Investments in Unconsolidated Affiliates Distributions and Contributions (Details) - USD ($) $ in Millions	1 Months Ended	6 Months Ended
	Jul. 31, 2020	Jun. 30, 2020	Jun. 30, 2019
Schedule of Equity Method Investments [Line Items]
Proceeds from equity method investments		$ 38.2	$ 41.1
Payments to acquire equity method investments		6.0	40.9
Payments to Acquire Equity Method Investments Cash and Noncash Consideration			40.9
Stagecoach Gas Services LLC
Schedule of Equity Method Investments [Line Items]
Proceeds from equity method investments		30.0	25.4
Payments to acquire equity method investments		0.0	0.0
Jackalope Gas Gathering Services, L.L.C.
Schedule of Equity Method Investments [Line Items]
Proceeds from equity method investments		0.0	11.6
Payments to acquire equity method investments		0.0	24.4
Crestwood Permian Basin Holdings LLC
Schedule of Equity Method Investments [Line Items]
Proceeds from equity method investments		6.7	2.9
Payments to acquire equity method investments		0.0	10.0
Tres Palacios Holdings LLC
Schedule of Equity Method Investments [Line Items]
Proceeds from equity method investments		1.4	1.2
Payments to acquire equity method investments		6.0	6.3
Powder River Basin Industrial Complex, LLC
Schedule of Equity Method Investments [Line Items]
Proceeds from equity method investments		0.1	0.0
Payments to acquire equity method investments		$ 0.0	$ 0.2
Subsequent Event | Stagecoach Gas Services LLC
Schedule of Equity Method Investments [Line Items]
Proceeds from equity method investments	$ 14.5
Subsequent Event | Crestwood Permian Basin Holdings LLC
Schedule of Equity Method Investments [Line Items]
Proceeds from equity method investments	1.8
Subsequent Event | Tres Palacios Holdings LLC
Schedule of Equity Method Investments [Line Items]
Proceeds from equity method investments	$ 3.0