Fair Value - Additional Information (Detail) - EUR (€) € in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
|
| Credit spread [member] | Weighted average [member] | Corporate bonds [member] | ||
| Disclosure of fair value measurement of assets and liabilities [line items] | ||
| Interest rate | 0.00% | |
| Tax credit investments [member] | ||
| Disclosure of fair value measurement of assets and liabilities [line items] | ||
| Discount rate used in valuation of tax credit investments | 6.70% | 6.70% |
| Net asset value [member] | Recurring fair value measurement [member] | Federal Home Loan Bank shares [member] | ||
| Disclosure of fair value measurement of assets and liabilities [line items] | ||
| At fair value through other comprehensive income | € 36 | € 77 |