v3.26.1
Property, plant and equipment (Details) - BRL (R$)
R$ in Thousands
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
IfrsStatementLineItems [Line Items]    
Balance beginning R$ 22,815,328  
Balance end 23,171,451 R$ 22,815,328
Switching Transmission Equipment [Member]    
IfrsStatementLineItems [Line Items]    
Balance beginning 10,234,615 9,860,267
Additions / depreciation (2,766,864) (2,639,864)
Write-offs (4,185) (6,022)
Transfers 2,384,096 3,020,234
Balance end 9,847,662 10,234,615
Fiber Optic Cables [Member]    
IfrsStatementLineItems [Line Items]    
Balance beginning 86,840 141,784
Additions / depreciation (26,317) (60,165)
Write-offs
Transfers 6,754 5,221
Balance end 67,277 86,840
Free Leased Handsets [Member]    
IfrsStatementLineItems [Line Items]    
Balance beginning 299,456 321,740
Additions / depreciation (221,713) (205,556)
Write-offs (7,744) (4,605)
Transfers 202,756 187,877
Balance end 272,755 299,456
Network infrastructure [member]    
IfrsStatementLineItems [Line Items]    
Balance beginning 2,265,686 2,411,738
Additions / depreciation (358,057) (350,734)
Write-offs (1,333) (1,653)
Transfers 323,614 206,335
Balance end 2,229,910 2,265,686
Informatics Assets [Member]    
IfrsStatementLineItems [Line Items]    
Balance beginning 58,252 87,964
Additions / depreciation (25,537) (36,981)
Write-offs (10) (108)
Transfers 9,075 7,377
Balance end 41,780 58,252
General Use Assets [Member]    
IfrsStatementLineItems [Line Items]    
Balance beginning 243,749 248,773
Additions / depreciation (51,091) (49,736)
Write-offs (350) (709)
Transfers 53,700 45,421
Balance end 246,008 243,749
Right Of Use In Leases [Member]    
IfrsStatementLineItems [Line Items]    
Balance beginning 8,948,060 8,658,612
Additions / depreciation 1,022,193 741,114
Write-offs (146,461) (451,666)
Transfers
Balance end 9,823,792 8,948,060
Land [member]    
IfrsStatementLineItems [Line Items]    
Balance beginning 38,084 38,588
Additions / depreciation
Write-offs (98) (504)
Transfers
Balance end 37,986 38,084
Construction in progress [member]    
IfrsStatementLineItems [Line Items]    
Balance beginning 640,586 642,349
Additions / depreciation 2,944,789 3,470,833
Write-offs (1,099) (131)
Transfers (2,979,995) (3,472,465)
Balance end 604,281 640,586
Gross carrying amount [member]    
IfrsStatementLineItems [Line Items]    
Balance beginning 75,732,043 70,343,331
Additions / depreciation 5,655,358 5,978,275
Write-offs (321,965) (589,563)
Transfers
Balance end 81,065,436 75,732,043
Gross carrying amount [member] | Switching Transmission Equipment [Member]    
IfrsStatementLineItems [Line Items]    
Balance beginning 41,197,166 38,274,244
Additions / depreciation
Write-offs (105,762) (97,312)
Transfers 2,384,096 3,020,234
Balance end 43,475,500 41,197,166
Gross carrying amount [member] | Fiber Optic Cables [Member]    
IfrsStatementLineItems [Line Items]    
Balance beginning 791,983 786,762
Additions / depreciation
Write-offs
Transfers 6,754 5,221
Balance end 798,737 791,983
Gross carrying amount [member] | Free Leased Handsets [Member]    
IfrsStatementLineItems [Line Items]    
Balance beginning 4,256,120 4,082,742
Additions / depreciation 1,230 842
Write-offs (43,654) (15,341)
Transfers 202,756 187,877
Balance end 4,416,452 4,256,120
Gross carrying amount [member] | Network infrastructure [member]    
IfrsStatementLineItems [Line Items]    
Balance beginning 7,925,713 7,737,385
Additions / depreciation
Write-offs (19,824) (18,007)
Transfers 323,614 206,335
Balance end 8,229,503 7,925,713
Gross carrying amount [member] | Informatics Assets [Member]    
IfrsStatementLineItems [Line Items]    
Balance beginning 1,806,939 1,803,782
Additions / depreciation
Write-offs (3,814) (4,220)
Transfers 9,075 7,377
Balance end 1,812,200 1,806,939
Gross carrying amount [member] | General Use Assets [Member]    
IfrsStatementLineItems [Line Items]    
Balance beginning 1,047,340 1,004,301
Additions / depreciation
Write-offs (1,253) (2,382)
Transfers 53,700 45,421
Balance end 1,099,787 1,047,340
Gross carrying amount [member] | Right Of Use In Leases [Member]    
IfrsStatementLineItems [Line Items]    
Balance beginning 18,028,112 15,973,178
Additions / depreciation 2,709,339 2,506,600
Write-offs (146,461) (451,666)
Transfers
Balance end 20,590,990 18,028,112
Gross carrying amount [member] | Land [member]    
IfrsStatementLineItems [Line Items]    
Balance beginning 38,084 38,588
Additions / depreciation
Write-offs (98) (504)
Transfers
Balance end 37,986 38,084
Gross carrying amount [member] | Construction in progress [member]    
IfrsStatementLineItems [Line Items]    
Balance beginning 640,586 642,349
Additions / depreciation 2,944,789 3,470,833
Write-offs (1,099) (131)
Transfers (2,979,995) (3,472,465)
Balance end 604,281 640,586
Accumulated depreciation and amortisation [member]    
IfrsStatementLineItems [Line Items]    
Balance beginning (52,916,715) (47,931,516)
Additions / depreciation (5,137,955) (5,109,364)
Write-offs 160,685 124,165
Transfers
Balance end (57,893,985) (52,916,715)
Accumulated depreciation and amortisation [member] | Switching Transmission Equipment [Member]    
IfrsStatementLineItems [Line Items]    
Balance beginning (30,962,551) (28,413,977)
Additions / depreciation (2,766,864) (2,639,864)
Write-offs 101,577 91,290
Transfers
Balance end (33,627,838) (30,962,551)
Accumulated depreciation and amortisation [member] | Fiber Optic Cables [Member]    
IfrsStatementLineItems [Line Items]    
Balance beginning (705,143) (644,978)
Additions / depreciation (26,317) (60,165)
Write-offs
Transfers
Balance end (731,460) (705,143)
Accumulated depreciation and amortisation [member] | Free Leased Handsets [Member]    
IfrsStatementLineItems [Line Items]    
Balance beginning (3,956,664) (3,761,002)
Additions / depreciation (222,943) (206,398)
Write-offs 35,910 10,736
Transfers
Balance end (4,143,697) (3,956,664)
Accumulated depreciation and amortisation [member] | Network infrastructure [member]    
IfrsStatementLineItems [Line Items]    
Balance beginning (5,660,027) (5,325,647)
Additions / depreciation (358,057) (350,734)
Write-offs 18,491 16,354
Transfers
Balance end (5,999,593) (5,660,027)
Accumulated depreciation and amortisation [member] | Informatics Assets [Member]    
IfrsStatementLineItems [Line Items]    
Balance beginning (1,748,687) (1,715,818)
Additions / depreciation (25,537) (36,981)
Write-offs 3,804 4,112
Transfers
Balance end (1,770,420) (1,748,687)
Accumulated depreciation and amortisation [member] | General Use Assets [Member]    
IfrsStatementLineItems [Line Items]    
Balance beginning (803,591) (755,528)
Additions / depreciation (51,091) (49,736)
Write-offs 903 1,673
Transfers
Balance end (853,779) (803,591)
Accumulated depreciation and amortisation [member] | Right Of Use In Leases [Member]    
IfrsStatementLineItems [Line Items]    
Balance beginning (9,080,052) (7,314,566)
Additions / depreciation (1,687,146) (1,765,486)
Write-offs
Transfers
Balance end (10,767,198) (9,080,052)
Total Property Plant And Equipment Net [Member]    
IfrsStatementLineItems [Line Items]    
Balance beginning 22,815,328 22,411,815
Additions / depreciation 517,403 868,911
Write-offs (161,280) (465,398)
Transfers
Balance end R$ 23,171,451 R$ 22,815,328