Basis of preparation and significant changes in the current reporting period - Additional information (Details) - EUR (€) € in Millions |
6 Months Ended | 12 Months Ended | |
|---|---|---|---|
Jun. 30, 2025 |
Jun. 30, 2024 |
Dec. 31, 2024 |
|
| Basis of Preparation and Accounting Policies [Abstract] | |||
| Reconciliation net result effect of adjustment after tax EU IAS 39 carve-out | € 786 | € 1,099 | € 1,099 |