Investments in Unconsolidated Affiliates Table (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Oct. 31, 2017	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Apr. 30, 2019	Apr. 09, 2019	Apr. 08, 2019	Jul. 01, 2018
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated affiliates		$ 980.4	$ 1,188.2
Earnings from unconsolidated affiliates, net		32.8	53.3	$ 47.8
Distributions		75.2	103.0	107.6
Contributions				127.4
Contributions		61.3	64.4	58.0
Current Assets		78.2	127.1
Non-Current Assets		2,351.0	2,755.7
Current Liabilities		41.2	38.4
Non-Current Liabilities		194.7	225.2
Members’ Equity		2,193.3	2,619.2
Operating Revenues		283.7	370.5	350.4
Operating Expenses		209.5	242.1	221.3
Net Income (Loss)		$ 74.6	133.4	130.0
Stagecoach Gas Services LLC
Schedule of Equity Method Investments [Line Items]
Equity method ownership percentage		50.00%						50.00%
Investments in unconsolidated affiliates		$ 814.4	830.4
Earnings from unconsolidated affiliates, net		34.2	29.3	25.3
Distributions		52.3	48.7	47.3
Contributions		2.1	0.0	0.8
Current Assets		50.6	50.1
Non-Current Assets		1,686.3	1,725.1
Current Liabilities		3.9	4.2
Non-Current Liabilities		1.5	0.9
Members’ Equity		1,731.5	1,770.1
Operating Revenues		163.8	171.4	168.6
Operating Expenses		83.6	79.3	77.7
Net Income (Loss)		80.6	92.1	91.1
Difference between carrying amount and underlying equity		51.3
Crestwood Permian Basin LLC
Schedule of Equity Method Investments [Line Items]
Operating Revenues		64.8	82.2	87.3
Operating Expenses		76.0	81.3	74.1
Net Income (Loss)		(11.1)	5.7	14.1
Difference between carrying amount and underlying equity		$ 11.5
Jackalope Gas Gathering Services, LLC
Schedule of Equity Method Investments [Line Items]
Equity method ownership percentage		0.00%			50.00%	50.00%	50.00%
Investments in unconsolidated affiliates		$ 0.0	210.2			$ 226.7
Earnings from unconsolidated affiliates, net		3.7	18.1	10.5
Distributions		11.6	32.4	26.3
Operating Revenues		55.1	116.9	94.5
Operating Expenses		49.9	81.5	69.5
Net Income (Loss)		5.1	35.6	24.8
Amortization		0.1	0.1	0.1
Other Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Current Assets		11.7	59.3
Non-Current Assets		277.9	658.0
Current Liabilities		21.0	17.4
Non-Current Liabilities		121.1	129.6
Members’ Equity		$ 147.5	570.3
Crestwood Permian Basin Holdings LLC
Schedule of Equity Method Investments [Line Items]
Equity method ownership percentage		50.00%
Investments in unconsolidated affiliates		$ 121.8	104.3
Earnings from unconsolidated affiliates, net		(5.8)	4.4	8.4
Distributions	$ 18.9	5.0	14.7	23.4
Contributions				117.5
Contributions		28.3	12.6
Current Assets		15.9	17.7
Non-Current Assets		386.8	372.6
Current Liabilities		16.3	16.8
Non-Current Liabilities		72.1	94.7
Members’ Equity		$ 314.3	278.8
Tres Palacios Holdings LLC
Schedule of Equity Method Investments [Line Items]
Equity method ownership percentage		50.01%
Investments in unconsolidated affiliates		$ 35.9	35.0
Earnings from unconsolidated affiliates, net		0.9	0.0	2.2
Distributions		6.3	5.3	9.0
Contributions		6.3	2.5	5.6
Difference between carrying amount and underlying equity		24.0
Amortization		$ 1.3	1.3	1.3
Powder River Basin Industrial Complex, LLC
Schedule of Equity Method Investments [Line Items]
Equity method ownership percentage		50.01%
Investments in unconsolidated affiliates		$ 8.3	8.3
Earnings from unconsolidated affiliates, net		(0.2)	1.5	1.4
Distributions		0.0	1.9	1.6
Contributions		0.2	0.2	0.0
Difference between carrying amount and underlying equity		5.5
Amortization		0.4	0.5	0.6
Crestwood Niobrara LLC | Jackalope Gas Gathering Services, LLC
Schedule of Equity Method Investments [Line Items]
Contributions		$ 24.4	$ 49.1	$ 3.5
Crestwood Niobrara LLC | Williams Partners LP
Schedule of Equity Method Investments [Line Items]
Additional voting interest acquired						50.00%