v3.26.1

Components of Net Pension (Income) Expense (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2026	Jun. 30, 2025	Jun. 30, 2026	Jun. 30, 2025
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract]
Service cost	$ 22.6	$ 23.2	$ 45.0	$ 47.4
Interest on projected benefit obligation	35.5	36.1	71.1	71.9
Expected return on assets	$ (65.0)	$ (63.1)	$ (130.4)	$ (125.4)
Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Excluding Service Cost, Statement of Income or Comprehensive Income [Extensible Enumeration]	Costs and Expenses	Costs and Expenses	Costs and Expenses	Costs and Expenses
Amortization of prior service costs	$ 0.4	$ 0.4	$ 0.8	$ 0.7
Recognized actuarial loss	0.9	0.1	2.0	0.8
Net pension income	$ (5.6)	$ (3.3)	$ (11.5)	$ (4.6)

Amount of gain (loss) recognized in net periodic benefit (cost) credit of defined benefit plan.

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Amount of prior service cost (credit) recognized in net periodic benefit cost (credit) of defined benefit plan.

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Amount of expected return (loss) recognized in net periodic benefit (cost) credit, calculated based on expected long-term rate of return and market-related value of plan assets of defined benefit plan.

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

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Amount of net periodic benefit cost (credit) for defined benefit plan.

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

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