Benefit Plans - Obligations and Funded Status (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Change in benefit obligations
Service cost	$ 1.7	$ 2.4	$ 2.8
Interest cost	4.1	2.5	2.0
Change in plan assets
Fair value of plan assets beginning of year	28.4
Fair value of plan assets end of year	30.5	28.4
Pension plans
Change in benefit obligations
Benefit obligation beginning of year	90.5	116.1
Service cost	1.7	2.4
Interest cost	4.1	2.5
Actuarial loss	7.4	(22.6)
Translation (gain) loss	1.1	(0.2)
Benefits paid	(7.3)	(7.7)
Benefit obligation end of year	97.5	90.5	116.1
Change in plan assets
Fair value of plan assets beginning of year	28.4	34.4
Actual return on plan assets	0.8	(5.8)
Company contributions	7.6	7.5
Translation gain (loss)	1.0	0.0
Benefits paid	(7.3)	(7.7)
Fair value of plan assets end of year	30.5	28.4	34.4
Funded status
Plan assets less than benefit obligation	(67.0)	(62.1)
Other post-retirement plans
Change in benefit obligations
Benefit obligation beginning of year	9.0	11.3
Service cost	0.0	0.0
Interest cost	0.5	0.3
Actuarial loss	(0.8)	(1.3)
Translation (gain) loss	0.0	0.0
Benefits paid	(1.1)	(1.3)
Benefit obligation end of year	7.6	9.0	11.3
Change in plan assets
Fair value of plan assets beginning of year	0.0	0.0
Actual return on plan assets	0.0	0.0
Company contributions	1.1	1.3
Translation gain (loss)	0.0	0.0
Benefits paid	(1.1)	(1.3)
Fair value of plan assets end of year	0.0	0.0	$ 0.0
Funded status
Plan assets less than benefit obligation	$ (7.6)	$ (9.0)