Individual Components of Work Force Reduction and Idle Lease Cost (Detail) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Dec. 31, 2015
Restructuring Cost and Reserve [Line Items]
Additional provisions	$ 26.9	$ 0.0	$ 118.5
Workforce Reductions | United States
Restructuring Cost and Reserve [Line Items]
Charges for work-force reductions	4.2	27.9	27.9
Additional provisions	4.5
Utilized	(3.1)		(23.7)
Changes in estimates and revisions	(0.3)
Balance at Dec. 31, 2015	5.3		4.2
Workforce Reductions | Non-US
Restructuring Cost and Reserve [Line Items]
Charges for work-force reductions	28.8	50.9	50.9
Additional provisions	18.5
Utilized	(8.9)		(21.6)
Changes in estimates and revisions	(0.6)
Translation adjustments	1.8		(0.5)
Balance at Dec. 31, 2015	39.6		28.8
Workforce Reductions | Remaining Of Current Year | United States
Restructuring Cost and Reserve [Line Items]
Expected future utilization	5.3
Workforce Reductions | Remaining Of Current Year | Non-US
Restructuring Cost and Reserve [Line Items]
Expected future utilization	37.9
Workforce Reductions | Beyond 2016 | Non-US
Restructuring Cost and Reserve [Line Items]
Expected future utilization	1.7
Other Restructuring
Restructuring Cost and Reserve [Line Items]
Charges for work-force reductions	33.0	$ 78.8	78.8
Additional provisions	23.0
Utilized	(12.0)		(45.3)
Changes in estimates and revisions	(0.9)
Translation adjustments	1.8		(0.5)
Balance at Dec. 31, 2015	44.9		$ 33.0
Other Restructuring | Remaining Of Current Year
Restructuring Cost and Reserve [Line Items]
Expected future utilization	43.2
Other Restructuring | Beyond 2016
Restructuring Cost and Reserve [Line Items]
Expected future utilization	$ 1.7