v3.26.1
Other Equity Instruments - Summary of Other Equity Instruments (Detail) - EUR (€)
€ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Disclosure of other equity instruments [line items]      
Beginning balance € 1,972 € 1,951 € 1,943
Shares granted / Share options cost incurred 37 49 33
Shares vested / Share options forfeited (31) (28) (25)
Ending balance 1,978 1,972 1,951
Share options and incentive plans [member]      
Disclosure of other equity instruments [line items]      
Beginning balance [1] 95 74 66
Shares granted / Share options cost incurred [1] 37 49 33
Shares vested / Share options forfeited [1] (31) (28) (25)
Ending balance [1] 101 95 74
Perpetual contingent convertible securities [member]      
Disclosure of other equity instruments [line items]      
Beginning balance 500 500 500
Ending balance 500 500 500
Junior perpetual capital securities [member]      
Disclosure of other equity instruments [line items]      
Beginning balance 923 923 923
Ending balance 923 923 923
Perpetual cumulative subordinated bonds [member]      
Disclosure of other equity instruments [line items]      
Beginning balance 454 454 454
Ending balance € 454 € 454 € 454
[1] Incentive plans include the shares granted to personnel that are not yet vested