Equity Method Investments (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Schedule of Equity Method Investments [Line Items]
Equity method investments	$ 48.4		$ 49.6
Loss (income) from equity affiliates	3.7	$ (1.8)
Middlemount Mine
Schedule of Equity Method Investments [Line Items]
Equity method investments	40.1		42.5
Loss (income) from equity affiliates	(0.4)	2.6
R3 Renewables
Schedule of Equity Method Investments [Line Items]
Equity method investments	8.3		$ 7.1
Loss (income) from equity affiliates	$ (3.3)	$ (0.8)