Condensed Consolidating Financial Information (Statements Of Operations) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Revenues	$ 727.9	$ 835.2
Costs of product/services sold	534.4	695.6
Operating expenses and other:
Operations and maintenance	37.6	28.6
General and administrative	14.9	37.2
Depreciation, amortization and accretion	56.1	39.8
Loss on long-lived assets, net	1.0	2.0
Goodwill, Impairment Loss	(80.3)	0.0
Total expenses	189.9	107.6
Operating income (loss)	3.6	32.0
Earnings from unconsolidated affiliates, net	5.5	6.9
Interest and debt expense, net	(32.6)	(24.9)
Net income (loss)	(23.4)	14.1
Net income attributable to non-controlling partner in subsidiary	9.9	4.0
Net income (loss) attributable to parent	(33.3)	10.1
Eliminations
Revenues	0.0	0.0
Costs of product/services sold	0.0	0.0
Operating expenses and other:
Operations and maintenance	0.0	0.0
General and administrative	0.0	0.0
Depreciation, amortization and accretion	0.0	0.0
Loss on long-lived assets, net	0.0	0.0
Goodwill, Impairment Loss	0.0
Total expenses	0.0	0.0
Operating income (loss)	0.0	0.0
Earnings from unconsolidated affiliates, net	0.0	0.0
Interest and debt expense, net	0.0	0.0
Loss from unconsolidated affiliates	(14.8)	(51.0)
Net income (loss)	(14.8)	(51.0)
Net income attributable to non-controlling partner in subsidiary	0.0	0.0
Net income (loss) attributable to parent	(14.8)	(51.0)
Non-Guarantor Subsidiaries | Reportable Legal Entities
Revenues	27.5	0.0
Costs of product/services sold	0.0	0.0
Operating expenses and other:
Operations and maintenance	5.8	0.0
General and administrative	0.0	0.0
Depreciation, amortization and accretion	11.8	0.0
Loss on long-lived assets, net	0.0	0.0
Goodwill, Impairment Loss	(80.3)
Total expenses	97.9	0.0
Operating income (loss)	(70.4)	0.0
Earnings from unconsolidated affiliates, net	5.5	6.9
Interest and debt expense, net	0.0	0.0
Loss from unconsolidated affiliates	0.0	0.0
Net income (loss)	(64.9)	6.9
Net income attributable to non-controlling partner in subsidiary	9.9	4.0
Net income (loss) attributable to parent	(74.8)	2.9
Crestwood Midstream Partners LP
Revenues	727.9	835.2
Costs of product/services sold	534.4	695.6
Operating expenses and other:
Operations and maintenance	37.6	28.6
General and administrative	13.5	36.0
Depreciation, amortization and accretion	59.6	43.4
Loss on long-lived assets, net	1.0	2.0
Goodwill, Impairment Loss	(80.3)
Total expenses	192.0	110.0
Operating income (loss)	1.5	29.6
Earnings from unconsolidated affiliates, net	5.5	6.9
Interest and debt expense, net	(32.6)	(24.9)
Loss from unconsolidated affiliates	0.0	0.0
Net income (loss)	(25.6)	11.6
Net income attributable to non-controlling partner in subsidiary	9.9	4.0
Net income (loss) attributable to parent	(35.5)	7.6
Guarantor Subsidiaries | Reportable Legal Entities
Revenues	700.4	835.2
Costs of product/services sold	534.4	695.6
Operating expenses and other:
Operations and maintenance	31.8	28.6
General and administrative	(4.4)	17.3
Depreciation, amortization and accretion	47.8	43.4
Loss on long-lived assets, net	1.0	2.0
Goodwill, Impairment Loss	0.0
Total expenses	76.2	91.3
Operating income (loss)	89.8	48.3
Earnings from unconsolidated affiliates, net	0.0	0.0
Interest and debt expense, net	(0.2)	(0.2)
Loss from unconsolidated affiliates	0.0	0.0
Net income (loss)	89.6	48.1
Net income attributable to non-controlling partner in subsidiary	0.0	0.0
Net income (loss) attributable to parent	89.6	48.1
Parent Company, Crestwood Midstream Partners, LP | Reportable Legal Entities
Revenues	0.0	0.0
Costs of product/services sold	0.0	0.0
Operating expenses and other:
Operations and maintenance	0.0	0.0
General and administrative	17.9	18.7
Depreciation, amortization and accretion	0.0	0.0
Loss on long-lived assets, net	0.0	0.0
Goodwill, Impairment Loss	0.0
Total expenses	17.9	18.7
Operating income (loss)	(17.9)	(18.7)
Earnings from unconsolidated affiliates, net	0.0	0.0
Interest and debt expense, net	(32.4)	(24.7)
Loss from unconsolidated affiliates	14.8	51.0
Net income (loss)	(35.5)	7.6
Net income attributable to non-controlling partner in subsidiary	0.0	0.0
Net income (loss) attributable to parent	$ (35.5)	$ 7.6