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Inventories (Tables)
12 Months Ended
Dec. 31, 2021
Inventory Disclosure [Abstract]  
Inventories
Inventories as of December 31, 2021 and December 31, 2020 consisted of the following:
December 31,
 20212020
 (Dollars in millions)
Materials and supplies$102.1 $102.6 
Raw coal54.6 70.5 
Saleable coal70.0 88.5 
Inventories$226.7 $261.6