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Commitments and Contingencies (Details) - USD ($)
$ in Millions
 1 Months Ended 3 Months Ended 9 Months Ended
Jan. 31, 2024
Mar. 31, 2024
Sep. 30, 2024
Dec. 31, 2023
Other Commitments [Line Items]        
Restricted cash, long-term     $ 8.5 $ 8.5
Supply agreement performance bond     3.7  
Contract with customer, liability     1.3  
Tinuum Group, LLC        
Other Commitments [Line Items]        
Liabilities assumed   $ 1.7 $ 1.7  
Tinuum Group, LLC        
Other Commitments [Line Items]        
Limited guarantees (as percent)     50.00%  
Minimum | Deliveries in First Quarter 2025        
Other Commitments [Line Items]        
Construction contract estimated costs $ 75.0      
Maximum | Deliveries in First Quarter 2025        
Other Commitments [Line Items]        
Construction contract estimated costs $ 80.0      
Five Forks Mine        
Other Commitments [Line Items]        
Surety bond amount     $ 7.5  
Corbin Facilities        
Other Commitments [Line Items]        
Surety bond amount     3.0  
West Virginia ("Mine 4")        
Other Commitments [Line Items]        
Surety bond amount     0.7  
Restricted cash, long-term     $ 0.4