DERIVATIVES AND HEDGING ACTIVITIES - Schedule of Notional Amounts of Outstanding Derivative Positions (Details) - Derivatives designated as hedging instruments € in Millions, ton in Millions, MWh in Millions |
Sep. 30, 2026
EUR (€)
MWh
ton
|
Dec. 31, 2025
EUR (€)
MWh
ton
|
|---|---|---|
| Electricity contracts (MWh) | Cash Flow Hedging | ||
| Derivative [Line Items] | ||
| Derivative, nonmonetary notional amount | 1.7 | 1.9 |
| Natural gas contracts (MWh) | Cash Flow Hedging | ||
| Derivative [Line Items] | ||
| Derivative, nonmonetary notional amount | 8.8 | 12.1 |
| Carbon credit contracts (tons) | Cash Flow Hedging | ||
| Derivative [Line Items] | ||
| Derivative, nonmonetary notional amount | ton | 0.2 | 0.1 |
| External debt | Net Investment Hedging | ||
| Derivative [Line Items] | ||
| Derivative, notional amount | € | € 2,730 | € 3,293 |