Retirement Plans - Components of Estimated Net Periodic Benefit Income (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 1.9	$ 1.5	$ 3.7	$ 3.1
Expected return on assets	(3.0)	(3.6)	(5.8)	(7.1)
Amortization, net	0.8	1.0	1.6	1.9
Net pension plan income	$ (0.3)	$ (1.1)	$ (0.5)	$ (2.1)