Defined Benefit Pension Plans - Components of Net Periodic Defined Benefit Pension Benefit Cost (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Compensation And Retirement Disclosure [Abstract]
Service cost	$ 1.6	$ 2.8	$ 4.7	$ 8.7
Interest cost	5.5	3.0	16.6	9.2
Expected return on plan assets	(5.1)	(3.5)	(15.5)	(10.4)
Recognized net actuarial losses	1.0	3.6	2.9	11.1
Settlements	0.0	0.0	6.2	0.0
Total	$ 3.0	$ 5.9	$ 14.9	$ 18.6