Segment Information - Segment Results (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Reportable segment results
Revenue	$ 1,364.0	$ 691.4
Adjusted EBITDA	390.6	327.5
Seaborne Thermal Mining
Reportable segment results
Revenue	346.5	251.2
Adjusted EBITDA	164.0	90.5
Seaborne Metallurgical Mining
Reportable segment results
Revenue	288.4	321.3
Adjusted EBITDA	90.8	181.0
Powder River Basin Mining
Reportable segment results
Revenue	305.3	251.2
Adjusted EBITDA	35.8	7.6
Other U.S. Thermal Mining
Reportable segment results
Revenue	249.4	203.1
Adjusted EBITDA	64.2	50.0
Corporate and Other (1)
Reportable segment results
Revenue	174.4	(335.4)
Adjusted EBITDA	$ 35.8	$ (1.6)