Benefit Plans - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Retirement Benefits [Abstract]
Service cost	$ 0.4	$ 0.4	$ 1.2	$ 1.2
Interest cost	1.0	1.0	3.0	3.0
Expected return on plan assets	(0.1)	(0.2)	(0.3)	(0.6)
Net periodic benefit cost	$ 1.3	$ 1.2	$ 3.9	$ 3.6