Condensed Consolidating Financial Information (Statements Of Operations) (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended		9 Months Ended
	Jun. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues		$ 955.6	$ 587.6	$ 2,634.0	$ 1,725.5
Total costs of products/services sold		858.5	466.7	2,271.6	1,280.1
Expenses:
Operations and maintenance		35.5	33.1	103.4	119.9
General and administrative		22.5	18.3	71.6	70.2
Depreciation, amortization and accretion		48.1	50.3	145.2	177.0
Gain (loss) on long-lived assets		(6.3)	(2.1)	(6.3)	(34.8)
Goodwill impairment		0.0	0.0	0.0	(109.7)
Operating loss		(15.3)	17.1	35.9	(66.2)
Earnings from unconsolidated affiliates, net		11.5	13.4	29.2	26.1
Interest and debt expense, net		(24.2)	(27.5)	(74.8)	(97.9)
Gains (Losses) on Extinguishment of Debt	$ (10.0)	0.0	0.0	(37.7)	10.0
Loss before income taxes		(27.8)	3.2	(47.0)	(127.6)
Provision for income taxes		(0.1)	(0.2)	0.0	(0.2)
Net income (loss)		(27.9)	3.0	(47.0)	(127.8)
Net income attributable to non-controlling partners in subsidiaries		6.4	6.1	18.8	18.0
Net income (loss) attributable to parent		(34.3)	(3.1)	(65.8)	(145.8)
Eliminations
Revenues		0.0	0.0	0.0	0.0
Total costs of products/services sold		0.0	0.0	0.0	0.0
Expenses:
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
Costs and Expenses		0.0	0.0	0.0	0.0
Gain (loss) on long-lived assets		0.0	0.0	0.0	0.0
Goodwill impairment					0.0
Operating 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
Gains (Losses) on Extinguishment of Debt				0.0	0.0
Loss from unconsolidated affiliates		(3.2)	(35.3)	(90.7)	6.2
Loss before income taxes		(3.2)
Provision for income taxes		0.0
Net income (loss)		(3.2)	(35.3)	(90.7)	6.2
Net income attributable to non-controlling partners in subsidiaries		0.0	0.0	0.0	0.0
Net income (loss) attributable to parent		(3.2)	(35.3)	(90.7)	6.2
Non-Guarantor Subsidiaries | Reportable Legal Entities
Revenues		0.0	0.0	0.0	0.0
Total costs of products/services sold		0.0	0.0	0.0	0.0
Expenses:
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
Costs and Expenses		0.0	0.0	0.0	0.0
Gain (loss) on long-lived assets		0.0	0.0	0.0	0.0
Goodwill impairment					0.0
Operating loss		0.0	0.0	0.0	0.0
Earnings from unconsolidated affiliates, net		11.5	13.4	29.2	26.1
Interest and debt expense, net		0.0	0.0	0.0	0.0
Gains (Losses) on Extinguishment of Debt				0.0	0.0
Loss from unconsolidated affiliates		0.0	0.0	0.0	0.0
Loss before income taxes		11.5
Provision for income taxes		0.0
Net income (loss)		11.5	13.4	29.2	26.1
Net income attributable to non-controlling partners in subsidiaries		6.4	6.1	18.8	18.0
Net income (loss) attributable to parent		5.1	7.3	10.4	8.1
Crestwood Midstream Partners LP
Revenues		955.6	587.6	2,634.0	1,725.5
Total costs of products/services sold		858.5	466.7	2,271.6	1,280.1
Expenses:
Operations and maintenance		35.5	33.6	103.4	116.7
General and administrative		21.4	17.3	69.0	67.5
Depreciation, amortization and accretion		50.9	53.2	153.5	185.2
Costs and Expenses		107.8	104.1	325.9	369.4
Gain (loss) on long-lived assets			(2.1)		(34.8)
Goodwill impairment					(109.7)
Operating loss		(17.0)	14.7	30.2	(68.5)
Earnings from unconsolidated affiliates, net		11.5	13.4	29.2	26.1
Interest and debt expense, net		(24.2)	(27.5)	(74.8)	(97.9)
Gains (Losses) on Extinguishment of Debt				(37.7)	10.0
Loss from unconsolidated affiliates		0.0	0.0	0.0	0.0
Loss before income taxes		(29.7)
Provision for income taxes		(0.1)
Net income (loss)		(29.8)	0.6	(53.1)	(130.3)
Net income attributable to non-controlling partners in subsidiaries		6.4	6.1	18.8	18.0
Net income (loss) attributable to parent		(36.2)	(5.5)	(71.9)	(148.3)
Guarantor Subsidiaries | Reportable Legal Entities
Revenues		955.6	587.6	2,634.0	1,725.5
Total costs of products/services sold		858.5	466.7	2,271.6	1,280.1
Expenses:
Operations and maintenance		35.5	33.6	103.4	116.7
General and administrative		6.2	4.0	18.9	13.3
Depreciation, amortization and accretion		50.9	53.2	153.5	185.2
Costs and Expenses		92.6	90.8	275.8	315.2
Gain (loss) on long-lived assets		(6.3)	(2.1)	(6.3)	(34.8)
Goodwill impairment					(109.7)
Operating loss		(1.8)	28.0	80.3	(14.3)
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
Gains (Losses) on Extinguishment of Debt				0.0	0.0
Loss from unconsolidated affiliates		0.0	0.0	0.0	0.0
Loss before income taxes		(1.8)
Provision for income taxes		(0.1)
Net income (loss)		(1.9)	28.0	80.3	(14.3)
Net income attributable to non-controlling partners in subsidiaries		0.0	0.0	0.0	0.0
Net income (loss) attributable to parent		(1.9)	28.0	80.3	(14.3)
Parent Company, Crestwood Midstream Partners, LP | Reportable Legal Entities
Revenues		0.0	0.0	0.0	0.0
Total costs of products/services sold		0.0	0.0	0.0	0.0
Expenses:
Operations and maintenance		0.0	0.0	0.0	0.0
General and administrative		15.2	13.3	50.1	54.2
Depreciation, amortization and accretion		0.0	0.0	0.0	0.0
Costs and Expenses		15.2	13.3	50.1	54.2
Gain (loss) on long-lived assets		0.0	0.0	0.0	0.0
Goodwill impairment					0.0
Operating loss		(15.2)	(13.3)	(50.1)	(54.2)
Earnings from unconsolidated affiliates, net		0.0	0.0	0.0	0.0
Interest and debt expense, net		(24.2)	(27.5)	(74.8)	(97.9)
Gains (Losses) on Extinguishment of Debt				(37.7)	10.0
Loss from unconsolidated affiliates		3.2	35.3	90.7	(6.2)
Loss before income taxes		(36.2)
Provision for income taxes		0.0
Net income (loss)		(36.2)	(5.5)	(71.9)	(148.3)
Net income attributable to non-controlling partners in subsidiaries		0.0	0.0	0.0	0.0
Net income (loss) attributable to parent		$ (36.2)	$ (5.5)	$ (71.9)	$ (148.3)