v3.26.1
Financial Risks - Schedule of Credit Risk Concentration - Credit Rating (Detail) - EUR (€)
€ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Government bonds [member] | AAA [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating € 160 € 169
Government bonds [member] | AA [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 4,754 5,857
Government bonds [member] | A [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 777 823
Government bonds [member] | BBB [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 402 417
Government bonds [member] | BB [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 247 265
Government bonds [member] | B [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 19 53
Government bonds [member] | CCC or lower [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 15 18
Government bonds [member] | A credit rating [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating [1] 6,374 7,601
Corporate bonds [member] | AAA [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 536 434
Corporate bonds [member] | AA [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 2,413 2,686
Corporate bonds [member] | A [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 14,804 16,127
Corporate bonds [member] | BBB [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 17,264 20,099
Corporate bonds [member] | BB [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 672 834
Corporate bonds [member] | B [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 171 398
Corporate bonds [member] | CCC or lower [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 103 205
Corporate bonds [member] | A credit rating [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating [1] 35,963 40,783
RMBs CMBSs ABSs [member] | AAA [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 3,407 2,888
RMBs CMBSs ABSs [member] | AA [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 1,200 1,202
RMBs CMBSs ABSs [member] | A [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 3,573 3,169
RMBs CMBSs ABSs [member] | BBB [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 1,059 847
RMBs CMBSs ABSs [member] | BB [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 83 99
RMBs CMBSs ABSs [member] | B [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 154 94
RMBs CMBSs ABSs [member] | CCC or lower [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 439 503
RMBs CMBSs ABSs [member] | A credit rating [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating [1] 9,914 8,802
Other credit grades [member] | AAA [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 1,708 1,892
Other credit grades [member] | AA [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 0 0
Other credit grades [member] | A [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 0 0
Other credit grades [member] | BBB [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 0 0
Other credit grades [member] | BB [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 0 0
Other credit grades [member] | B [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 0 0
Other credit grades [member] | CCC or lower [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 0 0
Other credit grades [member] | Assets not rated [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 94 83
Other credit grades [member] | A credit rating [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating [1] 1,802 1,976
Debt securities and money market investments [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 94  
Debt securities and money market investments [member] | AAA [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 5,811 5,383 [2]
Debt securities and money market investments [member] | AA [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 8,367 9,745 [2]
Debt securities and money market investments [member] | A [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 19,154 20,119 [2]
Debt securities and money market investments [member] | BBB [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 18,725 21,363 [2]
Debt securities and money market investments [member] | BB [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 1,002 1,198 [2]
Debt securities and money market investments [member] | B [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 345 545 [2]
Debt securities and money market investments [member] | CCC or lower [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating 557 726 [2]
Debt securities and money market investments [member] | Assets not rated [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating [2]   83
Debt securities and money market investments [member] | A credit rating [member]    
Disclosure of credit risk exposure [line items]    
Credit risk concentrations credit rating [1] € 54,054 € 59,162
[1] CNLP Ratings are used and are the lower of the Barclay’s Rating, and the Internal Rating with the Barclay’s rating being a blended rating of S&P, Fitch, and Moody’s.
[2] Includes investments of Holding and other activities.