v3.26.1
Deferred Tax - Additional Information (Detail) - EUR (€)
€ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Deferred tax assets and liabilities [Line Items]    
Deferred tax assets recognized for tax losses, gross € 1,894 € 2,439
Unused tax credits [member]    
Deferred tax assets and liabilities [Line Items]    
Deferred tax assets recognized for tax losses, tax 597 661
Tax losses and credits carried forward [member]    
Deferred tax assets and liabilities [Line Items]    
Deferred tax assets recognized for tax losses, gross 2,295 3,577
Deferred tax assets recognized for tax losses, tax € 515 € 787