Restructuring - Restructuring Related Costs Included in Selling, General & Administrative expenses on Consolidated Statements of Income (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 25.0	$ 5.9	$ 30.6	$ 17.5
Severance and related costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs	4.6	5.9	10.0	17.4
Other
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 20.4	$ 0.0	$ 20.6	$ 0.1