v3.26.1
Provisions for employee benefits - Costs charged to the profit and loss account (Details) - EUR (€)
€ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Disclosure Of Benefit Plans [Line Items]    
Current service cost € 66 € 71
Past service cost and (gains) losses on settlements (3) 12
- interest cost on liabilities 33 38
- interest income on plan assets (18) (14)
Interest cost (income), net 15 24
Remeasurements for long-term plans (8) 1
Administrative fees paid 1 1
Total 71 109
Payroll and related costs    
Disclosure Of Benefit Plans [Line Items]    
Interest cost (income), net 8 11
Total 64 96
Financial income (expense)    
Disclosure Of Benefit Plans [Line Items]    
Interest cost (income), net 7 13
Total 7 13
Other benefit plans    
Disclosure Of Benefit Plans [Line Items]    
Current service cost 57 56
Past service cost and (gains) losses on settlements (9) 3
- interest cost on liabilities 8 11
Interest cost (income), net 8 11
Remeasurements for long-term plans (8) 1
Total 48 71
Other benefit plans | Payroll and related costs    
Disclosure Of Benefit Plans [Line Items]    
Interest cost (income), net 8 11
Total 48 71
Defined benefit plan    
Disclosure Of Benefit Plans [Line Items]    
Current service cost 9 15
Past service cost and (gains) losses on settlements 6 9
- interest cost on liabilities 25 27
- interest income on plan assets (18) (14)
Interest cost (income), net 7 13
Administrative fees paid 1 1
Total 23 38
Defined benefit plan | Payroll and related costs    
Disclosure Of Benefit Plans [Line Items]    
Total 16 25
Defined benefit plan | Financial income (expense)    
Disclosure Of Benefit Plans [Line Items]    
Interest cost (income), net 7 13
Total 7 13
Italian defined benefit plans    
Disclosure Of Benefit Plans [Line Items]    
Current service cost 1 1
- interest cost on liabilities 5 5
Interest cost (income), net 5 5
Total 6 6
Italian defined benefit plans | Payroll and related costs    
Disclosure Of Benefit Plans [Line Items]    
Total 1 1
Italian defined benefit plans | Financial income (expense)    
Disclosure Of Benefit Plans [Line Items]    
Interest cost (income), net 5 5
Total 5 5
Foreign defined benefit plan    
Disclosure Of Benefit Plans [Line Items]    
Current service cost 6 12
Past service cost and (gains) losses on settlements 1 9
- interest cost on liabilities 17 18
- interest income on plan assets (18) (14)
Interest cost (income), net (1) 4
Administrative fees paid 1 1
Total 7 26
Foreign defined benefit plan | Payroll and related costs    
Disclosure Of Benefit Plans [Line Items]    
Total 8 22
Foreign defined benefit plan | Financial income (expense)    
Disclosure Of Benefit Plans [Line Items]    
Interest cost (income), net (1) 4
Total (1) 4
FISDE and other foreign medical plans    
Disclosure Of Benefit Plans [Line Items]    
Current service cost 2 2
Past service cost and (gains) losses on settlements 5  
- interest cost on liabilities 3 4
Interest cost (income), net 3 4
Total 10 6
FISDE and other foreign medical plans | Payroll and related costs    
Disclosure Of Benefit Plans [Line Items]    
Total 7 2
FISDE and other foreign medical plans | Financial income (expense)    
Disclosure Of Benefit Plans [Line Items]    
Interest cost (income), net 3 4
Total € 3 € 4