Other Noncurrent Liabilities - Other Noncurrent Liabilities (Detail) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Other Liabilities Disclosure [Abstract]
Operating lease liability	$ 25.6
Reserve for uncertain tax positions	19.4	$ 19.1
Accrued litigation settlement	17.0	17.0
Deferred income	7.7	15.8
Other postretirement benefits	10.3	10.3
Employee benefits	6.9	7.1
Insurance claims and expenses	9.0	8.1
Deferred payment obligation	9.7	9.6
Accrued development costs	8.2	7.5
Other	9.6	9.9
Total	$ 123.4	$ 104.4