v3.26.1
Consolidated shareholders' equity - Additional Information (Details) - EUR (€)
 6 Months Ended
Apr. 29, 2026
Apr. 30, 2025
Feb. 02, 2025
Jun. 30, 2026
Jun. 30, 2025
Jun. 29, 2026
Jan. 28, 2026
Jan. 29, 2025
Disclosure of classes of share capital [Line Items]                
Share capital       € 2,428,198,054        
Number of shares (in shares)       1,214,099,027        
Par value per share (in euros per share)       € 2        
Payments to acquire or redeem entity's shares       € 1,009,000,000 € 4,003,000,000      
Cancellation of treasury shares       € 596,000,000        
Share Repurchase 2025 Program                
Disclosure of classes of share capital [Line Items]                
Period of share repurchase program   18 months            
Number of shares repurchased (in shares)       12,571,455        
Payments to acquire or redeem entity's shares       € 1,003,000,000        
Share repurchase program, authorized, amount               € 5,000,000,000
Share Repurchase 2025 Program | L'Oréal                
Disclosure of classes of share capital [Line Items]                
Number of shares repurchased (in shares)     29,556,650          
Percentage of Sanofi's share capital acquired     2.34%          
Share repurchase program, amount paid     € 3,000,000,000          
Per share value of shares repurchased (in euros per share)     € 101.50          
Share Repurchase 2026 Program                
Disclosure of classes of share capital [Line Items]                
Period of share repurchase program 18 months              
Employees share ownership plan                
Disclosure of classes of share capital [Line Items]                
Subscription price (in euros per share)             € 59.87 € 72.97
Number of shares subscribed (in shares)         2,260,776 2,431,494    
Number of shares issued immediately for employer's contribution (in shares)         116,794 104,327    
Expense recognized       € 46,000,000 € 31,000,000      
Sanofi                
Disclosure of classes of share capital [Line Items]                
Number of restricted shares vested (in shares)       3,072,520        
Number of restricted shares alloted in regards of capital increase (in shares)       1,185,997        
Sanofi | Share capital                
Disclosure of classes of share capital [Line Items]                
Capital increase by exercise of stock subscription options (in shares)       30,070        
Capital increase by issuance of restricted shares (in shares)       1,886,523