v3.26.1
Revenue From Contracts With Customers - Schedule of Group's Revenue from External Customers (Detail) - EUR (€)
€ in Millions
12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Disclosure of disaggregation of revenue from contracts with customers [line items]      
Revenue € 2,627 € 2,001 € 2,030
LUXEMBOURG      
Disclosure of disaggregation of revenue from contracts with customers [line items]      
Revenue 249 79 49
UNITED STATES      
Disclosure of disaggregation of revenue from contracts with customers [line items]      
Revenue 1,023 713 759
GERMANY      
Disclosure of disaggregation of revenue from contracts with customers [line items]      
Revenue 309 321 329
UNITED KINGDOM      
Disclosure of disaggregation of revenue from contracts with customers [line items]      
Revenue 149 203 214
FRANCE      
Disclosure of disaggregation of revenue from contracts with customers [line items]      
Revenue 89 74 78
Europe [Member]      
Disclosure of disaggregation of revenue from contracts with customers [line items]      
Revenue 255 205 205
Others [Member]      
Disclosure of disaggregation of revenue from contracts with customers [line items]      
Revenue € 553 € 406 € 396