v3.26.1
Investment in associates and joint ventures - Additional information (Details) - EUR (€)
€ in Millions
6 Months Ended 12 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Disclosure of investments in associates and joint ventures [line items]      
Gross proceeds € 458 € 116  
TMBThanachart Bank Public Company Limited      
Disclosure of investments in associates and joint ventures [line items]      
Percentage of ownership interest 19.50%    
Share of results € 69   € 136
Gross proceeds 304    
Accumulated impairment losses € 395   € 395
Total for all associates | TMBThanachart Bank Public Company Limited      
Disclosure of investments in associates and joint ventures [line items]      
Percentage of ownership interest 20.00%   23.00%
Associates and joint ventures      
Disclosure of investments in associates and joint ventures [line items]      
Share of results € 127   € 209