Defined Benefit Plans - Summary of Expected Guaranteed Premiums and Management Fees Net Defined Benefit Liability Asset (Detail) - EUR (€) € in Millions |
12 Months Ended | |
|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
|
| Disclosure of net defined benefit liability (asset) [line items] | ||
| Beginning Balance | € 9 | |
| Remeasurements of the defined benefit obligations: | ||
| End Balance | 28 | € 9 |
| Aegon Ltd. [member] | ||
| Disclosure of net defined benefit liability (asset) [line items] | ||
| Beginning Balance | 5 | |
| Remeasurements of the defined benefit obligations: | ||
| Transfer from AEN | 53 | |
| End Balance | 16 | 5 |
| Aegon Ltd. [member] | Present value of the expected guaranteed premiums and management fees [member] | ||
| Disclosure of net defined benefit liability (asset) [line items] | ||
| Beginning Balance | 44 | |
| Remeasurements of the defined benefit obligations: | ||
| - Actuarial gains and losses arising from changes in financial assumptions | (9) | 5 |
| Benefits paid | (2) | (1) |
| Transfer from AEN | 40 | |
| End Balance | € 33 | € 44 |