Other Noncurrent Liabilities - Other Noncurrent Liabilities (Detail) - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Other Liabilities Disclosure [Abstract]
Reserve for uncertain tax positions	$ 17.5	$ 16.5
Litigation settlement	17.0
Deferred income	15.0	15.7
Employee benefits	8.1	8.4
Insurance claims and expenses	9.9	9.1
Deferred payment obligation	9.5	9.3
Accrued development costs	8.8	6.1
Other	9.1	8.5
Total	$ 94.9	$ 73.6