Restructuring - Costs Included in Selling, General & Administrative expenses on Consolidated Statements of Income (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 40.6	$ 28.2	$ 12.2
Severance and related costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs	13.2	27.3	12.2
Other
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 27.4	$ 0.9	$ 0.0