Benefit Plans - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Retirement Benefits [Abstract]
Service cost	$ 0.4	$ 0.6	$ 1.2	$ 1.8
Interest cost	1.0	0.6	3.0	1.8
Expected return on plan assets	(0.2)	(0.1)	(0.6)	(0.3)
Net periodic benefit cost	$ 1.2	$ 1.1	$ 3.6	$ 3.3