v3.26.1
Other assets and liabilities - Additional information (Details) - EUR (€)
€ in Millions
 1 Months Ended 12 Months Ended
Mar. 31, 2025
Mar. 31, 2024
Dec. 31, 2025
Dec. 31, 2024
Disclosure Of Detailed Information About Other Assets And Liabilities [Line Items]        
Value added tax receivables     € 763 € 847
Current value added tax receivables     746 711
Current tax credits related to renovation of residential buildings and energy saving     1,412 1,210
Non-current tax credits related to renovation of residential buildings and energy saving     1,570 2,298
Reimbursement receivable for past environmental expenses, net of discounting factor     550 732
Gas volume prepayments, current     2 3
Gas volume prepayments, non-current     85 295
Non-current receivables for investing activities     169 144
Prepaid electronic fuel vouchers     346 331
Advances received from customers for future gas supplies     227 65
Excise duties and consumer taxes     811 895
Current value added tax payables     384 405
Value of gas not withdrawn by customers due to triggering of take-or-pay clause     57 303
Payables related to investing activities     49 96
Non-current payables to factoring companies connected with the tax credit transfer     1,422 2,104
Change in non‐controlling interest     5,072 588
Engie SA        
Disclosure Of Detailed Information About Other Assets And Liabilities [Line Items]        
Advances received     44 218
Current advances received     12 55
Eni Plenitude SpA SB | Energy Infrastructure Partners (EIP)        
Disclosure Of Detailed Information About Other Assets And Liabilities [Line Items]        
Change in non‐controlling interest € 209 € 588    
Book value of put option     541 392
Societa Oleodotti Meridionali SpA        
Disclosure Of Detailed Information About Other Assets And Liabilities [Line Items]        
Advances received     496 486
Exploration & Production        
Disclosure Of Detailed Information About Other Assets And Liabilities [Line Items]        
Underlifting positions     199 318
Current overlifting imbalances     € 267 € 396