Capital and funding - Disclosure of Fair Value Reserve (Details) - EUR (€) € in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
|
| Equity and liabilities [abstract] | ||
| Fair value reserve at beginning of period | € 600 | € 392 |
| Gains/(losses) on equity instruments | (14) | 60 |
| Gains/(losses) on cash flow hedges | (196) | 210 |
| Hedging (gains)/losses transferred to non-financial assets | (58) | (62) |
| Fair value reserve at end of period | € 332 | € 600 |