Equity Method Investments (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022	Dec. 31, 2022
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 40.9		$ 40.9		$ 34.1
Income (Loss) from Equity Method Investments	(2.3)	$ (48.7)	(4.1)	$ (93.4)
Middlemount Mine
Schedule of Equity Method Investments [Line Items]
Equity method investments	33.1		33.1		27.1
Income (Loss) from Equity Method Investments	4.1	49.5	6.7	95.2
R3 Renewables
Schedule of Equity Method Investments [Line Items]
Equity method investments	7.8		7.8		$ 7.0
Income (Loss) from Equity Method Investments	$ (1.8)	$ (0.8)	$ (2.6)	$ (1.8)