v3.26.1
Investment in associates and joint ventures - Summary of investments in associates and joint ventures (Details) - EUR (€)
€ in Millions
6 Months Ended 12 Months Ended
Jun. 30, 2026
Dec. 31, 2025
Disclosure of investments in associates and joint ventures [line items]    
Balance sheet value € 1,184 € 1,607
TMBThanachart Bank Public Company Limited    
Disclosure of investments in associates and joint ventures [line items]    
Interest held, percentage 19.50%  
Total for all associates | TMBThanachart Bank Public Company Limited    
Disclosure of investments in associates and joint ventures [line items]    
Interest held, percentage 20.00% 23.00%
Fair value of listed investments € 1,107 € 1,212
Balance sheet value 983 1,307
Other investments in associates and joint ventures    
Disclosure of investments in associates and joint ventures [line items]    
Balance sheet value € 201 € 300