Shareholders' Equity - Summary of Share Premium (Detail) - EUR (€) € in Millions |
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
|---|---|---|---|
| Disclosure of share premium [Line Items] | |||
| Beginning balance | € 6,853 | € 6,853 | € 6,853 |
| Ending balance | 6,853 | 6,853 | 6,853 |
| Common shares [member] | |||
| Disclosure of share premium [Line Items] | |||
| Beginning balance | 5,200 | 5,200 | |
| Ending balance | 5,200 | 5,200 | 5,200 |
| Common share B [member] | |||
| Disclosure of share premium [Line Items] | |||
| Beginning balance | 1,653 | 1,653 | |
| Ending balance | € 1,653 | € 1,653 | € 1,653 |