Condensed Consolidating Financial Information (Balance Sheet) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Current assets:
Cash	$ 5.2	$ 25.7
Accounts receivable	202.4	242.2
Inventory	20.1	53.7
Total current assets	288.9	376.4
Property, plant and equipment, net	2,932.9	2,909.1
Operating lease, right-of-use assets, net	49.4	53.8
Investment	972.2	980.4
Other non-current assets	4.6	5.5
Total assets	5,177.1	5,349.3
Current liabilities:
Accounts payable	118.1	189.2
Total current liabilities	282.2	357.8
Long-term liabilities:
Long-term debt, less current portion	2,358.9	2,328.3
Other long-term liabilities	280.0	301.6
Deferred income taxes	2.4	2.6
Total liabilities	2,923.5	2,990.3
Interest of non-controlling partner in subsidiary	426.9	426.2
Total partners’ capital	1,826.7	1,932.8
Total liabilities and capital	5,177.1	5,349.3
Eliminations
Current assets:
Cash	0.0	0.0
Accounts receivable	0.0	0.0
Inventory	0.0	0.0
Other	0.0	0.0
Total current assets	0.0	0.0
Property, plant and equipment, net	0.0	0.0
Operating lease, right-of-use assets, net	0.0	0.0
Goodwill and intangible assets, net	0.0	0.0
Investment in consolidated affiliates	(4,392.5)	(4,451.6)
Investment	0.0	0.0
Other non-current assets	0.0	0.0
Total assets	(4,392.5)	(4,451.6)
Current liabilities:
Accounts payable	0.0	0.0
Other current liabilities	0.0	0.0
Total current liabilities	0.0	0.0
Long-term liabilities:
Long-term debt, less current portion	0.0	0.0
Other long-term liabilities	0.0	0.0
Deferred income taxes	0.0	0.0
Total liabilities	0.0	0.0
Interest of non-controlling partner in subsidiary (Note 9)		0.0
Interest of non-controlling partner in subsidiary	0.0
Partners' capital	(4,392.5)	(4,451.6)
Total liabilities and capital	(4,392.5)	(4,451.6)
Parent Company, Crestwood Midstream Partners, LP | Reportable Legal Entities
Current assets:
Cash	4.8	1.8
Accounts receivable	0.0	0.0
Inventory	0.0	0.0
Other	0.0	0.0
Total current assets	4.8	1.8
Property, plant and equipment, net	0.0	0.0
Operating lease, right-of-use assets, net	0.0	0.0
Goodwill and intangible assets, net	0.0	0.0
Investment in consolidated affiliates	4,392.5	4,451.6
Investment	0.0	0.0
Other non-current assets	0.0	0.0
Total assets	4,397.3	4,453.4
Current liabilities:
Accounts payable	0.0	0.0
Other current liabilities	52.2	25.8
Total current liabilities	52.2	25.8
Long-term liabilities:
Long-term debt, less current portion	2,358.9	2,328.3
Other long-term liabilities	0.0	0.0
Deferred income taxes	0.0	0.0
Total liabilities	2,411.1	2,354.1
Interest of non-controlling partner in subsidiary (Note 9)		0.0
Interest of non-controlling partner in subsidiary	0.0
Partners' capital	1,986.2	2,099.3
Total liabilities and capital	4,397.3	4,453.4
Guarantor Subsidiaries | Reportable Legal Entities
Current assets:
Cash	0.0	0.0
Accounts receivable	176.3	229.1
Inventory	20.1	53.7
Other	61.1	54.6
Total current assets	257.5	337.4
Property, plant and equipment, net	2,316.9	2,331.3
Operating lease, right-of-use assets, net	46.7	51.0
Goodwill and intangible assets, net	640.3	650.7
Investment in consolidated affiliates	0.0	0.0
Investment	0.0	0.0
Other non-current assets	2.1	1.9
Total assets	3,263.5	3,372.3
Current liabilities:
Accounts payable	106.9	175.9
Other current liabilities	82.9	123.9
Total current liabilities	189.8	299.8
Long-term liabilities:
Long-term debt, less current portion	0.0	0.0
Other long-term liabilities	169.7	174.8
Deferred income taxes	0.7	0.7
Total liabilities	360.2	475.3
Interest of non-controlling partner in subsidiary (Note 9)		0.0
Interest of non-controlling partner in subsidiary	0.0
Partners' capital	2,903.3	2,897.0
Total liabilities and capital	3,263.5	3,372.3
Non-Guarantor Subsidiaries | Reportable Legal Entities
Current assets:
Cash	0.0	23.6
Accounts receivable	25.9	12.8
Inventory	0.0	0.0
Other	0.1	0.2
Total current assets	26.0	36.6
Property, plant and equipment, net	770.8	736.2
Operating lease, right-of-use assets, net	2.7	2.8
Goodwill and intangible assets, net	288.8	373.4
Investment in consolidated affiliates	0.0	0.0
Investment	972.2	980.4
Other non-current assets	0.5	0.5
Total assets	2,061.0	2,129.9
Current liabilities:
Accounts payable	8.6	10.7
Other current liabilities	27.6	17.6
Total current liabilities	36.2	28.3
Long-term liabilities:
Long-term debt, less current portion	0.0	0.0
Other long-term liabilities	108.7	120.8
Deferred income taxes	0.0	0.0
Total liabilities	144.9	149.1
Interest of non-controlling partner in subsidiary (Note 9)		426.2
Interest of non-controlling partner in subsidiary	426.9
Partners' capital	1,489.2	1,554.6
Total liabilities and capital	2,061.0	2,129.9
Crestwood Midstream Partners LP
Current assets:
Cash	4.8	25.4
Accounts receivable	202.2	241.9
Inventory	20.1	53.7
Other	61.2	54.8
Total current assets	288.3	375.8
Property, plant and equipment, net	3,087.7	3,067.5
Operating lease, right-of-use assets, net	49.4	53.8
Goodwill and intangible assets, net	929.1	1,024.1
Investment in consolidated affiliates	0.0	0.0
Investment	972.2	980.4
Other non-current assets	2.6	2.4
Total assets	5,329.3	5,504.0
Current liabilities:
Accounts payable	115.5	186.6
Other current liabilities	162.7	167.3
Total current liabilities	278.2	353.9
Long-term liabilities:
Long-term debt, less current portion	2,358.9	2,328.3
Other long-term liabilities	278.4	295.6
Deferred income taxes	0.7	0.7
Total liabilities	2,916.2	2,978.5
Interest of non-controlling partner in subsidiary (Note 9)		426.2
Interest of non-controlling partner in subsidiary	426.9
Partners' capital	1,986.2	2,099.3
Total liabilities and capital	$ 5,329.3	$ 5,504.0