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Commitments and Contingent Liabilities - Schedule of Black Lung Benefit Liabilities (Details)
$ in Millions
 12 Months Ended
Dec. 31, 2022
USD ($)
claim
Sep. 30, 2023
USD ($)
Loss Contingencies [Line Items]    
Current portion of black lung liability $ 5.9 $ 5.9
Black lung Benefit    
Loss Contingencies [Line Items]    
Discount rate 4.90%  
Active claims | claim 332  
Total black lung liability discounted (dollars in millions) $ 58.1  
Total black lung liability, undiscounted (dollars in millions) 88.4  
Increase in black lung expense 1.1  
Current portion of black lung liability $ 5.9 $ 5.9