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