Schedule of Changes in Balance Sheet Position of Restructuring Reserves (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Restructuring Cost And Reserve [Line Items]
Restructuring reserve, beginning balance	$ 37.5	$ 87.9	$ 79.8
Provision/ Charge	34.0	26.7	82.8
Provision/ Reversal	(7.4)	(2.8)	(2.9)
Cash payments	(27.1)	(73.0)	(63.6)
Translation difference	4.7	(1.3)	(8.2)
Restructuring reserve, ending balance	41.7	37.5	87.9
Restructuring employee-related
Restructuring Cost And Reserve [Line Items]
Restructuring reserve, beginning balance	37.1	87.7	79.6
Provision/ Charge	33.7	26.2	82.6
Provision/ Reversal	(7.0)	(2.8)	(2.9)
Cash payments	(27.1)	(73.0)	(63.4)
Translation difference	4.7	(1.0)	(8.2)
Restructuring reserve, ending balance	41.4	37.1	87.7
Other Restructuring
Restructuring Cost And Reserve [Line Items]
Restructuring reserve, beginning balance	0.4	0.2	0.2
Provision/ Charge	0.3	0.5	0.2
Provision/ Reversal	(0.4)
Cash payments			(0.2)
Translation difference	0.0	(0.3)	0.0
Restructuring reserve, ending balance	$ 0.3	$ 0.4	$ 0.2