v3.25.1
RELATED PARTY TRANSACTIONS: (Details)
$ in Millions
 3 Months Ended 12 Months Ended
Mar. 31, 2025
USD ($)
Mar. 31, 2024
USD ($)
Dec. 31, 2020
MWh
Dec. 31, 2012
item
MW
Dec. 31, 2024
USD ($)
Dec. 31, 2014
item
RELATED PARTY TRANSACTIONS:            
Related parties receivable current: $ 15.0       $ 13.5  
Affiliates            
RELATED PARTY TRANSACTIONS:            
Related parties receivable current: 15.0       13.5  
Other accrued liabilities 65.6       49.2  
Total purchases 106.2 $ 103.2        
Total sales $ 0.8 0.8        
Affiliates | Equity investment in affiliate            
RELATED PARTY TRANSACTIONS:            
Ownership percentage 44.20%          
Affiliates | Apu Coropuna S.R.L.            
RELATED PARTY TRANSACTIONS:            
Ownership percentage 30.00%          
Affiliates | Minimum            
RELATED PARTY TRANSACTIONS:            
Aggregate consideration of Material Affiliate Transaction to be be authorized by the General Counsel and CFO $ 8.0          
Affiliates | Maximum            
RELATED PARTY TRANSACTIONS:            
Aggregate consideration of Material Affiliate Transaction to be be authorized by the General Counsel and CFO 10.0          
Related party receivable and payable 0.1       0.1  
Total sales 0.1 0.1        
Threshold revenue from related parties 0.1 0.1        
Grupo Mexico and affiliates | Affiliates            
RELATED PARTY TRANSACTIONS:            
Total sales 31.4 22.3        
Asarco LLC ("Asarco") | Affiliates            
RELATED PARTY TRANSACTIONS:            
Related parties receivable current: 8.2       7.1  
Other accrued liabilities 13.9       6.0  
Total purchases 7.8 1.2        
Total sales 13.0 6.7        
AMMINCO Apoyo Administrativo, S.A. de C.V. ("AMMINCO") | Affiliates            
RELATED PARTY TRANSACTIONS:            
Other accrued liabilities 8.8       6.0  
Total purchases 2.5 2.5        
Eolica El Retiro, S.A.P.I. de C.V.            
RELATED PARTY TRANSACTIONS:            
Number of wind turbines | item           37
Eolica El Retiro, S.A.P.I. de C.V. | Affiliates            
RELATED PARTY TRANSACTIONS:            
Other accrued liabilities 0.4       0.4  
Total purchases $ 0.4 $ 0.1        
Percentage of supply to third-party energy users 33.30% 3.40%        
Ferrocarril Mexicano, S.A. de C.V. | Affiliates            
RELATED PARTY TRANSACTIONS:            
Other accrued liabilities $ 8.2       2.9  
Total purchases 5.5 $ 8.1        
Grupo Mexico | Affiliates            
RELATED PARTY TRANSACTIONS:            
Total purchases 1.0 1.0        
Donations 0.0 0.6        
Grupo Mexico Servicios | Affiliates            
RELATED PARTY TRANSACTIONS:            
Other accrued liabilities 6.9       4.3  
Total purchases 5.0 5.0        
Mexico Generadora de Energia S. de R.L. ("MGE") | Mexico            
RELATED PARTY TRANSACTIONS:            
Number of natural gas-fired combined cycle power generating units | item       2    
Mexico Generadora de Energia S. de R.L. ("MGE") | Affiliates            
RELATED PARTY TRANSACTIONS:            
Related parties receivable current: 5.4       5.4  
Other accrued liabilities 16.7       15.9  
Total purchases 59.7 61.7        
Total sales $ 18.4 $ 15.6        
Mexico Generadora de Energia S. de R.L. ("MGE") | Affiliates | Mexico            
RELATED PARTY TRANSACTIONS:            
Net total capacity (in megawatts) | MW       516.2    
Percentage of supply to third-party energy users 3.70% 5.20%        
Mexico Compania Constructora S.A de C.V. | Affiliates            
RELATED PARTY TRANSACTIONS:            
Other accrued liabilities $ 4.2       8.0  
Total purchases 14.2 $ 20.6        
Parque Eolico de Fenicias, S. de R.L. de C.V. | Affiliates            
RELATED PARTY TRANSACTIONS:            
Other accrued liabilities 4.4       2.6  
Total purchases $ 8.6          
Purchase agreement, contracted power capacity (in megawatts per year) | MWh     611,400      
Term of power purchase agreement related to sale of power plant     20 years      
Percentage of supply to third-party energy users 74.80%          
Grupo Mexico Servicios de Ingenieria, S.A. de C.V. | Affiliates            
RELATED PARTY TRANSACTIONS:            
Other accrued liabilities $ 0.8       2.1  
Total purchases 2.3 4.0        
Boutique Bowling de Mexico, S.A. de C.V. | Affiliates            
RELATED PARTY TRANSACTIONS:            
Other accrued liabilities 0.6       0.5  
Total purchases 0.1 0.2        
Empresarios Industriales de Mexico, S.A. de C.V | Affiliates            
RELATED PARTY TRANSACTIONS:            
Related parties receivable current: 1.0       0.9  
Total sales 0.1 0.1        
Mexico Transportes Aereos S.A. de C.V. ("Mextransport") | Affiliates            
RELATED PARTY TRANSACTIONS:            
Related parties receivable current: 0.4          
Other accrued liabilities 0.2       0.1  
Total purchases 0.8 0.7        
Total sales 0.7 0.6        
Operadora de Cinemas S.A. de C.V. | Affiliates            
RELATED PARTY TRANSACTIONS:            
Related parties receivable current: 0.1       0.1  
Other accrued liabilities 0.5       $ 0.4  
Total purchases $ 0.1 $ 0.1