Schedule of Changes in Balance Sheet Position of Restructuring Reserves (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Restructuring Cost and Reserve [Line Items]
Restructuring reserve, beginning balance	$ 56.1	$ 33.4	$ 39.6
Provision/ Charge	108.8	56.9	9.2
Provision/ Reversal	(10.1)	(3.0)	(0.1)
Cash payments	(38.4)	(30.3)	(13.6)
Translation difference	9.5	(0.9)	(1.7)
Restructuring reserve, ending balance	125.9	56.1	33.4
Restructuring employee-related
Restructuring Cost and Reserve [Line Items]
Restructuring reserve, beginning balance	55.9	33.2	39.4
Provision/ Charge	108.5	56.9	9.0
Provision/ Reversal	(10.1)	(3.0)	(0.1)
Cash payments	(38.4)	(30.3)	(13.6)
Translation difference	9.5	(0.9)	(1.5)
Restructuring reserve, ending balance	125.4	55.9	33.2
Other Restructuring
Restructuring Cost and Reserve [Line Items]
Restructuring reserve, beginning balance	0.2	0.2	0.2
Provision/ Charge	0.3		0.2
Translation difference	0.0	0.0	(0.2)
Restructuring reserve, ending balance	$ 0.5	$ 0.2	$ 0.2