v3.26.1
Total Net Investment Result - Summary of Insurance Net Investment Result (Detail) - EUR (€)
€ in Millions
 6 Months Ended 12 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Dec. 31, 2025
Disclosure of insurance and reinsurance net investment result [Line items]      
Interest revenue on financial instruments calculated using the effective interest method € 1,542 € 1,658  
Impairment (losses) / reversals (20) 2  
Gains / (losses) on investments in equity instruments (FVOCI) 0 (1)  
Total insurance investment return [1] 4,611    
Amounts recognized in profit or loss (6,657) [1] (5,097) [2]  
Amounts recognized in OCI 398 [1] (433) [2]  
Amounts recognized in profit or loss 332 [1] 267 [2]  
Amounts recognized in OCI (169) [1] 62 [2]  
Insurance net investment result (29) [1] 843 [2]  
Amounts recognized in profit or loss 313 [1] 393 [2]  
Amounts recognized in OCI (341) [1] 450 [2]  
Insurance contracts issued [member]      
Disclosure of insurance and reinsurance net investment result [Line items]      
Total insurance/ reinsurance finance income / (expenses) (6,259) [1] (5,530) [2]  
Insurance contracts issued [member] | General model [member]      
Disclosure of insurance and reinsurance net investment result [Line items]      
Interest accreted to insurance / reinsurance contracts (1,488) [1] (1,533) [2]  
Interest rate and other financial assumption changes (208) [1] (827) [2]  
Revaluation of changes in non-financial assumptions and experience adjustments to current interest rates 50 [1] 150 [2]  
Insurance contracts issued [member] | Variable fee approach [member]      
Disclosure of insurance and reinsurance net investment result [Line items]      
Change in fair value of underlying assets (5,228) [1] (3,637) [2]  
Change in fulfillment value - risk mitigation option 615 [1] 318 [2] € 318
Reinsurance contracts held [member]      
Disclosure of insurance and reinsurance net investment result [Line items]      
Interest accreted to insurance / reinsurance contracts 339 [1] 280 [2]  
Interest rate and other financial assumption changes (134) [1] 102 [2]  
Revaluation of changes in non-financial assumptions and experience adjustments to current interest rates (35) [1] (54) [2]  
Changes in risk of non-performance of reinsurers (7) [1] 1 [2]  
Total insurance/ reinsurance finance income / (expenses) 163 [1] 329 [2]  
Insurance Contracts With Direct Participating Features [Member]      
Disclosure of insurance and reinsurance net investment result [Line items]      
Amounts recognized in profit or loss (4,616) [1] (3,324) [2]  
Amounts recognized in OCI 3 [1] 4 [2]  
Insurance net investment result (2) [1] 385 [2]  
Amounts recognized in profit or loss (5) [1] 381 [2]  
Amounts recognized in OCI 3 [1] 4 [2]  
Insurance Contracts With Direct Participating Features [Member] | Insurance contracts issued [member]      
Disclosure of insurance and reinsurance net investment result [Line items]      
Total insurance/ reinsurance finance income / (expenses) (4,613) [1] (3,320) [2]  
Insurance Contracts With Direct Participating Features [Member] | Insurance contracts issued [member] | Variable fee approach [member]      
Disclosure of insurance and reinsurance net investment result [Line items]      
Change in fair value of underlying assets (5,228) [1] (3,637) [2]  
Change in fulfillment value - risk mitigation option 615 [1] 318 [2]  
Insurance Contracts Without Direct Participating Features [Member]      
Disclosure of insurance and reinsurance net investment result [Line items]      
Amounts recognized in profit or loss (2,041) [1] (1,773) [2]  
Amounts recognized in OCI 396 [1] (437) [2]  
Amounts recognized in profit or loss 332 [1] 267 [2]  
Amounts recognized in OCI (169) [1] 62 [2]  
Insurance net investment result (25) [1] 457 [2]  
Amounts recognized in profit or loss 318 [1] 12 [2]  
Amounts recognized in OCI (343) [1] 446 [2]  
Insurance Contracts Without Direct Participating Features [Member] | Insurance contracts issued [member]      
Disclosure of insurance and reinsurance net investment result [Line items]      
Total insurance/ reinsurance finance income / (expenses) (1,645) [1] (2,210) [2]  
Insurance Contracts Without Direct Participating Features [Member] | Insurance contracts issued [member] | General model [member]      
Disclosure of insurance and reinsurance net investment result [Line items]      
Interest accreted to insurance / reinsurance contracts (1,488) [1] (1,533) [2]  
Interest rate and other financial assumption changes (207) [1] (827) [2]  
Revaluation of changes in non-financial assumptions and experience adjustments to current interest rates 50 [1] 150 [2]  
Insurance Contracts Without Direct Participating Features [Member] | Reinsurance contracts held [member]      
Disclosure of insurance and reinsurance net investment result [Line items]      
Interest accreted to insurance / reinsurance contracts 339 [1] 280 [2]  
Interest rate and other financial assumption changes (134) [1] 102 [2]  
Revaluation of changes in non-financial assumptions and experience adjustments to current interest rates (35) [1] (54) [2]  
Changes in risk of non-performance of reinsurers (7) [1] 1 [2]  
Total insurance/ reinsurance finance income / (expenses) 163 [1] 329 [2]  
Insurance investment return [member]      
Disclosure of insurance and reinsurance net investment result [Line items]      
Interest revenue on financial instruments calculated using the effective interest method 1,231 [1] 1,364 [2]  
Interest income from instruments measured at FVPL 105 [1] 111 [2]  
Other investment income 6 [1] 7 [2]  
Results from financial transactions 5,318 [1] 3,814 [2]  
Impairment (losses) / reversals 16 [1] (1) [2]  
Interest expenses (39) [1] (73) [2]  
Profit or loss impacts 6,637 [1] 5,223 [2]  
Gains / (losses) on investments in equity instruments (FVOCI) [2]   (1)  
Unrealized gains / (losses) on financial assets (FVOCI) (565) [1] 745 [2]  
Realized gains / (losses) on disposal of financial assets (FVOCI) (5) [1] 76 [2]  
OCI impacts (570) [1] 821 [2]  
Total insurance investment return 6,067 [1] 6,044 [2]  
Insurance investment return [member] | Insurance Contracts With Direct Participating Features [Member]      
Disclosure of insurance and reinsurance net investment result [Line items]      
Results from financial transactions 4,610 [1] 3,705 [2]  
Profit or loss impacts 4,611 [1] 3,705 [2]  
Total insurance investment return [2]   3,705  
Insurance investment return [member] | Insurance Contracts Without Direct Participating Features [Member]      
Disclosure of insurance and reinsurance net investment result [Line items]      
Interest revenue on financial instruments calculated using the effective interest method 1,231 [1] 1,364 [2]  
Interest income from instruments measured at FVPL 105 [1] 111 [2]  
Other investment income 5 [1] 7 [2]  
Results from financial transactions 708 [1] 110 [2]  
Impairment (losses) / reversals 16 [1] (1) [2]  
Interest expenses (39) [1] (73) [2]  
Profit or loss impacts 2,027 [1] 1,517 [2]  
Gains / (losses) on investments in equity instruments (FVOCI) [2]   (1)  
Unrealized gains / (losses) on financial assets (FVOCI) (565) [1] 745 [2]  
Realized gains / (losses) on disposal of financial assets (FVOCI) (5) [1] 76 [2]  
OCI impacts (570) [1] 821 [2]  
Total insurance investment return € 1,457 [1] € 2,338 [2]  
[1] Investment contracts with DPF - Without direct part. includes EUR (2) million in line Total insurance finance income / (expenses) and Insurance net investment result.
[2] 1H 2025 figures are restated as Aegon UK is classified as discontinued operations.