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v3.25.4

Pension and Post-Employment Benefits - Movements in PBO and Fair Value of Plan Assets (Detail) - USD ($) $ in Millions | 1 Months Ended | 12 Months Ended
--- | --- | ---
Sep. 30, 2024 | Dec. 31, 2025 | Dec. 31, 2024 | Dec. 31, 2023
Fair value of plan assets: |  |  |  |
Opening balance |  | $ 2.4 |  |
Closing balance |  | 0.0 | $ 2.4 |
United Kingdom Plan [Member] |  |  |  |
Fair value of plan assets: |  |  |  |
Opening balance |  | 2.5 | 459.2 |
Return of funds to cover historic expenses | $ 8.4 | (0.9) | (8.4) |
Scheme closure expenses |  | (1.6) | 0.0 |
Benefits paid |  | 0.0 | (32.9) |
Actual return on assets |  | 0.0 | 1.5 |
Settlements |  | 0.0 | (419.2) |
Exchange effect |  | 0.0 | 2.3 |
Closing balance |  | 0.0 | 2.5 | $ 459.2
German Plan [Member] |  |  |  |
Change in PBO: |  |  |  |
Opening balance |  | 9.0 | 9.1 |
Interest cost |  | 0.3 | 0.3 | 0.3
Service cost/(credit) |  | 0.0 | 0.0 | 0.1
Benefits paid |  | (0.5) | (0.4) |
Actuarial losses/(gains) |  | (0.6) | 0.5 |
Exchange effect |  | 1.2 | (0.5) |
Closing balance |  | 9.4 | 9.0 | 9.1
Pension Benefit Obligation [Member] | United Kingdom Plan [Member] |  |  |  |
Change in PBO: |  |  |  |
Opening balance |  | 0.1 | 424.1 |
Interest cost |  | 0.0 | 18.6 |
Service cost/(credit) |  | 1.5 | (4.9) |
Benefits paid |  | 0.0 | (32.9) |
Plan amendments |  | 0.0 | 8.4 |
Scheme closure expenses |  | (1.6) | 0.0 |
Actuarial losses/(gains) |  | 0.0 | 3.7 |
Settlements |  | 0.0 | (419.2) |
Exchange effect |  | 0.0 | 2.3 |
Closing balance |  | $ 0.0 | $ 0.1 | $ 424.1

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