling partner	34.8	16.2	25.3
Net income (loss) attributable to parent	285.1	50.8	(191.9)
Net income attributable to preferred units	60.1	60.1	62.5
Net income (loss) attributable to partners	225.0	(9.3)	(254.4)
Eliminations
Revenues:
Revenues	0.0	0.0	0.0
Costs of product/services sold (exclusive of items shown separately below):
Total costs of products/services sold	0.0	0.0	0.0
Operating expenses and other:
Operations and maintenance	0.0	0.0	0.0
General and administrative	0.0	0.0	0.0
Depreciation, amortization and accretion	0.0	0.0	0.0
Goodwill impairment			0.0
Loss on contingent consideration			0.0
Loss on long-lived assets, net	0.0	0.0	0.0
Gain on acquisition	0.0
Total expenses	0.0	0.0	0.0
Operating income (loss)	0.0	0.0	0.0
Other income (expense):
Earnings from unconsolidated affiliates, net	0.0	0.0	0.0
Interest and debt expense, net	0.0	0.0	0.0
Loss on modification/extinguishment of debt		0.0	0.0
Other income, net			0.0
Other income, net	0.0
Loss from unconsolidated affiliates	(442.5)	(197.6)	(3.9)
Income (loss) before income taxes	(442.5)
(Provision) benefit for income taxes	0.0
Net income (loss)	(442.5)	(197.6)	(3.9)
Net income attributable to non-controlling partner	0.0	0.0	0.0
Net income (loss) attributable to parent	(442.5)	(197.6)
Net income (loss) attributable to partners			(3.9)
Parent Company, Crestwood Midstream Partners, LP | Reportable Legal Entities
Revenues:
Revenues	0.0	0.0	0.0
Costs of product/services sold (exclusive of items shown separately below):
Total costs of products/services sold	0.0	0.0	0.0
Operating expenses and other:
Operations and maintenance	0.0	0.0	0.0
General and administrative	51.2	55.1	67.6
Depreciation, amortization and accretion	0.0	0.0	0.0
Goodwill impairment			0.0
Loss on contingent consideration			0.0
Loss on long-lived assets, net	0.0	0.0	0.0
Gain on acquisition	0.0
Total expenses	51.2	55.1	67.6
Operating income (loss)	(51.2)	(55.1)	(67.6)
Other income (expense):
Earnings from unconsolidated affiliates, net	0.0	0.0	0.0
Interest and debt expense, net	(115.5)	(99.2)	(99.4)
Loss on modification/extinguishment of debt		(0.9)	(37.7)
Other income, net			0.0
Other income, net	0.0
Loss from unconsolidated affiliates	442.5	197.6	3.9
Income (loss) before income taxes	275.8
(Provision) benefit for income taxes	0.0
Net income (loss)	275.8	42.4	(200.8)
Net income attributable to non-controlling partner	0.0	0.0	0.0
Net income (loss) attributable to parent	275.8	42.4
Net income (loss) attributable to partners			(200.8)
Guarantor Subsidiaries | Reportable Legal Entities
Revenues:
Revenues	3,111.8	3,654.1	3,880.9
Costs of product/services sold (exclusive of items shown separately below):
Total costs of products/services sold	2,544.9	3,129.4	3,374.7
Operating expenses and other:
Operations and maintenance	120.0	125.8	136.0
General and administrative	47.0	28.4	25.5
Depreciation, amortization and accretion	179.4	181.4	202.7
Goodwill impairment			38.8
Loss on contingent consideration			0.0
Loss on long-lived assets, net	6.2	28.6	65.6
Gain on acquisition	0.0
Total expenses	352.6	364.2	468.6
Operating income (loss)	214.3	160.5	37.6
Other income (expense):
Earnings from unconsolidated affiliates, net	0.0	0.0	0.0
Interest and debt expense, net	0.0	0.0	0.0
Loss on modification/extinguishment of debt		0.0	0.0
Other income, net			0.8
Other income, net	0.2
Loss from unconsolidated affiliates	0.0	0.0	0.0
Income (loss) before income taxes	214.5
(Provision) benefit for income taxes	(0.3)
Net income (loss)	214.2	160.5	38.4
Net income attributable to non-controlling partner	0.0	0.0	0.0
Net income (loss) attributable to parent	214.2	160.5
Net income (loss) attributable to partners			38.4
Non-Guarantor Subsidiaries | Reportable Legal Entities
Revenues:
Revenues	70.1	0.0	0.0
Costs of product/services sold (exclusive of items shown separately below):
Total costs of products/services sold	0.0	0.0	0.0
Operating expenses and other:
Operations and maintenance	18.8	0.0	0.0
General and administrative	0.0	0.0	0.0
Depreciation, amortization and accretion	30.5	0.0	0.0
Goodwill impairment			0.0
Loss on contingent consideration			57.0
Loss on long-lived assets, net	0.0	0.0	0.0
Gain on acquisition	(209.4)
Total expenses	(160.1)	0.0	57.0
Operating income (loss)	230.2	0.0	(57.0)
Other income (expense):
Earnings from unconsolidated affiliates, net	32.8	53.3	47.8
Interest and debt expense, net	0.1	0.0	0.0
Loss on modification/extinguishment of debt		0.0	0.0
Other income, net			0.0
Other income, net	0.0
Loss from unconsolidated affiliates	0.0	0.0	0.0
Income (loss) before income taxes	263.1
(Provision) benefit for income taxes	0.0
Net income (loss)	263.1	53.3	(9.2)
Net income attributable to non-controlling partner	34.8	16.2	25.3
Net income (loss) attributable to parent	228.3	37.1
Net income (loss) attributable to partners			(34.5)
CMLP
Revenues:
Revenues	3,181.9	3,654.1	3,880.9
Costs of product/services sold (exclusive of items shown separately below):
Total costs of products/services sold	2,544.9	3,129.4	3,374.7
Operating expenses and other:
Operations and maintenance	138.8	125.8	136.0
General and administrative	98.2	83.5	93.1
Depreciation, amortization and accretion	209.9	181.4	202.7
Goodwill impairment			38.8
Loss on contingent consideration			57.0
Loss on long-lived assets, net	6.2	28.6	65.6
Gain on acquisition	(209.4)
Total expenses	243.7	419.3	593.2
Operating income (loss)	393.3	105.4	(87.0)
Other income (expense):
Earnings from unconsolidated affiliates, net	32.8	53.3	47.8
Interest and debt expense, net	(115.4)	(99.2)	(99.4)
Loss on modification/extinguishment of debt		(0.9)	(37.7)
Other income, net			0.8
Other income, net	0.2
Loss from unconsolidated affiliates	0.0	0.0	0.0
Income (loss) before income taxes	310.9
(Provision) benefit for income taxes	(0.3)
Net income (loss)	310.6	58.6	(175.5)
Net income attributable to non-controlling partner	34.8	16.2	25.3
Net income (loss) attributable to parent	$ 275.8	$ 42.4
Net income (loss) attributable to partners			$ (200.8)