v3.26.1
Financial instruments and risk management - Fair value settled amounts (Details) - BRL (R$)
R$ in Thousands
 6 Months Ended 9 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Sep. 30, 2025
Disclosure of detailed information about financial instruments [line items]      
Proceeds From (Payments For) Derivative Instrument, Settlement R$ 766,203 R$ 530,655  
Operational Hedge      
Disclosure of detailed information about financial instruments [line items]      
Proceeds From (Payments For) Derivative Instrument, Settlement 531,201 (5,492)  
Commodity Hedge      
Disclosure of detailed information about financial instruments [line items]      
Proceeds From (Payments For) Derivative Instrument, Settlement 194,587 (712)  
Debt hedges      
Disclosure of detailed information about financial instruments [line items]      
Proceeds From (Payments For) Derivative Instrument, Settlement 40,415 536,859  
Zero cost collar (R$ x U.S.$) | Operational Hedge      
Disclosure of detailed information about financial instruments [line items]      
Proceeds From (Payments For) Derivative Instrument, Settlement 455,245 9,922  
NDF (R$ x US$) | Operational Hedge      
Disclosure of detailed information about financial instruments [line items]      
Proceeds From (Payments For) Derivative Instrument, Settlement 75,956 (15,388)  
NDF (RMB x US$) | Operational Hedge      
Disclosure of detailed information about financial instruments [line items]      
Proceeds From (Payments For) Derivative Instrument, Settlement (26)  
Swap VLSFO/other | Commodity Hedge      
Disclosure of detailed information about financial instruments [line items]      
Proceeds From (Payments For) Derivative Instrument, Settlement 194,587 (712)  
Swap CDI x Fixed (US$) | Debt hedges      
Disclosure of detailed information about financial instruments [line items]      
Proceeds From (Payments For) Derivative Instrument, Settlement 333,412 408,373  
Swap IPCA x CDI (notional in Brazilian Reais) | Debt hedges      
Disclosure of detailed information about financial instruments [line items]      
Proceeds From (Payments For) Derivative Instrument, Settlement (242,393) (321,139)  
Swap Pre-Fixed to CDI | Debt hedges      
Disclosure of detailed information about financial instruments [line items]      
Proceeds From (Payments For) Derivative Instrument, Settlement (303,983)  
Swap IPCA to Fixed (US$) | Debt hedges      
Disclosure of detailed information about financial instruments [line items]      
Proceeds From (Payments For) Derivative Instrument, Settlement (16,455)  
Swap SOFR x SOFR (US$) | Debt hedges      
Disclosure of detailed information about financial instruments [line items]      
Proceeds From (Payments For) Derivative Instrument, Settlement   R$ 1,504
Swap SOFR x Fixed (US$) | Debt hedges      
Disclosure of detailed information about financial instruments [line items]      
Proceeds From (Payments For) Derivative Instrument, Settlement 207,410 212,326  
Swap SOFR x Fixed (US$) | Debt hedges      
Disclosure of detailed information about financial instruments [line items]      
Proceeds From (Payments For) Derivative Instrument, Settlement R$ 45,969 R$ 252,250