Other Comprehensive Loss - Schedule of Reclassification From Accumulated Other Comprehensive Loss (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassification, net of tax	$ (0.2)	$ 1.9	$ (4.9)	$ 3.1
Other operating expense (income)	2.3		(2.1)	(0.1)
Investment and other income-net	2.2	3.6	6.7	9.2
Translation Adjustments
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassification, net of tax			(4.5)
Translation Adjustments | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Other operating expense (income)			(4.5)
Net Actuarial Loss | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Investment and other income-net	0.7	1.9	2.2	3.9
Net Prior Service Credit | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Investment and other income-net	(0.9)	(0.7)	(2.7)	(1.4)
Settlements | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Investment and other income-net		1.0		1.3
Amortization of Pension and OPEB Cost
Reclassification Adjustment Out Of Accumulated Other Comprehensive Income [Line Items]
Reclassifications before tax	(0.2)	2.2	(0.5)	3.8
Income tax (benefit) expense		0.3	(0.1)	0.7
Reclassification, net of tax	$ (0.2)	$ 1.9	$ (0.4)	$ 3.1