Investment in Unconsolidated Affiliates Summarized Income Statement of Equity Method Investment (Details) - USD ($) $ in Millions	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
Schedule of Equity Method Investments [Line Items]
Operating revenues	$ 702.1			$ 755.4			$ 1,636.9	$ 1,759.1
Operating Income (Loss)	258.0			274.3			439.7	434.0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	177.4	$ 85.9	$ (491.8)	250.9	$ 100.2	$ 47.1	(228.5)	398.2
Equity Method Investment, Nonconsolidated Investee or Group of Investees [Member]
Schedule of Equity Method Investments [Line Items]
Operating revenues	596.0			699.0			1,759.0	2,229.0
Cost of Revenue	250.0			263.0			653.0	958.0
Operating Income (Loss)	100.0			175.0			326.0	507.0
Net Income (Loss), Including Portion Attributable to Noncontrolling Interest	$ (173.0)			$ 123.0			$ (35.0)	$ 351.1