v3.26.1
Deferred Tax - Schedule of Net Deferred Tax Assets and Liabilities has been Recognized (Detail) - EUR (€)
€ in Millions
 12 Months Ended
Dec. 31, 2025
Dec. 31, 2024
Dec. 31, 2023
Deferred tax assets and liabilities [Line Items]      
Beginning balance € 2,375 € 2,293  
Acquisitions / Additions (1) (10)  
Charged to income statement (22) 15 € 204
Charged to OCI (201) (75)  
Net exchange differences (270) 151  
Disposal of a business   1  
Transfer to/from other headings 0    
Ending balance 1,882 2,375 2,293
Financial assets [member]      
Deferred tax assets and liabilities [Line Items]      
Beginning balance 1,066 808  
Acquisitions / Additions 0 0  
Charged to income statement (141) (76)  
Charged to OCI (358) 278  
Net exchange differences (108) 63  
Disposal of a business   (7)  
Transfer to/from other headings 8    
Ending balance 467 1,066 808
Insurance contracts [member]      
Deferred tax assets and liabilities [Line Items]      
Beginning balance (1,180) (661)  
Acquisitions / Additions 0 0  
Charged to income statement 574 (109)  
Charged to OCI 152 (354)  
Net exchange differences 110 (63)  
Disposal of a business   7  
Transfer to/from other headings 0    
Ending balance (344) (1,180) (661)
Deferred expenses and other intangible assets [member]      
Deferred tax assets and liabilities [Line Items]      
Beginning balance 576 537  
Acquisitions / Additions (1) (10)  
Charged to income statement (50) 12  
Charged to OCI 0 0  
Net exchange differences (67) 36  
Disposal of a business   0  
Transfer to/from other headings 0    
Ending balance 459 576 537
Defined benefit plans [member]      
Deferred tax assets and liabilities [Line Items]      
Beginning balance 237 214  
Acquisitions / Additions 0 0  
Charged to income statement (9) 12  
Charged to OCI 2 (3)  
Net exchange differences (28) 15  
Disposal of a business   0  
Transfer to/from other headings 0    
Ending balance 203 237 214
Tax losses and credits carried forward [member]      
Deferred tax assets and liabilities [Line Items]      
Beginning balance 1,448 1,112  
Acquisitions / Additions 0 0  
Charged to income statement (189) 259  
Charged to OCI 2 (4)  
Net exchange differences (148) 81  
Disposal of a business   0  
Transfer to/from other headings 0    
Ending balance 1,113 1,448 1,112
Other [member]      
Deferred tax assets and liabilities [Line Items]      
Beginning balance 228 284  
Acquisitions / Additions 0 0  
Charged to income statement (207) (83)  
Charged to OCI 0 8  
Net exchange differences (30) 19  
Disposal of a business   0  
Transfer to/from other headings (8)    
Ending balance € (17) € 228 € 284