v3.26.1
Defined Benefit Plans - Summary of Movements of Defined Benefit Plans (Detail) - EUR (€)
€ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Disclosure of net defined benefit liability (asset) [Line Items]    
Beginning Balance € 457 € 546
Defined benefit expenses 61 57
Current year service cost 43 39
Interest expense 18 18
Remeasurements of the defined benefit obligations:    
Remeasurements of defined benefit plans (9) 15
Contributions paid (44) (148)
Benefits paid (31) (40)
Net exchange differences (50) 27
Ending Balance 384 457
Present value of defined benefit obligation [member]    
Disclosure of net defined benefit liability (asset) [Line Items]    
Beginning Balance 3,590 3,616
Current year service cost 43 39
Interest expense 177 173
Remeasurements of the defined benefit obligations:    
- Actuarial gains and losses arising from changes in demographic assumptions 21 6
- Actuarial gains and losses arising from changes in financial assumptions 14 (217)
Benefits paid (237) (237)
Net exchange differences (350) 208
Other 0 2
Ending Balance 3,257 3,590
Defined benefit plans [member]    
Disclosure of net defined benefit liability (asset) [Line Items]    
Beginning Balance 3,123 3,051
Interest expense 155 152
Remeasurements of the defined benefit obligations:    
Remeasurements of defined benefit plans 32 (208)
Contributions by employer 44 148
Benefits paid (210) (200)
Net exchange differences (299) 180
Ending Balance 2,845 3,123
Reimbursement Rights [Member]    
Disclosure of net defined benefit liability (asset) [Line Items]    
Beginning Balance 9 20
Interest expense 3 3
Remeasurements of the defined benefit obligations:    
- Actuarial gains and losses arising from changes in financial assumptions 12 (18)
Benefits paid 4 4
Other 0 2
Ending Balance 28 9
Retirement Benefit Plans [member]    
Disclosure of net defined benefit liability (asset) [Line Items]    
Beginning Balance 269 368
Defined benefit expenses 45 42
Current year service cost 36 32
Interest expense 9 9
Remeasurements of the defined benefit obligations:    
Remeasurements of defined benefit plans (6) 19
Contributions paid (44) (148)
Benefits paid (19) (28)
Net exchange differences (28) 16
Ending Balance 217 269
Other Post Employment Benefit Plans [member]    
Disclosure of net defined benefit liability (asset) [Line Items]    
Beginning Balance 189 178
Defined benefit expenses 15 15
Current year service cost 7 7
Interest expense 9 9
Remeasurements of the defined benefit obligations:    
Remeasurements of defined benefit plans (3) (5)
Contributions paid 0 0
Benefits paid (12) (12)
Net exchange differences (22) 12
Ending Balance 167 189
Aegon Ltd. [member]    
Disclosure of net defined benefit liability (asset) [Line Items]    
Beginning Balance 53  
Defined benefit expenses 2 2
Remeasurements of the defined benefit obligations:    
Remeasurements of defined benefit plans (3) (2)
Transfer from AEN   53
Other (1)  
Ending Balance 51 53
Aegon Ltd. [member] | Retirement Benefit Plans [member]    
Disclosure of net defined benefit liability (asset) [Line Items]    
Beginning Balance 50  
Defined benefit expenses 2 2
Remeasurements of the defined benefit obligations:    
Remeasurements of defined benefit plans (3) (1)
Transfer from AEN   49
Ending Balance 49 50
Aegon Ltd. [member] | Other Post Employment Benefit Plans [member]    
Disclosure of net defined benefit liability (asset) [Line Items]    
Beginning Balance 3  
Remeasurements of the defined benefit obligations:    
Remeasurements of defined benefit plans   (1)
Transfer from AEN   4
Other (1)  
Ending Balance € 2 € 3