Equity Method Investments - Schedule of Equity Method Investments (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	$ 62.2	$ 24.6
(Income) loss from equity affiliates	(82.1)	60.1	$ (3.4)
Equity method investment and financing receivables related to Middlemount
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	62.2	24.6
(Income) loss from equity affiliates	(82.1)	60.1	(9.0)
Other equity method investments
Schedule of Equity Method Investments [Line Items]
Equity Method Investments	0.0	0.0
(Income) loss from equity affiliates	$ 0.0	$ 0.0	$ 5.6