Benefit Plans - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Retirement Benefits [Abstract]
Service cost	$ 0.4	$ 0.4	$ 0.8	$ 0.8
Interest cost	1.0	1.0	2.0	2.0
Expected return on plan assets	(0.1)	(0.2)	(0.2)	(0.4)
Net periodic benefit cost	$ 1.3	$ 1.2	$ 2.6	$ 2.4