Investments in Unconsolidated Affiliates Summarized Financial Information (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Apr. 09, 2019
Schedule of Equity Method Investments [Line Items]
Revenues	$ 352.7	$ 683.4	$ 1,080.6	$ 1,518.6
Operating Expenses	125.9	(103.1)	315.8	4.5
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ (24.3)	$ 225.0	(47.7)	239.1
Jackalope Gas Gathering Services, L.L.C.
Schedule of Equity Method Investments [Line Items]
Amortization			0.1
Tres Palacios Holdings LLC
Schedule of Equity Method Investments [Line Items]
Amortization			0.6	0.3
Powder River Basin Industrial Complex, LLC
Schedule of Equity Method Investments [Line Items]
Amortization				0.2
Crestwood Niobrara LLC | Williams Partners LP
Schedule of Equity Method Investments [Line Items]
Additional voting rights acquired					50.00%
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Schedule of Equity Method Investments [Line Items]
Revenues			129.1	134.5
Operating Expenses			115.0	102.6
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest			15.2	31.0
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member] | Stagecoach Gas Services LLC
Schedule of Equity Method Investments [Line Items]
Revenues			75.6	79.1
Operating Expenses			38.9	40.4
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest			36.8	38.9
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member] | Other Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Revenues			53.5	55.4
Operating Expenses			76.1	62.2
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest			$ (21.6)	$ (7.9)