Retirement Plans, Postretirement and Postemployment Benefits - Net Periodic Benefit Credit or Cost Not Yet Recognized (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Pension
Defined Benefit Plan Disclosure [Line Items]
Prior service cost (credit) - Gross	$ 48.2	$ 5.1
Actuarial (gain) loss - Gross	43.2	166.2
Total - Gross	91.4	171.3
Prior service cost (credit) - Net of tax	20.3	3.0
Actuarial (gain) loss - Net of tax	18.2	97.0
Total - Net of tax	38.5	100.0
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Prior service cost (credit) - Gross	(0.7)	(1.5)
Actuarial (gain) loss - Gross	(4.1)	(2.4)
Total - Gross	(4.8)	(3.9)
Prior service cost (credit) - Net of tax	(0.3)	(0.9)
Actuarial (gain) loss - Net of tax	(1.7)	(1.4)
Total - Net of tax	$ (2.0)	$ (2.3)