v3.26.1
Intangible Assets - Additional Information (Detail) - EUR (€)
€ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Disclosure of detailed information about intangible assets [Line Items]    
Goodwill € 313 € 345
Description of adjustments for impairment loss recognized in profit or loss goodwill An allowance has also been made for the present value of profits from expected new business in the next four years.  
Impairment loss recognized period intangible assets and goodwill 4 years  
Adjustments for impairment loss recognized in profit or loss, goodwill € 108  
Unallocated goodwill 1,375  
Aegon Investment Holdings Limited Groups subsidiary companies [Member]    
Disclosure of detailed information about intangible assets [Line Items]    
Goodwill 228  
United States [member] | Annuities cash generating units [member]    
Disclosure of detailed information about intangible assets [Line Items]    
Recoverable amount of assets - cash generating unit 121 137
United States [member] | Retirement plans cash generating unit [member]    
Disclosure of detailed information about intangible assets [Line Items]    
Recoverable amount of assets - cash generating unit € 68 € 77
Service concession rights [member]    
Disclosure of detailed information about intangible assets [Line Items]    
Average amortization period 10 and 30 years  
Remaining average amortization period 10 years 11 years
Software [member]    
Disclosure of detailed information about intangible assets [Line Items]    
Average amortization period three to five years  
Remaining average amortization period no  
Goodwill [member] | Bottom of range [member] | Transamerica Corporation [member]    
Disclosure of detailed information about intangible assets [Line Items]    
Pre-tax adjusted discount rate 3.46%  
Period over which economic available capital is calculated 1 month  
Goodwill [member] | Top of range [member] | Transamerica Corporation [member]    
Disclosure of detailed information about intangible assets [Line Items]    
Pre-tax adjusted discount rate 4.17%  
Period over which economic available capital is calculated 30 years  
Future Servicing Rights [Member]    
Disclosure of detailed information about intangible assets [Line Items]    
Remaining amortization of future servicing rights € 93 € 104
Remaining amortisation period of intangible assets material to entity 7 years 6 months