XML 252 R85.htm IDEA: XBRL DOCUMENT v3.24.0.1
Leases - Supplemental Balance Sheet Information (Details) - USD ($)
$ in Millions
Dec. 31, 2023
Dec. 31, 2022
Dec. 31, 2021
Operating leases:      
Operating lease right-of-use assets $ 61.9 $ 26.9 $ 35.5
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List] Accounts Payable and Accrued Liabilities, Current Accounts Payable and Accrued Liabilities, Current  
Accounts payable and accrued expenses $ 17.3 $ 16.8  
Operating lease liabilities, less current portion 47.7 11.0  
Total operating lease liabilities 65.0 27.8  
Finance leases:      
Property, plant, equipment and mine development 34.3 36.1  
Accumulated depreciation (15.4) (12.6)  
Property, plant, equipment and mine development, net $ 18.9 $ 23.5  
Finance Lease, Liability, Statement of Financial Position [Extensible Enumeration] Long-Term Debt and Lease Obligation Long-Term Debt and Lease Obligation  
Total finance lease liabilities $ 22.3 $ 23.6  
Weighted average remaining lease term (years)      
Operating leases 4 years 7 months 6 days    
Finance leases 2 years 3 months 18 days    
Weighted average discount rate      
Operating leases 6.80%    
Finance leases 6.80%    
Operating Leased Assets [Line Items]      
Operating lease liabilities $ 17.3 16.8  
Long-term Debt      
Finance leases:      
Current portion of long-term debt 13.5 13.2  
Long-term debt, less current portion 8.8 10.4  
Operating Leased Assets [Line Items]      
Long-term debt, less current portion 8.8 10.4  
Current portion of long-term debt $ 13.5 $ 13.2