v3.26.1
Defined Benefit Plans - Summary of Actuarial Assumptions Used to Determine Defined Benefit Obligations (Detail)
Dec. 31, 2025
Dec. 31, 2024
Transamerica [member]    
Financial actuarial assumptions    
Salary increase rate 4.00% 4.00%
Health care trend rate 8.50% 6.90%
Transamerica [member] | Top of range [member]    
Financial actuarial assumptions    
Discount rate 5.45% 5.59%
Transamerica [member] | Bottom of range [member]    
Financial actuarial assumptions    
Discount rate 5.23% 5.51% [1]
Aegon United Kingdom [member]    
Financial actuarial assumptions    
Discount rate 5.66% 5.58%
Price inflation 3.00% 3.19%
Aegon Employees Netherlands B.V. [member]    
Financial actuarial assumptions    
Discount rate 4.00% 3.51%
Price inflation 2.13% 1.99%
[1] Transamerica has separate discount rates for all pension plans: 5.45% in 2025, 5.59% in 2024 and for post-retirement welfare plan: 5.23% in 2025, 5.51% in 2024.