v3.26.1
Financial Risks - Summary of Maturity Analysis Gross Undiscounted Contractual Cash Flows (Detail) - EUR (€)
€ in Millions
Dec. 31, 2025
Dec. 31, 2024
Disclosure of maturity analysis for financial assets held for managing liquidity risk [line items]    
Trust pass-through securities € 99 € 113
Borrowings 1,982 3,013
Lease liabilities 187 216
Contractual maturities of each category of financial liabilities [member]    
Disclosure of maturity analysis for financial assets held for managing liquidity risk [line items]    
Trust pass-through securities 156 187
Subordinated loans 2,529 2,954
Borrowings 1,956 3,762
Investment contracts 97,290 91,095
Lease liabilities 219 261
Other financial liabilities 4,016 4,307
On demand [member] | Contractual maturities of each category of financial liabilities [member]    
Disclosure of maturity analysis for financial assets held for managing liquidity risk [line items]    
Investment contracts 38,487 39,959
Other financial liabilities 2,877 3,419
Not later than 1 year [member] | Contractual maturities of each category of financial liabilities [member]    
Disclosure of maturity analysis for financial assets held for managing liquidity risk [line items]    
Trust pass-through securities 83 10
Subordinated loans 78 88
Borrowings 94 1,155
Investment contracts 58,621 50,922
Lease liabilities 31 37
Other financial liabilities 1,099 856
Later than one year and not later than two years [member] | Contractual maturities of each category of financial liabilities [member]    
Disclosure of maturity analysis for financial assets held for managing liquidity risk [line items]    
Trust pass-through securities 3 94
Subordinated loans 78 88
Borrowings 713 588
Investment contracts 104 9
Lease liabilities 28 30
Other financial liabilities 36 27
Later than two years and not later than three years [member] | Contractual maturities of each category of financial liabilities [member]    
Disclosure of maturity analysis for financial assets held for managing liquidity risk [line items]    
Trust pass-through securities 3 3
Subordinated loans 59 88
Borrowings 48 805
Investment contracts 21 118
Lease liabilities 26 27
Later than three years and not later than four years [member] | Contractual maturities of each category of financial liabilities [member]    
Disclosure of maturity analysis for financial assets held for managing liquidity risk [line items]    
Trust pass-through securities 3 3
Subordinated loans 40 67
Borrowings 48 51
Investment contracts 3 24
Lease liabilities 22 25
Other financial liabilities 0 4
Later than four years and not later than five years [member] | Contractual maturities of each category of financial liabilities [member]    
Disclosure of maturity analysis for financial assets held for managing liquidity risk [line items]    
Trust pass-through securities 3 3
Subordinated loans 40 46
Borrowings 48 51
Investment contracts 12 4
Lease liabilities 17 21
Later than 5 years [member] | Contractual maturities of each category of financial liabilities [member]    
Disclosure of maturity analysis for financial assets held for managing liquidity risk [line items]    
Trust pass-through securities 61 72
Subordinated loans 2,234 2,577
Borrowings 1,004 1,112
Investment contracts 41 60
Lease liabilities € 96 € 123