Retirement Plans, Postretirement and Postemployment Benefits - Net Periodic Benefit Cost Recognized Pretax Amounts in Comprehensive Earnings (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension
Defined Benefit Plan Disclosure [Line Items]
Actuarial loss (gain)	$ 20.9	$ (114.5)	$ (67.5)
Prior service cost	0.0	48.1	0.0
Prior service cost	(5.9)	(4.9)	(0.8)
Actuarial gain (loss)	(0.6)	(3.9)	(12.2)
Settlement charge	0.0	(4.6)	0.0
Total	14.4	(79.8)	(80.5)
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Actuarial loss (gain)	(0.1)	(2.0)	(0.6)
Prior service cost	0.3	0.9	0.8
Actuarial gain (loss)	0.6	0.2	0.1
Total	$ 0.8	$ (0.9)	$ 0.3