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 |