v3.26.1
INVESTMENTS - Market value of investees (Details) - BRL (R$)
R$ in Thousands
12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
ISA Energia    
Associates    
Percentage of shares in associates 21.63% 21.63%
Fair value R$ 4,086,824 R$ 3,581,661
ISA Energia | COMMON    
Associates    
Percentage of shares in associates 9.73%  
ISA Energia | PREFERRED    
Associates    
Percentage of shares in associates 29.28%  
Equatorial Maranhão Distribuidora de Energia S.A.    
Associates    
Percentage of shares in associates 33.41%  
Fair value R$ 1,708,332 1,270,047
Equatorial Maranhão Distribuidora de Energia S.A. | COMMON    
Associates    
Percentage of shares in associates 33.34%  
Equatorial Maranhão Distribuidora de Energia S.A. | PREFERRED    
Associates    
Percentage of shares in associates 37.29%  
Empresa Metropolitana de Águas e Energia S.A. - EMAE    
Associates    
Fair value   R$ 627,521