Shareholders' Equity - Summary of Remeasurement of Defined Benefit Plans (Detail) - EUR (€) € in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
|
| Disclosure of revaluation reserve [Line Items] | |||
| Disposal of a business | € 2 | € 12 | € 45 |
| Remeasurement of defined benefit Plans of group companies [member] | |||
| Disclosure of revaluation reserve [Line Items] | |||
| At January 1 | (1,072) | (1,006) | (1,565) |
| Remeasurements of defined benefit plans | 9 | (6) | (110) |
| Tax effect | (4) | 1 | 17 |
| Net exchange differences | 101 | (60) | 14 |
| Disposal of a business | 0 | 0 | 638 |
| Total remeasurement of defined benefit plans | € (966) | € (1,072) | € (1,006) |