Earnings per share - Schedule of Profit Loss Attributable to the Owners of the Parent for Calculating Basic 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 basic earnings per share [line items]

Profit / (loss) attributable to owners of the parent

€ (95)

€ 15

€ (905)

Assumed coupon on Perpetual Bond (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 basic 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 basic 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.