v3.25.2
Investment in associates and joint ventures - Additional information (Details) - EUR (€)
€ in Millions
6 Months Ended 12 Months Ended
Jun. 30, 2025
Dec. 31, 2024
TMBThanachart Bank Public Company Limited    
Disclosure of investments in associates and joint ventures [line items]    
Share of results € 65 € 123
Accumulated impairment losses 395 395
Associates and joint ventures    
Disclosure of investments in associates and joint ventures [line items]    
Share of results € 85 € 205
TMBThanachart Bank Public Company Limited    
Disclosure of investments in associates and joint ventures [line items]    
Discount rate (cost of equity) 10.75%  
Growth rate used to extrapolate cash flow projections 2.19%  
TMBThanachart Bank Public Company Limited | Increase in Cash Flows    
Disclosure of investments in associates and joint ventures [line items]    
Sensitivity analysis, reasonably possible change in risk variable (in percent) 0.10  
Increase (decrease) in value in use € 65  
TMBThanachart Bank Public Company Limited | Decrease in Cash Flows    
Disclosure of investments in associates and joint ventures [line items]    
Sensitivity analysis, reasonably possible change in risk variable (in percent) (0.10)  
Increase (decrease) in value in use € (66)  
TMBThanachart Bank Public Company Limited | Increase in Discount Rate    
Disclosure of investments in associates and joint ventures [line items]    
Sensitivity analysis, reasonably possible change in risk variable (in percent) (0.01)  
Increase (decrease) in value in use € 110  
TMBThanachart Bank Public Company Limited | Decrease in Discount Rate    
Disclosure of investments in associates and joint ventures [line items]    
Sensitivity analysis, reasonably possible change in risk variable (in percent) 0.01  
Increase (decrease) in value in use € (87)  
TMBThanachart Bank Public Company Limited | Increase in Terminal Growth Rate    
Disclosure of investments in associates and joint ventures [line items]    
Sensitivity analysis, reasonably possible change in risk variable (in percent) 0.01  
Increase (decrease) in value in use € 75  
TMBThanachart Bank Public Company Limited | Decrease in Terminal Growth Rate    
Disclosure of investments in associates and joint ventures [line items]    
Sensitivity analysis, reasonably possible change in risk variable (in percent) (0.01)  
Increase (decrease) in value in use € (59)  
TMBThanachart Bank Public Company Limited | TMB Public Company Limited    
Disclosure of investments in associates and joint ventures [line items]    
Percentage of ownership interest 23.00% 23.00%