Segment Information - Summary of Reconciliation from Operating Result Before Tax to Income Before Tax (Parenthetical) (Detail) - EUR (€) € in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
|
| Disclosure of reconciliation from operating result before tax to income before tax [Line Items] | ||
| Experience adjustments that relate to current service included in other income charges | € 122 | € 5 |
| Gain (loss) on reversal of onerous contracts | 27 | 57 |
| Other income / (charges) [member] | ||
| Disclosure of reconciliation from operating result before tax to income before tax [Line Items] | ||
| Loss on onerous contracts | 217 | 472 |
| Insurance contracts issued [member] | ||
| Disclosure of reconciliation from operating result before tax to income before tax [Line Items] | ||
| Gain (loss) on changes in discount rates | € 802 | € 440 |