| (in thousands of euros) | Note | December 31, 2024 | December 31, 2023 | 
|---|---|---|---|
| ASSETS | ASSETS Note 
 | ASSETSDecember 31, 2024 
 | ASSETSDecember 31, 2023 
 | 
| Intangible assets | Intangible assets Note9.1 | Intangible assetsDecember 31, 20241,914 | Intangible assetsDecember 31, 20231,954 | 
| Concessions and business goodwill | Concessions and business goodwill Note 
 | Concessions and business goodwillDecember 31, 2024 2,991 | Concessions and business goodwillDecember 31, 2023 2,991 | 
| Other intangible assets | Other intangible assets Note 
 | Other intangible assetsDecember 31, 2024 507 | Other intangible assetsDecember 31, 2023 507 | 
| Amortization & depreciation (intangible assets) | Amortization & depreciation (intangible assets) Note 
 | Amortization & depreciation (intangible assets)December 31, 2024 (1,584) | Amortization & depreciation (intangible assets)December 31, 2023 (1,544) | 
| Property, plant and equipment | Property, plant and equipment Note9.2 | Property, plant and equipment December 31, 20247,012 | Property, plant and equipment December 31, 20237,405 | 
| Land | Land Note 
 | LandDecember 31, 2024 2,291 | LandDecember 31, 2023 2,291 | 
| Buildings | Buildings Note 
 | BuildingsDecember 31, 2024 3,044 | BuildingsDecember 31, 2023 3,044 | 
| Machinery and equipment | Machinery and equipment Note 
 | Machinery and equipmentDecember 31, 2024 1,133 | Machinery and equipmentDecember 31, 2023 1,133 | 
| Other (property, plant and equipment) | Other (property, plant and equipment) Note 
 | Other (property, plant and equipment)December 31, 2024 39,838 | Other (property, plant and equipment)December 31, 2023 39,227 | 
| Amortization & depreciation of property, plant and equipment | Amortization & depreciation of property, plant and equipment Note 
 | Amortization & depreciation of property, plant and equipmentDecember 31, 2024 (39,294) | Amortization & depreciation of property, plant and equipmentDecember 31, 2023 (38,290) | 
| Investments and other financial assets | Investments and other financial assets Note 
 | Investments and other financial assetsDecember 31, 20245,617,743 | Investments and other financial assetsDecember 31, 20235,601,596 | 
| Long-term equity investments | Long-term equity investments Note9.3 | Long-term equity investmentsDecember 31, 2024 5,723,479 | Long-term equity investmentsDecember 31, 2023 5,723,479 | 
| Impairment on equity investments | Impairment on equity investments Note9.3 | Impairment on equity investmentsDecember 31, 2024 (123,115) | Impairment on equity investmentsDecember 31, 2023 (123,115) | 
| Loans and receivables related to equity investments | Loans and receivables related to equity investments Note9.4 | Loans and receivables related to equity investmentsDecember 31, 2024 17,204 | Loans and receivables related to equity investmentsDecember 31, 2023 1,057 | 
| Loans and other financial assets | Loans and other financial assets Note 
 | Loans and other financial assetsDecember 31, 2024 277 | Loans and other financial assetsDecember 31, 2023 277 | 
| Impairment on other financial assets | Impairment on other financial assets Note 
 | Impairment on other financial assetsDecember 31, 2024 (102) | Impairment on other financial assetsDecember 31, 2023 (102) | 
| Non-current assets | Non-current assets Note 
 | Non-current assetsDecember 31, 20245,626,669 | Non-current assetsDecember 31, 20235,610,955 | 
| Trade receivables | Trade receivables Note 
 | Trade receivablesDecember 31, 2024 9,499 | Trade receivablesDecember 31, 2023 1,072 | 
| Other receivables | Other receivables Note 
 | Other receivablesDecember 31, 2024 14,071 | Other receivablesDecember 31, 2023 15,436 | 
| Marketable securities | Marketable securities Note10 | Marketable securitiesDecember 31, 2024 314,286 | Marketable securitiesDecember 31, 2023 280,159 | 
| Cash and cash equivalents | Cash and cash equivalents Note 
 | Cash and cash equivalentsDecember 31, 2024 54 | Cash and cash equivalentsDecember 31, 2023 120,958 | 
| Current assets | Current assets Note 
 | Current assetsDecember 31, 2024337,910 | Current assetsDecember 31, 2023417,625 | 
| Prepaid expenses | Prepaid expenses Note 
 | Prepaid expensesDecember 31, 2024 412 | Prepaid expensesDecember 31, 2023 410 | 
| Deferred expenses | Deferred expenses Note11 | Deferred expensesDecember 31, 2024 4,274 | Deferred expensesDecember 31, 2023 603 | 
| Bond redemption premiums | Bond redemption premiums Note12 | Bond redemption premiumsDecember 31, 2024 – | Bond redemption premiumsDecember 31, 2023 429 | 
| Unrealized currency translation losses | Unrealized currency translation losses Note 
 | Unrealized currency translation lossesDecember 31, 2024 – | Unrealized currency translation lossesDecember 31, 2023 – | 
| Total assets | Total assets Note 
 | Total assetsDecember 31, 2024 5,969,265 | Total assetsDecember 31, 2023 6,030,022 |