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Inventories (Tables)
3 Months Ended
Mar. 31, 2021
Inventory Disclosure [Abstract]  
Schedule of Inventories
Inventories as of March 31, 2021 and December 31, 2020 consisted of the following:
March 31, 2021December 31, 2020
 (Dollars in millions)
Materials and supplies$104.3 $102.6 
Raw coal52.4 70.5 
Saleable coal84.7 88.5 
Total$241.4 $261.6