Restructuring - Costs Included in Selling, General & Administrative expenses on Consolidated Statements of Income (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 58.7	$ 24.5	$ 41.3
Severance and related costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs	57.1	24.5	34.5
Other
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 1.6	$ 0.0	$ 6.8