v3.26.1
Note 14 - Investments in non-consolidated companies (Details Textual)
$ / shares in Units, $ in Thousands
 12 Months Ended
Dec. 31, 2025
USD ($)
$ / shares
Dec. 31, 2024
USD ($)
Dec. 31, 2023
USD ($)
Dec. 31, 2025
R$ / shares
Feb. 13, 2019
USD ($)
Disclosure of unconsolidated structured entities [line items]          
Total investments in subsidiaries, joint ventures and associates $ 1,561,212 $ 1,543,657 $ 1,608,804    
Gain (loss) recognised as result of remeasuring to fair value equity interest in acquiree held by acquirer before business combination      
Bargain purchase gain 2,212 $ 3,162    
Dividends and distributions declared $ 62,022 71,212      
Proportion of ownership interest in subsidiary 50.00%        
Techgen S.A. [member]          
Disclosure of unconsolidated structured entities [line items]          
Total investments in subsidiaries, joint ventures and associates $ 73,900        
Ternium and Usiminas [member]          
Disclosure of unconsolidated structured entities [line items]          
Dividends and distributions declared $ 62,000 $ 73,800      
Usiminas [member]          
Disclosure of unconsolidated structured entities [line items]          
Proportion of voting rights held in associate 6.76% 6.76%      
Fair value of investments in associates for which there are quoted market prices $ 52,900        
Total investments in subsidiaries, joint ventures and associates 108,600        
Loss Recognised Due to Particiaption Increase in Nonconsolidated Companies $ 25,500        
Proportion of ownership interest in subsidiary 3.96%        
Usiminas [member] | Ordinary shares [member]          
Disclosure of unconsolidated structured entities [line items]          
Closing price, per share (in BRL per share) | (per share) $ 1.08     R$ 5.96  
Usiminas [member] | Preference shares [member]          
Disclosure of unconsolidated structured entities [line items]          
Closing price, per share (in BRL per share) | (per share) $ 1.08     R$ 5.95  
Ternium S.A. [member]          
Disclosure of unconsolidated structured entities [line items]          
Proportion of voting rights held in associate 11.70% 11.70%      
Closing price, per ads (in dollars per share) | $ / shares $ 38.19        
Fair value of investments in associates for which there are quoted market prices $ 877,300        
Total investments in subsidiaries, joint ventures and associates $ 1,375,100        
Techgen S.A. [member]          
Disclosure of unconsolidated structured entities [line items]          
Proportion of ownership interest in associate 22.00%        
Exposure to transportation capacity agreements $ 33,100        
Exposure to the purchase of clean energy certificates 16,100        
Techgen S.A. [member] | Tenaris [member]          
Disclosure of unconsolidated structured entities [line items]          
Loans and receivables $ 68,800        
Proportion of corporate guarantee covering obligations 22.00%        
Techgen S.A. [member] | Several banks, to refinance obligations [member]          
Disclosure of unconsolidated structured entities [line items]          
Debt instruments issued         $ 640,000
Techgen S.A. [member] | Tecpetrol International S.A. [member]          
Disclosure of unconsolidated structured entities [line items]          
Proportion of ownership interest in associate 30.00%        
Techgen S.A. [member] | Tenaris SA [member]          
Disclosure of unconsolidated structured entities [line items]          
Debt service coverage ratio, covered, percent 22.00%        
Letters of credit, covered $ 9,700        
Techgen S.A. [member] | Ternium S.A. [member]          
Disclosure of unconsolidated structured entities [line items]          
Proportion of ownership interest in associate 48.00%        
Techgen S.A. [member] | Ternium S.A. [member] | Tecpetrol International S.A. [member] | Tenaris [member]          
Disclosure of unconsolidated structured entities [line items]          
Loans and receivables $ 312,700