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Retirement Plans, Postretirement and Postemployment Benefits - Schedule of Fair Values of Pension Plan Assets by Asset Class and Fair Value Hierarchy Level (Detail) - USD ($) $ in Millions | Dec. 31, 2023 | Dec. 31, 2022
--- | --- | ---
Defined Benefit Plan Disclosure [Line Items] |  |
Fair values of pension plan assets | $ 1,176.8 | $ 1,067.1
Quoted Prices In Active Markets For Identical Assets (Level 1) |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair values of pension plan assets | 0.0 | 0.2
Net Asset Value |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair values of pension plan assets | 1,176.8 | 1,066.9
Mid-sized to Large Cap |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair values of pension plan assets | 307.2 | 291.6
Mid-sized to Large Cap | Net Asset Value |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair values of pension plan assets | 307.2 | 291.6
Small Cap, International and Emerging Growth Funds |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair values of pension plan assets | 319.5 | 287.2
Small Cap, International and Emerging Growth Funds | Net Asset Value |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair values of pension plan assets | 319.5 | 287.2
Debt Securities |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair values of pension plan assets | 319.2 | 249.1
Debt Securities | Net Asset Value |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair values of pension plan assets | 319.2 | 249.1
Real Estate |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair values of pension plan assets | 136.7 | 151.5
Real Estate | Net Asset Value |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair values of pension plan assets | 136.7 | 151.5
Private infrastructure |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair values of pension plan assets | 90.2 | 83.1
Private infrastructure | Net Asset Value |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair values of pension plan assets | 90.2 | 83.1
Cash Equivalents |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair values of pension plan assets | 4.0 | 4.6
Cash Equivalents | Quoted Prices In Active Markets For Identical Assets (Level 1) |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair values of pension plan assets | 0.0 | 0.2
Cash Equivalents | Net Asset Value |  |
Defined Benefit Plan Disclosure [Line Items] |  |
Fair values of pension plan assets | $ 4.0 | $ 4.4

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