v3.26.1
Long-term debt - Revolving Credit Facility - Additional Information (Details) - USD ($)
$ in Millions
6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Long-term debt    
Borrowings on credit facilities $ 283.7 $ 306.3
Kronos Worldwide    
Long-term debt    
Revolving credit facility 28.2  
Kronos Worldwide | Global Revolver Credit Facility    
Long-term debt    
Revolving credit facility 28.2  
Line of credit maximum borrowing capacity 350.0  
Borrowings on credit facilities 280.2  
Repayment of credit facility $ 252.0  
Debt instrument, Interest rate during period 4.90%  
Debt instrument, Interest rate at period end 5.30%  
Amount available for borrowing $ 261.0