Cost-Reduction Actions - Liabilities and Expected Future Payments Related to Work-Force Reduction Actions (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2020
Restructuring Reserve [Roll Forward]
Additional provisions	$ 13.2	$ 0.2	$ 48.6	$ 5.4
Work-force Reductions
Restructuring Reserve [Roll Forward]
Balance at beginning of period			49.8
Additional provisions			14.0
Payments			(17.7)
Changes in estimates			(7.8)
Translation adjustments			0.7
Balance at end of period	39.0		39.0
2020 remaining three months	9.1		9.1
Beyond 2020	9.1		9.1
Work-force Reductions | Forecast
Restructuring Reserve [Roll Forward]
2020 remaining three months					$ 29.9
Beyond 2020					29.9
Work-force Reductions | U.S.
Restructuring Reserve [Roll Forward]
Balance at beginning of period			5.2
Additional provisions			4.0
Payments			(2.3)
Changes in estimates			0.0
Translation adjustments			0.0
Balance at end of period	6.9		6.9
2020 remaining three months	5.6		5.6
Beyond 2020	5.6		5.6
Work-force Reductions | U.S. | Forecast
Restructuring Reserve [Roll Forward]
2020 remaining three months					1.3
Beyond 2020					1.3
Work-force Reductions | International
Restructuring Reserve [Roll Forward]
Balance at beginning of period			44.6
Additional provisions			10.0
Payments			(15.4)
Changes in estimates			(7.8)
Translation adjustments			0.7
Balance at end of period	32.1		32.1
2020 remaining three months	3.5		3.5
Beyond 2020	$ 3.5		$ 3.5
Work-force Reductions | International | Forecast
Restructuring Reserve [Roll Forward]
2020 remaining three months					28.6
Beyond 2020					$ 28.6