v3.26.1
(Re)Insurance contracts and investment contracts with discretionary participation features - Summary of Maturity Analysis Contractual Service Margin (Detail) - Insurance contracts other than those to which premium allocation approach has been applied [member] - EUR (€)
€ in Millions
Dec. 31, 2025
Dec. 31, 2024
Insurance contracts issued [member]    
Disclosure of information about expected recognition of contractual service margin in profit or loss [line items]    
Contractual service margin after tax € 8,406 € 8,964
Insurance contracts issued [member] | Not later than 1 year [member]    
Disclosure of information about expected recognition of contractual service margin in profit or loss [line items]    
Contractual service margin after tax 864 922
Insurance contracts issued [member] | 1-2 years [member]    
Disclosure of information about expected recognition of contractual service margin in profit or loss [line items]    
Contractual service margin after tax 780 832
Insurance contracts issued [member] | 2-3 years [member]    
Disclosure of information about expected recognition of contractual service margin in profit or loss [line items]    
Contractual service margin after tax 705 752
Insurance contracts issued [member] | 3-4 years [member]    
Disclosure of information about expected recognition of contractual service margin in profit or loss [line items]    
Contractual service margin after tax 638 679
Insurance contracts issued [member] | 4-5 years [member]    
Disclosure of information about expected recognition of contractual service margin in profit or loss [line items]    
Contractual service margin after tax 577 614
Insurance contracts issued [member] | 5-10 years [member]    
Disclosure of information about expected recognition of contractual service margin in profit or loss [line items]    
Contractual service margin after tax 2,108 2,261
Insurance contracts issued [member] | 10-20 years [member]    
Disclosure of information about expected recognition of contractual service margin in profit or loss [line items]    
Contractual service margin after tax 1,856 2,009
Insurance contracts issued [member] | Later than 20 years [member]    
Disclosure of information about expected recognition of contractual service margin in profit or loss [line items]    
Contractual service margin after tax 879 896
Reinsurance contracts held [member]    
Disclosure of information about expected recognition of contractual service margin in profit or loss [line items]    
Contractual service margin after tax 585 237
Reinsurance contracts held [member] | Not later than 1 year [member]    
Disclosure of information about expected recognition of contractual service margin in profit or loss [line items]    
Contractual service margin after tax 37 0
Reinsurance contracts held [member] | 1-2 years [member]    
Disclosure of information about expected recognition of contractual service margin in profit or loss [line items]    
Contractual service margin after tax 36 1
Reinsurance contracts held [member] | 2-3 years [member]    
Disclosure of information about expected recognition of contractual service margin in profit or loss [line items]    
Contractual service margin after tax 35 4
Reinsurance contracts held [member] | 3-4 years [member]    
Disclosure of information about expected recognition of contractual service margin in profit or loss [line items]    
Contractual service margin after tax 34 6
Reinsurance contracts held [member] | 4-5 years [member]    
Disclosure of information about expected recognition of contractual service margin in profit or loss [line items]    
Contractual service margin after tax 34 7
Reinsurance contracts held [member] | 5-10 years [member]    
Disclosure of information about expected recognition of contractual service margin in profit or loss [line items]    
Contractual service margin after tax 146 49
Reinsurance contracts held [member] | 10-20 years [member]    
Disclosure of information about expected recognition of contractual service margin in profit or loss [line items]    
Contractual service margin after tax 172 106
Reinsurance contracts held [member] | Later than 20 years [member]    
Disclosure of information about expected recognition of contractual service margin in profit or loss [line items]    
Contractual service margin after tax € 91 € 63