v3.26.1
(Re)Insurance contracts and investment contracts with discretionary participation features - Summary of New Contracts Recognized (Detail) - EUR (€)
€ in Millions
12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Insurance contracts issued [member]    
Disclosure In Tabular Form Of New Contracts Recognized Insurance During The Period [Line Items]    
Total € 42 € 54
Insurance contracts issued [member] | Present value of cash inflows [member]    
Disclosure In Tabular Form Of New Contracts Recognized Insurance During The Period [Line Items]    
Total (6,680) (6,225)
Insurance contracts issued [member] | Present value of cash outflows [member]    
Disclosure In Tabular Form Of New Contracts Recognized Insurance During The Period [Line Items]    
Total 5,917 5,612
Insurance contracts issued [member] | Risk adjustment for non-financial risk [member]    
Disclosure In Tabular Form Of New Contracts Recognized Insurance During The Period [Line Items]    
Total 135 120
Insurance contracts issued [member] | Contractual service margin [member]    
Disclosure In Tabular Form Of New Contracts Recognized Insurance During The Period [Line Items]    
Total 669 546
Insurance contracts issued [member] | Non Onerous Insurance Contracts [Member]    
Disclosure In Tabular Form Of New Contracts Recognized Insurance During The Period [Line Items]    
Issued non-onerous contracts 0 0
Insurance contracts issued [member] | Non Onerous Insurance Contracts [Member] | Present value of cash inflows [member]    
Disclosure In Tabular Form Of New Contracts Recognized Insurance During The Period [Line Items]    
Issued non-onerous contracts (5,661) (5,363)
Insurance contracts issued [member] | Non Onerous Insurance Contracts [Member] | Present value of cash outflows [member]    
Disclosure In Tabular Form Of New Contracts Recognized Insurance During The Period [Line Items]    
Issued non-onerous contracts 4,873 4,715
Insurance contracts issued [member] | Non Onerous Insurance Contracts [Member] | Risk adjustment for non-financial risk [member]    
Disclosure In Tabular Form Of New Contracts Recognized Insurance During The Period [Line Items]    
Issued non-onerous contracts 118 102
Insurance contracts issued [member] | Non Onerous Insurance Contracts [Member] | Contractual service margin [member]    
Disclosure In Tabular Form Of New Contracts Recognized Insurance During The Period [Line Items]    
Issued non-onerous contracts 669 546
Insurance contracts issued [member] | Onerous Insurance Contracts [Member]    
Disclosure In Tabular Form Of New Contracts Recognized Insurance During The Period [Line Items]    
Issued onerous contracts 42 54
Insurance contracts issued [member] | Onerous Insurance Contracts [Member] | Present value of cash inflows [member]    
Disclosure In Tabular Form Of New Contracts Recognized Insurance During The Period [Line Items]    
Issued onerous contracts (1,019) (861)
Insurance contracts issued [member] | Onerous Insurance Contracts [Member] | Present value of cash outflows [member]    
Disclosure In Tabular Form Of New Contracts Recognized Insurance During The Period [Line Items]    
Issued onerous contracts 1,044 897
Insurance contracts issued [member] | Onerous Insurance Contracts [Member] | Risk adjustment for non-financial risk [member]    
Disclosure In Tabular Form Of New Contracts Recognized Insurance During The Period [Line Items]    
Issued onerous contracts 17 18
Insurance contracts issued [member] | Onerous Insurance Contracts [Member] | Contractual service margin [member]    
Disclosure In Tabular Form Of New Contracts Recognized Insurance During The Period [Line Items]    
Issued onerous contracts 0 0
Reinsurance contracts held [member] | Present value of cash inflows [member]    
Disclosure In Tabular Form Of New Contracts Recognized Insurance During The Period [Line Items]    
Issued non-onerous contracts 3,284 54
Reinsurance contracts held [member] | Present value of cash outflows [member]    
Disclosure In Tabular Form Of New Contracts Recognized Insurance During The Period [Line Items]    
Issued non-onerous contracts (3,484) (65)
Reinsurance contracts held [member] | Risk adjustment for non-financial risk [member]    
Disclosure In Tabular Form Of New Contracts Recognized Insurance During The Period [Line Items]    
Issued non-onerous contracts 60 4
Reinsurance contracts held [member] | Contractual service margin [member]    
Disclosure In Tabular Form Of New Contracts Recognized Insurance During The Period [Line Items]    
Issued non-onerous contracts 141 8
Reinsurance contracts held [member] | Income recognised on initial recognition [member]    
Disclosure In Tabular Form Of New Contracts Recognized Insurance During The Period [Line Items]    
Issued non-onerous contracts € 1 € 1