v3.26.1
Operating costs and expenses (Details) - BRL (R$)
R$ in Thousands
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
IfrsStatementLineItems [Line Items]      
Cost of sales R$ (23,991,688) R$ (16,603,073) R$ (16,051,866)
Selling expense (743,276) (917,589) (984,060)
Amount recorded as expense (Note 31) (62,067) (557,789) (652,920)
Administrative expenses (1,018,282) (2,311,438) (1,597,548)
[custom:SellingGeneralAndAdministrativeExpenses] (25,815,313) (20,389,889) (19,286,394)
Expenses, by nature (25,815,313) (20,389,889) (19,286,394)
Salaries Payroll Charges And Benefits [Member]      
IfrsStatementLineItems [Line Items]      
Cost of sales (2,108,947) (2,357,526) (2,717,005)
Selling expense (260,098) (335,382) (347,536)
Administrative expenses (333,274) (602,217) (423,948)
Expenses, by nature (2,702,319) (3,295,125) (3,488,489)
Pension Obligations [Member]      
IfrsStatementLineItems [Line Items]      
Cost of sales (49,920) (23,704) (36,998)
Selling expense (7,017) (3,825) (3,359)
Administrative expenses (135,423) (78,428) (122,248)
Expenses, by nature (192,360) (105,957) (162,605)
Construction Costs [Member]      
IfrsStatementLineItems [Line Items]      
Cost of sales (14,437,363) (6,085,895) (5,474,729)
Expenses, by nature (14,437,363) (6,085,895) (5,474,729)
General Supplies [Member]      
IfrsStatementLineItems [Line Items]      
Cost of sales (363,122) (345,771) (356,481)
Selling expense (18,599) (4,679) (6,746)
Administrative expenses (6,080) (108,901) (23,008)
Expenses, by nature (387,801) (459,351) (386,235)
Treatment Supplies [Member]      
IfrsStatementLineItems [Line Items]      
Cost of sales (503,771) (577,639) (558,557)
Expenses, by nature (503,771) (577,639) (558,557)
Outside Services [Member]      
IfrsStatementLineItems [Line Items]      
Cost of sales (2,141,555) (1,915,851) (1,843,213)
Selling expense (397,062) (423,964) (439,995)
Administrative expenses (287,318) (391,637) (287,744)
Expenses, by nature (2,825,935) (2,731,452) (2,570,952)
Electricity One [Member]      
IfrsStatementLineItems [Line Items]      
Cost of sales (1,532,772) (1,573,067) (1,514,542)
Selling expense (1,650) (658) (673)
Administrative expenses (125) (1,297) (2,020)
Expenses, by nature (1,534,547) (1,575,022) (1,517,235)
General Expenses [Member]      
IfrsStatementLineItems [Line Items]      
Cost of sales (790,184) (1,246,474) (967,148)
Selling expense (2,334) (98,800) (116,933)
Administrative expenses (75,429) (898,587) (509,984)
Expenses, by nature (867,937) (2,243,861) (1,594,065)
Depreciation And Amortization [Member]      
IfrsStatementLineItems [Line Items]      
Cost of sales (2,064,054) (2,477,146) (2,583,193)
Selling expense (56,516) (50,281) (68,818)
Administrative expenses (88,192) (149,215) (138,575)
Expenses, by nature (2,208,762) (2,676,642) (2,790,586)
Allowance For Doubtful Accounts [Member]      
IfrsStatementLineItems [Line Items]      
Amount recorded as expense (Note 31) (62,067) (557,789) (652,920)
Expenses, by nature (62,067) (557,789) (652,920)
Tax Expense [Member]      
IfrsStatementLineItems [Line Items]      
Administrative expenses (92,441) (81,156) (90,021)
Expenses, by nature R$ (92,441) R$ (81,156) R$ (90,021)