Amounts Recognized In Accumulated Other Comprehensive Loss (Detail) - Pension Plans, Defined Benefit - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Defined Benefit Plan Disclosure [Line Items]
Net loss	$ 169.2	$ 163.7
Prior service credit	(1.9)	(2.7)
Before tax amount	167.3	161.0
After tax amount	$ 108.7	$ 103.8