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Cost-Reduction Actions - Individual Components of Work Force Reduction and Idle Lease Cost (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2018	Dec. 31, 2018
Restructuring Reserve [Roll Forward]
Changes in estimates	$ (0.9)	$ (3.1)
Total
Restructuring Reserve [Roll Forward]
Balance at beginning of period		117.8
Payments		(34.6)
Changes in estimates		(2.9)
Translation adjustments		(2.9)
Balance at end of period	77.4	77.4
2018 remaining three months	12.5	12.5
Beyond 2018	12.5	12.5
Total \| Forecast
Restructuring Reserve [Roll Forward]
2018 remaining three months			$ 64.9
Beyond 2018			64.9
Work-Force Reductions \| U.S.
Restructuring Reserve [Roll Forward]
Balance at beginning of period		3.9
Payments		(2.8)
Changes in estimates		(1.0)
Translation adjustments		0.0
Balance at end of period	0.1	0.1
2018 remaining three months	0.1	0.1
Beyond 2018	0.1	0.1
Work-Force Reductions \| U.S. \| Forecast
Restructuring Reserve [Roll Forward]
2018 remaining three months			0.0
Beyond 2018			0.0
Work-Force Reductions \| International
Restructuring Reserve [Roll Forward]
Balance at beginning of period		109.6
Payments		(30.2)
Changes in estimates		(2.5)
Translation adjustments		(2.8)
Balance at end of period	74.1	74.1
2018 remaining three months	12.0	12.0
Beyond 2018	12.0	12.0
Work-Force Reductions \| International \| Forecast
Restructuring Reserve [Roll Forward]
2018 remaining three months			62.1
Beyond 2018			62.1
Idle Leased Facilities Costs
Restructuring Reserve [Roll Forward]
Balance at beginning of period		4.3
Payments		(1.6)
Changes in estimates		0.6
Translation adjustments		(0.1)
Balance at end of period	3.2	3.2
2018 remaining three months	0.4	0.4
Beyond 2018	$ 0.4	$ 0.4
Idle Leased Facilities Costs \| Forecast
Restructuring Reserve [Roll Forward]
2018 remaining three months			2.8
Beyond 2018			$ 2.8