DERIVATIVE FINANCIAL INSTRUMENTS (Narrative) (Details) - Dec. 31, 2025 € in Millions, $ in Millions	EUR (€)	USD ($)
Forward contract \| Ternium Mexico S.A. de C.V.
Disclosure of detailed information about financial instruments [line items]
Notional amount \| €	€ 208.9
Forward contract \| Ternium Mexico S.A. de C.V. \| EUR
Disclosure of detailed information about financial instruments [line items]
Notional amount		$ 242.7
Forward contract \| Mineraçao Usiminas \| Iron Ore
Disclosure of detailed information about financial instruments [line items]
Notional amount		26.9
Swap contract \| Ternium Mexico S.A. de C.V. \| Zinc
Disclosure of detailed information about financial instruments [line items]
Notional amount		2.8
Non-deliverable forward contract \| Ternium Mexico S.A. de C.V. \| MXN
Disclosure of detailed information about financial instruments [line items]
Notional amount		344.5
Non-deliverable forward contract \| Ternium Guatemala \| GTQ
Disclosure of detailed information about financial instruments [line items]
Notional amount		2.0
Non-deliverable forward contract \| Ternium Brasil Ltda. \| EUR
Disclosure of detailed information about financial instruments [line items]
Notional amount		$ 10.0