Non-current assets held for sale and liabilities associated with non-current assets held for sale - Narrative (Details) - EUR (€) € in Millions |
6 Months Ended | |||
|---|---|---|---|---|
Jan. 09, 2026 |
Jun. 30, 2026 |
Jun. 30, 2025 |
Dec. 31, 2025 |
|
| Agreement for the sale of Santander Bank Polska S.A. | Santander Bank Polska SA | ||||
| Assets And Liabilities Classified As Held For Sale [Line Items] | ||||
| Sale of proportion of ownership interest in subsidiary | 49.00% | |||
| Agreement for the sale of Santander Bank Polska S.A. | Santander Towarzystwo Funduszy Inwestycyjnych S.A. | ||||
| Assets And Liabilities Classified As Held For Sale [Line Items] | ||||
| Sale of proportion of ownership interest in subsidiary | 50.00% | |||
| Assets and liabilities classified as held for sale | ||||
| Assets And Liabilities Classified As Held For Sale [Line Items] | ||||
| Provision recognised for non-current assets held for sale | € 2,241 | € 2,357 | ||
| Net charges recorded against valuation allowances | 30 | € 54 | ||
| Recoveries | € 12 | € 7 | ||