v3.26.1
Financial Risks - Summary of Equity Real Estate and Other Non-fixed-income Portfolio (Detail) - EUR (€)
€ in Millions
Dec. 31, 2025
Dec. 31, 2024
Americas [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk € 4,249 € 4,785
United Kingdom [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 731 730
International [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 75 56
Equity funds [member] | Americas [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 131 145
Common shares [member] | Americas [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 70 95
Common shares [member] | United Kingdom [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 16 14
Common shares [member] | International [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 6 5
Preferred shares [member] | Americas [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 10 16
Investments in real estate [member] | Americas [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 24 40
Investments in real estate [member] | International [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 19 17
Hedge funds [member] | Americas [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 4 7
Other alternative investments [member] | Americas [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 2,468 2,682
Other alternative investments [member] | International [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 2  
Other financial asset [member] | Americas [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 1,542 1,800
Other financial asset [member] | United Kingdom [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 714 716
Other financial asset [member] | International [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 49 33
Asset management [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 10 10
Asset management [member] | Equity funds [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 9 9
Asset management [member] | Other financial asset [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 1 2
Holding and other activities [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 5,065 5,582
Holding and other activities [member] | Equity funds [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 140 154
Holding and other activities [member] | Common shares [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 92 114
Holding and other activities [member] | Preferred shares [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 10 16
Holding and other activities [member] | Investments in real estate [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 42 57
Holding and other activities [member] | Hedge funds [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 4 7
Holding and other activities [member] | Other alternative investments [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk 2,470 2,682
Holding and other activities [member] | Other financial asset [member]    
General account equity, real estate and other non-fixed-income portfolio [line items]    
Maximum exposure of equity market risk and other investments risk € 2,306 € 2,551