v3.26.1
Discontinued operations - Summary of Investment contracts without discretionary participation features (Detail) - Without Discretionary Participation Features [member] - EUR (€)
€ in Millions
 6 Months Ended 12 Months Ended
Jun. 30, 2026
Dec. 31, 2025
Aegon Risk [Member]    
Disclosure of investment contracts general and separate accounts [Line Items]    
Beginning balance on January 1 € 12,652 € 12,592
Deposits 816 1,798
Withdrawals (840) (1,653)
Interest credited 180 354
Net exchange differences 362 (1,535)
Ending balance 13,570 12,652
Aegon Risk [Member] | Discontinued operations [member]    
Disclosure of investment contracts general and separate accounts [Line Items]    
Beginning balance on January 1 0  
Transfers to disposal groups 31  
Deposits 1  
Withdrawals (2)  
Interest credited 0  
Fund charges released 0  
Net exchange differences 0  
Ending balance 31 0
Policyholder Risk [Member]    
Disclosure of investment contracts general and separate accounts [Line Items]    
Beginning balance on January 1 85,161 79,078
Deposits 4,875 15,135
Withdrawals (4,279) (12,788)
Interest credited 1,033 11,004
Fund charges released (154) (384)
Net exchange differences 1,121 (6,241)
Ending balance 28,269 85,161
Policyholder Risk [Member] | Discontinued operations [member]    
Disclosure of investment contracts general and separate accounts [Line Items]    
Beginning balance on January 1 0  
Transfers to disposal groups 59,035  
Deposits 2,637  
Withdrawals (1,572)  
Interest credited 6,882  
Fund charges released (48)  
Net exchange differences 474  
Ending balance € 67,408 € 0