v3.25.4
Workers' Compensation and Pneumoconiosis (Black Lung) Obligations (Narrative) (Details) - USD ($)
$ in Millions
12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
May 01, 2024
Workers' Compensation [Line Items]        
Incurred claims, premium expenses and administrative fees related to workers compensation $ 43.9 $ 40.2 $ 35.0  
Other Non-current Liabilities [Member]        
Workers' Compensation [Line Items]        
Workers' compensation liability 38.5 34.4    
Workers' Compensation Insurance [Member]        
Workers' Compensation [Line Items]        
Workers' compensation insurance, claims per occurrence 0.5      
Workers' compensation insurance, aggregate claims       $ 29.1
Collateral deposit 73.2      
Incurred claims, premium expenses and administrative fees related to workers compensation 8.9 8.9 $ 16.3  
Workers' compensation liability $ 43.1 $ 39.1