Investments in Unconsolidated Affiliates Summarized Financial Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Apr. 09, 2019
Schedule of Equity Method Investments [Line Items]
Operating Revenues	$ 66.0	$ 82.1
Operating Expenses	67.9	62.4
Net Income (Loss)	(1.1)	19.1
Jackalope Gas Gathering Services, L.L.C.
Schedule of Equity Method Investments [Line Items]
Amortization	0.1
Stagecoach Gas Services LLC
Schedule of Equity Method Investments [Line Items]
Operating Revenues	37.7	40.3
Operating Expenses	19.4	20.2
Net Income (Loss)	18.4	20.2
Other Equity Method Investments
Schedule of Equity Method Investments [Line Items]
Operating Revenues	28.3	41.8
Operating Expenses	48.5	42.2
Net Income (Loss)	(19.5)	(1.1)
Tres Palacios Holdings LLC
Schedule of Equity Method Investments [Line Items]
Amortization	$ 0.3	0.3
Powder River Basin Industrial Complex, LLC
Schedule of Equity Method Investments [Line Items]
Amortization		$ 0.1
Crestwood Niobrara LLC | Williams Partners LP
Schedule of Equity Method Investments [Line Items]
Business Acquisition, Percentage Of Additional Voting Interests Acquired			50.00%