Inventories (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Inventory [Line Items]
Materials and supplies, net	$ 161.4	$ 153.0
Raw coal	125.8	105.6
Saleable coal	117.1	93.2
Inventories, net	$ 404.3	$ 351.8

Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer.

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