Earnings per share - Additional Information (Detail) € / shares in Units, € in Millions |
12 Months Ended | |||
|---|---|---|---|---|
|
Dec. 31, 2025
EUR (€)
€ / shares
|
Dec. 31, 2024
EUR (€)
€ / shares
|
Dec. 31, 2023
$ / shares
|
Dec. 31, 2023
EUR (€)
€ / shares
|
|
| Earnings per share [line items] | ||||
| Amount of income tax coupon accrual | € | € 11 | € 15 | € 36 | |
| Class A Shares [Member] | ||||
| Earnings per share [line items] | ||||
| Basic loss per share | € (260,000) | € 0 | € (2,140,000) | |
| Diluted loss per share | (260,000) | 0 | (2,120,000) | |
| Basic earnings (loss)/gain per share | (per share) | 0 | $ (2.14) | ||
| Diluted earnings (loss)/gain per share | (per share) | 0 | (2.14) | ||
| Class B Shares [Member] | ||||
| Earnings per share [line items] | ||||
| Basic loss per share | (100,000) | 0 | (860,000) | |
| Diluted loss per share | € (100,000) | 0 | € (860,000) | |
| Basic earnings (loss)/gain per share | (per share) | 0 | (0.86) | ||
| Diluted earnings (loss)/gain per share | (per share) | € 0 | $ (0.86) | ||