Condensed Consolidating Financial Information (Statements Of Operations) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Income Tax Expense (Benefit)	$ (0.1)	$ 0.3	$ (0.1)	$ 0.3
Revenues	352.7	683.4	1,080.6	1,518.6
Costs of product/services sold	225.7	537.2	760.1	1,232.8
Operating expenses and other:
Operations and maintenance	31.6	34.7	69.2	63.3
General and administrative	29.5	22.3	44.4	59.5
Depreciation, amortization and accretion	61.0	49.3	117.1	89.1
Loss on long-lived assets, net	3.8	0.0	4.8	2.0
Gain on acquisition	0.0	(209.4)	0.0	(209.4)
Goodwill impairment	0.0	0.0	80.3	0.0
Total expenses	125.9	(103.1)	315.8	4.5
Operating income (loss)	1.1	249.3	4.7	281.3
Earnings from unconsolidated affiliates, net	8.4	3.7	13.9	10.6
Interest and debt expense, net	(34.0)	(27.8)	(66.6)	(52.7)
Income (loss) before income taxes	(24.4)	225.3	(47.8)	239.4
Net income (loss)	(24.3)	225.0	(47.7)	239.1
Net income attributable to non-controlling partner in subsidiary	10.2	10.6	20.1	14.6
Net income (loss) attributable to parent	(34.5)	214.4	(67.8)	224.5
Eliminations
Income Tax Expense (Benefit)	0.0	0.0	0.0	0.0
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	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
Gain on acquisition		0.0		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	(11.7)	(250.0)	(26.5)	(301.0)
Income (loss) before income taxes	(11.7)	(250.0)	(26.5)	(301.0)
Net income (loss)	(11.7)	(250.0)	(26.5)	(301.0)
Net income attributable to non-controlling partner in subsidiary	0.0	0.0	0.0	0.0
Net income (loss) attributable to parent	(11.7)	(250.0)	(26.5)	(301.0)
Non-Guarantor Subsidiaries | Reportable Legal Entities
Income Tax Expense (Benefit)	0.0	0.0	0.0	0.0
Revenues	16.2	20.2	43.7	20.2
Costs of product/services sold	0.2	0.0	0.2	0.0
Operating expenses and other:
Operations and maintenance	5.1	7.2	10.9	7.2
General and administrative	0.0	0.0	0.0	0.0
Depreciation, amortization and accretion	14.3	9.7	26.1	9.7
Loss on long-lived assets, net	1.8		1.8	0.0
Gain on acquisition		209.4		209.4
Goodwill impairment			80.3
Total expenses	21.2	(192.5)	119.1	(192.5)
Operating income (loss)	(5.2)	212.7	(75.6)	212.7
Earnings from unconsolidated affiliates, net	8.4	3.7	13.9	10.6
Interest and debt expense, net	0.0	0.0	0.0	0.0
Loss from unconsolidated affiliates	0.0	0.0	0.0	0.0
Income (loss) before income taxes	3.2	216.4	(61.7)	223.3
Net income (loss)	3.2	216.4	(61.7)	223.3
Net income attributable to non-controlling partner in subsidiary	10.2	10.6	20.1	14.6
Net income (loss) attributable to parent	(7.0)	205.8	(81.8)	208.7
Crestwood Midstream Partners LP
Income Tax Expense (Benefit)	(0.2)	0.3	(0.2)	0.3
Revenues	352.7	683.4	1,080.6	1,518.6
Costs of product/services sold	225.7	537.2	760.1	1,232.8
Operating expenses and other:
Operations and maintenance	31.6	34.7	69.2	63.3
General and administrative	28.4	20.9	41.9	56.9
Depreciation, amortization and accretion	64.6	52.7	124.2	96.1
Loss on long-lived assets, net	3.8		4.8	2.0
Gain on acquisition		209.4		209.4
Goodwill impairment			80.3
Total expenses	128.4	(101.1)	320.4	8.9
Operating income (loss)	(1.4)	247.3	0.1	276.9
Earnings from unconsolidated affiliates, net	8.4	3.7	13.9	10.6
Interest and debt expense, net	(34.0)	(27.8)	(66.6)	(52.7)
Loss from unconsolidated affiliates	0.0	0.0	0.0	0.0
Income (loss) before income taxes	(27.0)	223.2	(52.6)	234.8
Net income (loss)	(26.8)	222.9	(52.4)	234.5
Net income attributable to non-controlling partner in subsidiary	10.2	10.6	20.1	14.6
Net income (loss) attributable to parent	(37.0)	212.3	(72.5)	219.9
Guarantor Subsidiaries | Reportable Legal Entities
Income Tax Expense (Benefit)	(0.2)	0.3	(0.2)	0.3
Revenues	336.5	663.2	1,036.9	1,498.4
Costs of product/services sold	225.5	537.2	759.9	1,232.8
Operating expenses and other:
Operations and maintenance	26.5	27.5	58.3	56.1
General and administrative	13.6	11.2	9.2	28.5
Depreciation, amortization and accretion	50.3	43.0	98.1	86.4
Loss on long-lived assets, net	2.0		3.0	2.0
Gain on acquisition		0.0		0.0
Goodwill impairment			0.0
Total expenses	92.4	81.7	168.6	173.0
Operating income (loss)	18.6	44.3	108.4	92.6
Earnings from unconsolidated affiliates, net	0.0	0.0	0.0	0.0
Interest and debt expense, net	(0.1)	0.2	(0.3)	0.0
Loss from unconsolidated affiliates	0.0	0.0	0.0	0.0
Income (loss) before income taxes	18.5	44.5	108.1	92.6
Net income (loss)	18.7	44.2	108.3	92.3
Net income attributable to non-controlling partner in subsidiary	0.0	0.0	0.0	0.0
Net income (loss) attributable to parent	18.7	44.2	108.3	92.3
Parent Company, Crestwood Midstream Partners, LP | Reportable Legal Entities
Income Tax Expense (Benefit)	0.0	0.0	0.0	0.0
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	14.8	9.7	32.7	28.4
Depreciation, amortization and accretion	0.0	0.0	0.0	0.0
Loss on long-lived assets, net	0.0		0.0	0.0
Gain on acquisition		0.0		0.0
Goodwill impairment			0.0
Total expenses	14.8	9.7	32.7	28.4
Operating income (loss)	(14.8)	(9.7)	(32.7)	(28.4)
Earnings from unconsolidated affiliates, net	0.0	0.0	0.0	0.0
Interest and debt expense, net	(33.9)	(28.0)	(66.3)	(52.7)
Loss from unconsolidated affiliates	11.7	250.0	26.5	301.0
Income (loss) before income taxes	(37.0)	212.3	(72.5)	219.9
Net income (loss)	(37.0)	212.3	(72.5)	219.9
Net income attributable to non-controlling partner in subsidiary	0.0	0.0	0.0	0.0
Net income (loss) attributable to parent	$ (37.0)	$ 212.3	$ (72.5)	$ 219.9