v3.26.1
Investments accounted for using the equity method - Summary of Investments in Associates and Joint Ventures (Details) - EUR (€)
€ / shares in Units, € in Millions
6 Months Ended 12 Months Ended
Jun. 30, 2026
Dec. 31, 2025
Disclosure of transactions between related parties [line items]    
Investments accounted for using the equity method € 3,207 € 3,259
EUROAPI    
Disclosure of transactions between related parties [line items]    
Stock price (in euro per share) € 1.33 € 2.27
MSP Vaccine Company | MCM Vaccine BV    
Disclosure of transactions between related parties [line items]    
Proportion of ownership interest in subsidiary 100.00%  
Infraserv GmbH & Co. Höchst KG    
Disclosure of transactions between related parties [line items]    
Proportion of ownership interest in joint venture 31.20%  
Investments in joint ventures € 93 € 112
MSP Vaccine Company    
Disclosure of transactions between related parties [line items]    
Proportion of ownership interest in joint venture 50.00%  
Investments in joint ventures € 52 € 59
OPAL JV Co    
Disclosure of transactions between related parties [line items]    
Proportion of ownership interest in associate 48.20% 48.20%
Investments in associates € 2,965 € 2,934
Loans to Associates   € 241
OPAL JV Co | CD&R    
Disclosure of transactions between related parties [line items]    
Proportion of ownership interest in associate   50.00%
OPAL JV Co | BPIFrance    
Disclosure of transactions between related parties [line items]    
Proportion of ownership interest in associate   1.80%
EUROAPI    
Disclosure of transactions between related parties [line items]    
Proportion of ownership interest in associate 29.60%  
Investments in associates € 38 € 64
Other investments    
Disclosure of transactions between related parties [line items]    
Proportion of ownership interest in associate 0.00%  
Investments in associates € 59 € 90