v3.26.1
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT - Derivative financial instruments for debt protection (Details) - BRL (R$)
12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Asset R$ 666,399,000 R$ (1,058,820,000) R$ 283,908,000
Liability 728,646,000 (974,381,000)  
Derivative financial liabilities held for hedging 22,863,888,000 23,257,512,000 R$ 6,757,343,000
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (3,335,118,000) (1,566,482,000)  
Debt Protection Derivative      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Asset 1,074,473,000 2,152,316,000  
Liability 1,803,119,000 1,177,935,000  
Credit agreement - US$ vs CDI, January 8,2025      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 493,000,000    
Asset 0 118,733,000  
Liability 0 0  
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (11,948,000) 109,356,000  
Bonds - US$ vs CDI, February 4,2025      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 2,535,300,000    
Asset 0 500,998,000  
Liability 0 0  
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (193,974,000) 560,392,000  
Credit agreement - US$ vs CDI, August 29,2025      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 219,150,000    
Asset 0 54,290,000  
Liability 0 0  
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (44,993,000) 52,930,000  
Credit agreement - US$ vs CDI, December 9,2025      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 500,000,000    
Asset 0 13,170,000  
Liability 0 0  
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (103,798,000) 13,170,000  
Credit agreement - EUR vs CDI, December 23,2025      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 500,000,000    
Asset 0 5,245,000  
Liability 0 0  
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (38,697,000) 5,245,000  
Credit agreement - US$ vs CDI, February 27,2026      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 500,000,000    
Asset 0 0  
Liability 42,071,000 0  
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (63,887,000) 0  
Credit agreement - US$ vs CDI, August 11,2026      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 350,000,000    
Asset 0 0  
Liability 11,840,000 0  
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (11,840,000) 0  
Credit agreement - US$ vs CDI, December 4,2026      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 322,560,000    
Asset 1,895,000 0  
Liability 0 0  
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness 1,895,000 0  
Credit agreement - EUR vs CDI, December 21,2026      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 245,000,000    
Asset 1,764,000 0  
Liability 0 0  
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness 1,764,000 0  
Credit agreement - EUR vs CDI, August 16,2027      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 400,000,000    
Asset 25,446,000 0  
Liability 42,633,000 0  
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (17,186,000) 0  
Credit agreement - US$ vs CDI, December 3,2027      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 215,040,000    
Asset 18,181,000 0  
Liability 17,981,000 0  
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness 200,000 0  
Credit agreement - US$ vs CDI, December 16,2027      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 216,760,000    
Asset 17,387,000 0  
Liability 17,758,000 0  
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (371,000) 0  
Credit agreement - US$ vs CDI, June 20,2029      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 232,873,000    
Asset 16,712,000 47,415,000  
Liability 1,752,000 7,603,000  
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (33,446,000) 41,141,000  
Bonds - US$ vs CDI, February 4,2030      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 3,810,300,000    
Asset 428,933,000 715,544,000  
Liability 355,301,000 235,194,000  
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (700,988,000) 634,410,000  
Debentures - IPCA vs CDI, June 15,2031      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 4,900,000,000    
Asset 331,658,000 142,788,000  
Liability 279,429,000 343,924,000  
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (88,822,000) (296,800,000)  
Debentures - IPCA vs CDI, September 15,2034      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 1,630,000,000    
Asset 87,849,000 0  
Liability 103,383,000 89,867,000  
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (14,779,000) (89,867,000)  
SACE - US$ vs CDI, December 4,2034      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 2,378,400,000    
Asset 0 266,397,000  
Liability 207,039,000 185,005,000  
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (500,256,000) 81,392,000  
Bonds - US$ vs CDI, January 11,2035      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 4,229,025,000    
Asset 0 287,736,000  
Liability 586,756,000 316,342,000  
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (851,612,000) (28,606,000)  
Debentures - IPCA vs CDI, July 16,2035      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 2,000,000,000    
Asset 96,620,000 0  
Liability 102,499,000 0  
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (5,879,000) 0  
Debentures - IPCA vs CDI, September 17,2035      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 700,000,000    
Asset 48,028,000 0  
Liability 34,677,000 0  
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness 13,351,000 0  
Long-Term Commitment Derivatives      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Asset 62,247,000 84,439,000  
Liability 0 0  
NDF US$, April 30,2025      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 67,113,000    
Asset 0 224,000  
Liability 0 0  
NDF US$ and Primary Aluminum, October 1,2025      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 444,000    
Asset 0 91,000  
Liability 0 0  
NDF US$ and Primary Aluminum, November 1,2025      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 447,000    
Asset 0 92,000  
Liability 0 0  
NDF US$ and Primary Aluminum, December 1,2025      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 451,000    
Asset 0 91,000  
Liability 0 0  
NDF US$ and Primary Aluminum, February 1,2026      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 33,089,000    
Asset 4,695,000 6,548,000  
Liability 0 0  
NDF US$, February 27,2026      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 1,636,000    
Asset 251,000 0  
Liability 0 0  
NDF US$ and Primary Aluminum, March 1,2026      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 58,884,000    
Asset 8,312,000 11,635,000  
Liability 0 0  
NDF US$ and Primary Aluminum, April 1,2026      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 59,296,000    
Asset 8,191,000 11,684,000  
Liability 0 0  
NDF US$ and Primary Aluminum, May 1,2026      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 59,718,000    
Asset 8,316,000 11,752,000  
Liability 0 0  
NDF US$ and Primary Aluminum, June 1,2026      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 60,181,000    
Asset 8,313,000 11,726,000  
Liability 0 0  
NDF US$, June 30,2026      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 650,000    
Asset 103,000 0  
Liability 0 0  
NDF US$ and Primary Aluminum, July 1,2026      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 60,617,000    
Asset 8,338,000 11,751,000  
Liability 0 0  
NDF US$, July 31,2026      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 650,000    
Asset 103,000 0  
Liability 0 0  
NDF US$ and Primary Aluminum, August 1,2026      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 61,081,000    
Asset 8,354,000 11,852,000  
Liability 0 0  
NDF US$, August 31,2026      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 337,000    
Asset 53,000 0  
Liability 0 0  
NDF US$ and Primary Aluminum, September 1,2026      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 34,560,000    
Asset 5,098,000 6,993,000  
Liability 0 0  
NDF US$, November 30,2026      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 626,000    
Asset 100,000 0  
Liability 0 0  
NDF US$, December 30,2026      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 1,487,000    
Asset 238,000 0  
Liability 0 0  
NDF US$, January 29,2027      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 1,769,000    
Asset 283,000 0  
Liability 0 0  
NDF US$, February 26,2027      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 1,395,000    
Asset 224,000 0  
Liability 0 0  
NDF US$, March 31,2027      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 2,068,000    
Asset 333,000 0  
Liability 0 0  
NDF US$, April 30,2027      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 1,665,000    
Asset 269,000 0  
Liability 0 0  
NDF US$, May 31,2027      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 1,178,000    
Asset 192,000 0  
Liability 0 0  
NDF US$, June 30,2027      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 757,000    
Asset 124,000 0  
Liability 0 0  
NDF US$, July 30,2027      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 252,000    
Asset 42,000 0  
Liability 0 0  
NDF US$, August 31,2027      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 409,000    
Asset 67,000 0  
Liability 0 0  
NDF US$, September 30,2027      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 157,000    
Asset 26,000 0  
Liability 0 0  
NDF US$, October 29,2027      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 241,000    
Asset 40,000 0  
Liability 0 0  
NDF US$, November 30,2027      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 325,000    
Asset 54,000 0  
Liability 0 0  
NDF US$, December 30,2027      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 168,000    
Asset 28,000 0  
Liability 0 0  
NDF US$, January 31,2028      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 337,000    
Asset 57,000 0  
Liability 0 0  
NDF US$, February 25,2028      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 84,000    
Asset 14,000 0  
Liability 0 0  
NDF US$, March 31,2028      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Notional value 168,000    
Asset 29,000 0  
Liability 0 0  
Derivative Result      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (2,665,266,000) 1,151,248,000  
Credit agreement - US$ vs CDI, June 18,2026      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness 0 68,485,000  
Debt Result      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (669,852,000) (2,717,730,000)  
Credit agreement, January 8,2025      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness 10,718,000 (165,382,000)  
Bonds, February 4,2025      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness 122,640,000 (765,876,000)  
Credit agreement, August 29,2025      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness 25,167,000 (68,059,000)  
Credit agreement, December 9,2025      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness 36,360,000 (17,497,000)  
Credit agreement, December 23,2025      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (29,242,000) (7,838,000)  
Credit agreement, February 27,2026      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness 2,664,000 0  
Credit agreement, June 18,2026      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness 0 (257,569,000)  
Credit agreement, August 11,2026      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (9,836,000) 0  
Credit agreement, December 4,2026      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (5,734,000) 0  
Credit agreement, December 21,2026      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (3,181,000) 0  
Credit agreement, August 16,2027      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (10,792,000) 0  
Credit agreement, December 3,2027      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (4,296,000) 0  
Credit agreement, December 16,2027      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (2,789,000) 0  
Credit agreement, June 20,2029      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness 10,681,000 (59,203,000)  
Bonds, February 4,2030      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness 48,287,000 (1,068,243,000)  
Debentures, June 16,2031      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (600,834,000) (53,596,000)  
Debentures, September 15,2034      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (211,489,000) 46,824,000  
SPA (SACE), December 4,2034      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness 130,855,000 (206,217,000)  
Bonds, January 11,2035      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (122,379,000) (95,074,000)  
Debentures, July 16,2035      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (63,802,000) 0  
Debentures, September 17,2035      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness 7,150,000 0  
Designation of protected debt      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness 4,949,360,000 18,630,425,000  
Fair value assessment - result      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness 669,852,000 2,717,730,000  
Amortizations      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness (6,012,836,000) (4,847,986,000)  
Fair value assessment - result      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness 2,665,266,000 (1,151,248,000)  
Fair value assessment - OCI      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness 22,146,000 (84,825,000)  
Amortizations      
FINANCIAL INSTRUMENTS AND RISK MANAGEMENT      
Gain (loss) on change in fair value of hedged item used as basis for recognizing hedge ineffectiveness R$ (962,193,000) R$ (106,655,000)