Accumulated Other Comprehensive Income (Loss) - Schedule of Income Tax Allocated to Components of Other Comprehensive Income (Loss) (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Equity [Abstract]
Foreign currency translation adjustments	$ 1.9		$ 0.8
Unrecognized pension and postretirement costs	1.5	$ 1.2	4.2	$ 3.5
Derivative financial instruments	(1.1)	3.3	(7.7)	(28.6)
Income tax provision (benefit) related to OCI	$ 2.3	$ 4.5	$ (2.7)	$ (25.1)