Retirement Plans, Postretirement and Postemployment Benefits - Schedule of Change In Plan Assets (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Defined Benefit Plan Disclosure [Line Items]
Balance at beginning of year	$ 1,067.1
Employer contributions	31.8	$ 90.2
Balance at end of year	1,176.8	1,067.1
Pension
Defined Benefit Plan Disclosure [Line Items]
Balance at beginning of year	1,067.1	1,200.3
Actual return on plan assets, net	123.1	(171.4)
Employer contributions	31.8	90.2
Gross benefits paid	(45.2)	(52.0)
Balance at end of year	1,176.8	1,067.1
Postretirement Benefits
Defined Benefit Plan Disclosure [Line Items]
Balance at beginning of year	0.0	0.0
Employer contributions	1.0	1.0
Participants' contributions	0.7	0.6
Gross benefits paid	(1.7)	(1.6)
Balance at end of year	$ 0.0	$ 0.0