Components of Net Pension (Income) Expense (Detail) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | ||
|---|---|---|---|---|
Sep. 30, 2026 |
Sep. 30, 2025 |
Sep. 30, 2026 |
Sep. 30, 2025 |
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| Defined Benefit Plan, Net Periodic Benefit Cost (Credit) [Abstract] | ||||
| Service cost | $ 22.4 | $ 24.0 | $ 67.4 | $ 71.4 |
| Interest on projected benefit obligation | 35.5 | 36.4 | 106.6 | 108.3 |
| Expected return on assets | $ (65.2) | $ (63.2) | $ (195.6) | $ (188.6) |
| 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 | $ 0.3 | $ 1.2 | $ 1.0 |
| Recognized actuarial loss | 1.0 | 0.6 | 3.0 | 1.4 |
| Net pension income | $ (5.9) | $ (1.9) | $ (17.4) | $ (6.5) |
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- Definition Amount of gain (loss) recognized in net periodic benefit (cost) credit of defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of prior service cost (credit) recognized in net periodic benefit cost (credit) of defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition 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. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of cost recognized for passage of time related to defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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- Definition Amount of net periodic benefit cost (credit) for defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- References No definition available.
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- Definition Indicates line item in statement of income or comprehensive income that includes components of net periodic benefit cost (credit), excluding service cost component, for defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition Amount of cost for actuarial present value of benefits attributed to service rendered by employee for defined benefit plan. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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