Property, Plant and Equipment - Narrative (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Property Plant And Equipment [Abstract]
Depreciation expense	$ 32.3	$ 34.9	$ 65.6	$ 70.6
Building and related land sales, deposit received	$ 32.1		32.1		$ 12.5
Gross proceeds including deposits from the sale to be expected			$ 250.0