Investments in Joint Ventures and Associates - Additional information (Detail) - EUR (€) € in Millions |
Dec. 31, 2025 |
Dec. 31, 2024 |
|---|---|---|
| Disclosure of joint ventures [Line Items] | ||
| Fair value of investment in quoted share held by the company | € 2,992 | € 2,864 |
| Spot rate of discounting liabilities cash flow | 4.50% | 4.20% |
| Percentage of stake | 24.12% | |
| 20 year [member] | ||
| Disclosure of joint ventures [Line Items] | ||
| Basis points | 0.30% | 0.30% |
| 20 year thereafter [member] | ||
| Disclosure of joint ventures [Line Items] | ||
| Basis points | 0.20% | 0.20% |
| Bottom of range [member] | ||
| Disclosure of joint ventures [Line Items] | ||
| Percentage of stake | 24.12% | |
| Top of range [member] | ||
| Disclosure of joint ventures [Line Items] | ||
| Percentage of stake | 29.96% |