Investments in Unconsolidated Affiliates (Distributions and Contributions) (Details) - USD ($) $ in Millions	1 Months Ended		9 Months Ended
	Oct. 31, 2021	Jul. 31, 2021	Sep. 30, 2021	Sep. 30, 2020
Schedule of Equity Method Investments [Line Items]
Proceeds from equity method investments			$ 663.0	$ 57.6
Payments to acquire equity method investments			10.2	6.0
Stagecoach Gas Services LLC
Schedule of Equity Method Investments [Line Items]
Proceeds from equity method investments		$ 613.9	640.9	44.5
Payments to acquire equity method investments			0.0	0.0
Transaction costs		3.0
Payment for contingent consideration		$ 40.0	57.0
Crestwood Permian Basin Holdings LLC
Schedule of Equity Method Investments [Line Items]
Proceeds from equity method investments			8.9	8.5
Payments to acquire equity method investments			3.3	0.0
Tres Palacios Holdings LLC
Schedule of Equity Method Investments [Line Items]
Proceeds from equity method investments			13.1	4.4
Payments to acquire equity method investments			6.9	6.0
Powder River Basin Industrial Complex, LLC
Schedule of Equity Method Investments [Line Items]
Proceeds from equity method investments			0.1	0.2
Payments to acquire equity method investments			$ 0.0	$ 0.0
Subsequent Event | Crestwood Permian Basin Holdings LLC
Schedule of Equity Method Investments [Line Items]
Proceeds from equity method investments	$ 7.4
Subsequent Event | Tres Palacios Holdings LLC
Schedule of Equity Method Investments [Line Items]
Proceeds from equity method investments	$ 2.4