Restructuring - Costs Included in Selling, General & Administrative Expenses (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 2.9	$ 3.5	$ 10.7	$ 34.1
Severance and related costs
Restructuring Cost and Reserve [Line Items]
Restructuring costs	2.1	2.8	9.6	12.8
Other
Restructuring Cost and Reserve [Line Items]
Restructuring costs	$ 0.8	$ 0.7	$ 1.1	$ 21.3