Debt - Summary Of Interest Expense (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Debt Instruments [Abstract]
Interest incurred	$ 173.8	$ 185.0	$ 206.1
Less: interest income	4.2	2.8	4.6
Less: interest capitalized as property, plant and equipment	1.3	2.6	2.8
Interest expense, net	$ 168.3	$ 179.6	$ 198.7