Income Taxes - Schedule of Transactions Affecting Valuation Allowance on Deferred Tax Assets (Detail) - Valuation Allowance of Deferred Tax Assets - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Valuation Allowance [Line Items]
Balance, beginning of year	$ 154.1	$ 130.8	$ 144.3
Current year expense-net	84.5	35.2	11.8
Write-offs	(6.8)	(1.0)	(15.0)
Foreign exchange and other	6.5	(10.9)	(10.3)
Balance, end of year	$ 238.3	$ 154.1	$ 130.8