v3.26.1
Segment Information - Summary of Detailed Information About Insurance, Reinsurance and Investment Contracts (Detail) - EUR (€)
€ in Millions
Dec. 31, 2025
Dec. 31, 2024
Disclosure Of Detailed Information About Insurance Reinsurance And Investment Contracts Assets and Liabilities Per Segment [Line Items]    
Insurance contracts € 176,049 € 188,233
Investment contracts liabilities 97,814 91,669
Insurance contracts and investment contracts without participation features 197,331 210,565
Reinsurance contracts held 16,958 15,719
Eliminations [member]    
Disclosure Of Detailed Information About Insurance Reinsurance And Investment Contracts Assets and Liabilities Per Segment [Line Items]    
Insurance contracts and investment contracts without participation features (4,292) (5,219)
Reinsurance contracts held (4,106) (5,133)
International [member]    
Disclosure Of Detailed Information About Insurance Reinsurance And Investment Contracts Assets and Liabilities Per Segment [Line Items]    
Insurance contracts and investment contracts without participation features 5,220 6,239
Reinsurance contracts held 3,981 4,975
Americas [member]    
Disclosure Of Detailed Information About Insurance Reinsurance And Investment Contracts Assets and Liabilities Per Segment [Line Items]    
Insurance contracts and investment contracts without participation features 130,429 142,874
Reinsurance contracts held 17,086 15,878
United Kingdom [member]    
Disclosure Of Detailed Information About Insurance Reinsurance And Investment Contracts Assets and Liabilities Per Segment [Line Items]    
Insurance contracts and investment contracts without participation features 65,974 66,671
Reinsurance contracts held (3) (2)
Direct Participating Contracts [member]    
Disclosure Of Detailed Information About Insurance Reinsurance And Investment Contracts Assets and Liabilities Per Segment [Line Items]    
Insurance contracts 111,508 118,409
Direct Participating Contracts [member] | International [member]    
Disclosure Of Detailed Information About Insurance Reinsurance And Investment Contracts Assets and Liabilities Per Segment [Line Items]    
Insurance contracts 246 219
Direct Participating Contracts [member] | Americas [member]    
Disclosure Of Detailed Information About Insurance Reinsurance And Investment Contracts Assets and Liabilities Per Segment [Line Items]    
Insurance contracts 67,074 74,446
Direct Participating Contracts [member] | United Kingdom [member]    
Disclosure Of Detailed Information About Insurance Reinsurance And Investment Contracts Assets and Liabilities Per Segment [Line Items]    
Insurance contracts 44,188 43,744
Without Direct Participating Contracts [member]    
Disclosure Of Detailed Information About Insurance Reinsurance And Investment Contracts Assets and Liabilities Per Segment [Line Items]    
Insurance contracts 64,497 69,784
Investment contracts liabilities 12  
Without Direct Participating Contracts [member] | Eliminations [member]    
Disclosure Of Detailed Information About Insurance Reinsurance And Investment Contracts Assets and Liabilities Per Segment [Line Items]    
Insurance contracts (4,292) (5,219)
Without Direct Participating Contracts [member] | International [member]    
Disclosure Of Detailed Information About Insurance Reinsurance And Investment Contracts Assets and Liabilities Per Segment [Line Items]    
Insurance contracts 4,918 5,980
Investment contracts liabilities 12  
Without Direct Participating Contracts [member] | Americas [member]    
Disclosure Of Detailed Information About Insurance Reinsurance And Investment Contracts Assets and Liabilities Per Segment [Line Items]    
Insurance contracts 63,355 68,428
Without Direct Participating Contracts [member] | United Kingdom [member]    
Disclosure Of Detailed Information About Insurance Reinsurance And Investment Contracts Assets and Liabilities Per Segment [Line Items]    
Insurance contracts 517 595
Contracts measured under the PAA [member]    
Disclosure Of Detailed Information About Insurance Reinsurance And Investment Contracts Assets and Liabilities Per Segment [Line Items]    
Insurance contracts 44 41
Contracts measured under the PAA [member] | International [member]    
Disclosure Of Detailed Information About Insurance Reinsurance And Investment Contracts Assets and Liabilities Per Segment [Line Items]    
Insurance contracts 44 41
Discretionary Participation Features [member]    
Disclosure Of Detailed Information About Insurance Reinsurance And Investment Contracts Assets and Liabilities Per Segment [Line Items]    
Investment contracts liabilities 21,269 22,332
Discretionary Participation Features [member] | United Kingdom [member]    
Disclosure Of Detailed Information About Insurance Reinsurance And Investment Contracts Assets and Liabilities Per Segment [Line Items]    
Investment contracts liabilities € 21,269 € 22,332