Valuation Allowance Against Deferred Tax Assets (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Allowances at beginning of year	$ 110.6	$ 199.6	$ 177.7
Benefits reserved current year	6.4	22.9	32.3
Benefits recognized current year	(36.9)	(117.0)	(13.8)
Write-offs and other changes		(0.1)	(0.5)
Translation difference	(9.1)	5.2	3.9
Allowances at end of year	$ 71.0	$ 110.6	$ 199.6