v3.26.1
Derivatives - Summary of Derivative Asset and Liability (Detail) - EUR (€)
€ in Millions
Dec. 31, 2025
Dec. 31, 2024
Disclosure of derivative financial instruments [Line Items]    
Derivative assets € 485 € 771
Derivative liabilities 1,469 2,435
Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 485 771
Derivative liabilities 1,469 2,435
Insurance Contracts With Direct Participating Features [member] | Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 20 66
Derivative liabilities 91 157
Insurance Contracts Without Direct Participating Features [member] | Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 441 616
Derivative liabilities 1,283 2,085
Investment Contracts With Direct Participating Features [member] | Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 14 53
Derivative liabilities 86 135
Non-Insurance related [member] | Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 10 36
Derivative liabilities 8 58
Other derivatives [member] | Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 390 606
Derivative liabilities 597 1,331
Other derivatives [member] | Insurance Contracts With Direct Participating Features [member] | Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 20 66
Derivative liabilities 91 157
Other derivatives [member] | Insurance Contracts Without Direct Participating Features [member] | Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 348 477
Derivative liabilities 412 983
Other derivatives [member] | Investment Contracts With Direct Participating Features [member] | Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 14 53
Derivative liabilities 86 135
Other derivatives [member] | Non-Insurance related [member] | Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 8 10
Derivative liabilities 8 56
Fair value hedges [member] | Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 4 3
Derivative liabilities 3 3
Fair value hedges [member] | Insurance Contracts With Direct Participating Features [member] | Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 0 0
Derivative liabilities 0 0
Fair value hedges [member] | Insurance Contracts Without Direct Participating Features [member] | Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 4 3
Derivative liabilities 3 3
Fair value hedges [member] | Investment Contracts With Direct Participating Features [member] | Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 0 0
Derivative liabilities 0 0
Fair value hedges [member] | Non-Insurance related [member] | Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 0 0
Derivative liabilities 0 0
Cash flow hedges [member] | Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 89 136
Derivative liabilities 869 1,100
Cash flow hedges [member] | Insurance Contracts With Direct Participating Features [member] | Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 0 0
Derivative liabilities 0 0
Cash flow hedges [member] | Insurance Contracts Without Direct Participating Features [member] | Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 89 136
Derivative liabilities 869 1,100
Cash flow hedges [member] | Investment Contracts With Direct Participating Features [member] | Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 0 0
Derivative liabilities 0 0
Cash flow hedges [member] | Non-Insurance related [member] | Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 0 0
Derivative liabilities 0 0
Net foreign investment hedges [member] | Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 2 26
Derivative liabilities 0 2
Net foreign investment hedges [member] | Insurance Contracts With Direct Participating Features [member] | Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 0 0
Derivative liabilities 0 0
Net foreign investment hedges [member] | Insurance Contracts Without Direct Participating Features [member] | Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 0 0
Derivative liabilities 0 0
Net foreign investment hedges [member] | Investment Contracts With Direct Participating Features [member] | Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 0 0
Derivative liabilities 0 0
Net foreign investment hedges [member] | Non-Insurance related [member] | Financial assets at fair value through profit or loss, mandatorily measured at fair value, category [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 2 26
Derivative liabilities 0 2
Aegon Risk [Member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 445 643
Derivative liabilities 1,285 2,129
Aegon Risk [Member] | Insurance Contracts With Direct Participating Features [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 0 0
Derivative liabilities 0 0
Aegon Risk [Member] | Insurance Contracts Without Direct Participating Features [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 441 616
Derivative liabilities 1,283 2,085
Aegon Risk [Member] | Investment Contracts With Direct Participating Features [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 0 0
Derivative liabilities 0 0
Aegon Risk [Member] | Non-Insurance related [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 4 26
Derivative liabilities 2 44
Policyholder Risk [Member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 40 129
Derivative liabilities 184 306
Policyholder Risk [Member] | Insurance Contracts With Direct Participating Features [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 20 66
Derivative liabilities 91 157
Policyholder Risk [Member] | Insurance Contracts Without Direct Participating Features [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 0 0
Derivative liabilities 0 0
Policyholder Risk [Member] | Investment Contracts With Direct Participating Features [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 14 53
Derivative liabilities 86 135
Policyholder Risk [Member] | Non-Insurance related [member]    
Disclosure of derivative financial instruments [Line Items]    
Derivative assets 6 10
Derivative liabilities € 6 € 14