XML 29 R16.htm IDEA: XBRL DOCUMENT v3.24.2.u1
Property, Plant, Equipment and Mine Development
 6 Months Ended
Jun. 30, 2024
Property, Plant and Equipment [Abstract]  
Property, Plant, Equipment and Mine Development Property, Plant, Equipment and Mine Development
The composition of property, plant, equipment and mine development, net, as of June 30, 2024 and December 31, 2023 is set forth in the table below:
June 30, 2024December 31, 2023
(Dollars in millions)
Land and coal interests$2,624.0 $2,475.2 
Buildings and improvements647.7 647.6 
Machinery and equipment1,943.5 1,787.6 
Less: Accumulated depreciation, depletion and amortization(2,212.1)(2,066.3)
Property, plant, equipment and mine development, net$3,003.1 $2,844.1 
At-Risk Assets
The Company identified certain assets with an aggregate carrying value of approximately $214 million at June 30, 2024 in its Other U.S. Thermal segment whose recoverability is most sensitive to customer concentration risk.