Other Noncurrent Liabilities - Other Noncurrent Liabilities (Detail) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Other Liabilities Disclosure [Abstract]
Accrued development costs	$ 38.7	$ 48.1
Accrued litigation settlement	27.7	27.4
Operating lease liabilities	$ 17.1	$ 17.4
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration]	Total	Total
Deferred income	$ 16.0	$ 25.9
Insurance claims and expenses	16.0	18.7
Other postretirement benefits	7.2	7.1
Employee benefits	4.9	4.8
Reserve for uncertain tax positions	0.3	0.3
Other	7.1	6.7
Total	$ 135.0	$ 156.4