Other Equity Instruments - Summary of Coupon Details - Junior Perpetual Capital Securities (Detail) - EUR (€) € in Millions |
12 Months Ended | ||
|---|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
Dec. 31, 2023 |
|
| Disclosure of other equity instruments [line items] | |||
| Borrowings | € 1,982 | € 3,013 | |
| Junior perpetual capital securities [member] | |||
| Disclosure of other equity instruments [line items] | |||
| Borrowings | € 923 | 923 | € 923 |
| Junior perpetual capital securities [member] | USD 500 million [member] | |||
| Disclosure of other equity instruments [line items] | |||
| Borrowings currency | USD | ||
| Coupon rate | floating CMS rate | ||
| Coupon date, as of | Quarterly, July 15 | ||
| Year of next call | 2026 | ||
| Borrowings | € 402 | 402 | 402 |
| Junior perpetual capital securities [member] | EUR 950 million [member] | |||
| Disclosure of other equity instruments [line items] | |||
| Borrowings currency | EUR | ||
| Coupon rate | floating DSL rate | ||
| Coupon date, as of | Quarterly, July 15 | ||
| Year of next call | 2026 | ||
| Borrowings | € 521 | € 521 | € 521 |