v3.26.1
Earnings per share - Schedule of Profit Loss Attributable to the Owners of the Parent for Calculating Diluted Earnings Per Share (Detail) - EUR (€)
€ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Disclosure of profit loss attributable to the owners of the parent for calculating diluted earnings per share [line items]      
Loss attributable to owners of the parent € (95) € 15 € (905)
Assumed coupon on Perpetual Bonds (net of tax) (11) € (15) (36)
Total (106)   (941)
Class A Shares [Member]      
Disclosure of profit loss attributable to the owners of the parent for calculating diluted earnings per share [line items]      
Total [1] (88)   (781)
Class B Shares [Member]      
Disclosure of profit loss attributable to the owners of the parent for calculating diluted earnings per share [line items]      
Total [2] € (18)   € (160)
[1] Calculated as 83% of adjusted loss attributable to owners of the parent, based on the weight of the Class A weighted average number of shares out of the total shares.
[2] Calculated as 17% of adjusted loss attributable to owners of the parent, based on the weight of the Class B weighted average number of shares out of the total shares.