Marketable debt securities - Narrative (Details) - EUR (€) € in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
|
| Guarantees | |||
| Liabilities secured by mortgage-backed bonds | € 22,624 | ||
| Banco Santander, S.A. | |||
| Guarantees | |||
| Mortgage-backed Bonds, outstanding face value | € 22,360 | ||
| Marketable debt securities | |||
| Guarantees | |||
| Other asset - backed securities personal loans average maturities | 5 years | ||
| Other asset - backed securities SME's average maturities | 7 years | ||
| Liabilities secured by mortgage-backed bonds | € 22,624 | € 22,631 | € 24,619 |
| Marketable debt securities | Minimum | |||
| Guarantees | |||
| Mortgage-backed securities average maturities | 10 years | ||
| Mortgage-backed bonds average maturities | 10 years | ||
| Marketable debt securities | Maximum | |||
| Guarantees | |||
| Mortgage-backed securities loan-to-value ratio (as a percent) | 80.00% | ||
| Mortgage-backed bonds loan-to-value ratio for home loans (as a percent) | 80.00% | ||
| Mortgage-backed bonds loan-to-value ratio for other assets loans (as a percent) | 60.00% |