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, 2024	Dec. 31, 2023	Dec. 31, 2022
Change in PBO:
Actuarial losses/(gains)		$ 21.3	$ 17.5	$ 69.9
Fair value of plan assets:
Opening balance		35.1
Closing balance		2.4	35.1
United Kingdom Plan [Member]
Fair value of plan assets:
Opening balance		459.2	452.1
Return of Funds to Cover Historic Expenses	$ 8.4	(8.4)	0.0
Benefits paid		(32.9)	(35.6)
Actual return on assets		1.5	17.9
Settlements		(419.2)	0.0
Exchange effect		2.3	24.8
Closing balance		2.5	459.2	452.1
German Plan [Member]
Change in PBO:
Opening balance		9.1	8.2
Interest cost		0.3	0.3	0.1
Service cost/(credit)		0.0	0.1	0.1
Benefits paid		(0.4)	(0.3)
Actuarial losses/(gains)		0.5	0.6
Exchange effect		(0.5)	0.2
Closing balance		9.0	9.1	8.2
Pension Benefit Obligation [Member] \| United Kingdom Plan [Member]
Change in PBO:
Opening balance		424.1	404.0
Interest cost		18.6	19.6
Service cost/(credit)		(4.9)	3.5
Benefits paid		(32.9)	(35.6)
Plan amendments		8.4	0.0
Actuarial losses/(gains)		3.7	10.1
Settlements		(419.2)	0.0
Exchange effect		2.3	22.5
Closing balance		$ 0.1	$ 424.1	$ 404.0

Defined benefit plan , Return of funds to cover historic expenses.

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- Definition

Defined Benefit Plan Service Credit Cost

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No definition available.

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- Definition

Amount of increase (decrease) in plan assets of defined benefit plan from actual return (loss) determined by change in fair value of plan assets adjusted for contributions, benefit payments, and other expenses.

+ References

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- Definition

Amount of gain (loss) from change in actuarial assumptions which (increases) decreases benefit obligation of defined benefit plan. Assumptions include, but are not limited to, interest, mortality, employee turnover, salary, and temporary deviation from substantive plan.

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- Definition

Amount of asset, recognized in statement of financial position, for overfunded defined benefit pension and other postretirement plans.

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- Definition

Amount of actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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- Definition

Amount of payment to participant of defined benefit plan which decreases benefit obligation. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

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- Definition

Amount of payment, which decreases benefit obligation of defined benefit plan, for irrevocable action relieving primary responsibility for benefit obligation and eliminating risk for obligation and assets used to effect settlement. Transaction constituting settlement includes, but is not limited to, making lump-sum cash payment to participant in exchange for their rights to receive specified benefits and purchasing nonparticipating annuity contract. Excludes decreases to benefit obligation for remeasurement due to settlement.

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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No definition available.

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A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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- Definition

Amount of foreign currency translation gain (loss) which (increases) decreases benefit obligation of defined benefit plan.

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- Definition

Amount of cost recognized for passage of time related to defined benefit plan.

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- Definition

Amount of increase (decrease) in benefit obligation of defined benefit plan from change in terms of existing plan or initiation of new plan.

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Amount of payment to participant under defined benefit plan which decreases plan assets. For pension plan, payment includes, but is not limited to, pension benefits and death benefits. For other postretirement plan, payment includes, but is not limited to, prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

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- Definition

Amount of foreign currency translation gain (loss) which increases (decreases) plan assets of defined benefit plan.

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- Definition

Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan.

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Amount of payment, which decreases plan assets of defined benefit plan, for irrevocable action relieving primary responsibility for benefit obligation and eliminating risk for obligation and assets used to effect settlement. Transaction constituting settlement includes, but is not limited to, making lump-sum cash payment to participant in exchange for their rights to receive specified benefits and purchasing nonparticipating annuity contract.

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