Shareholders' equity - Schedule of disclosure of treasury shares in consolidated statement of financial position (Detail) - EUR (€) € in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
|
| Disclosure Of Treasury Shares In Consolidated Statement Of Financial Position And Are Carried At Acquisition Cost [Line Items] | |||
| Shares held at 31 december | 26,510,592 | 27,851,115 | 9,615,110 |
| Carrying value of shares held | € 156 | € 173 | € 90 |
| Class B Ordinary Shares [Member] | |||
| Disclosure Of Treasury Shares In Consolidated Statement Of Financial Position And Are Carried At Acquisition Cost [Line Items] | |||
| Shares held at 31 december | 11,976,209 | 11,976,209 | 0 |
| Carrying value of shares held | € 25 | € 25 | € 0 |