Benefit Plans - Components of Net Periodic Benefit Cost (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Retirement Benefits [Abstract]
Service cost	$ 0.6	$ 0.7	$ 1.8	$ 2.1
Interest cost	0.6	0.5	1.8	1.5
Expected return on plan assets	(0.1)	(0.1)	(0.3)	(0.3)
Net periodic benefit cost	$ 1.1	$ 1.1	$ 3.3	$ 3.3