Commitments and Contingencies - Rollforward of Environmental Liability and Related Assets (Detail) - Liability [Member] - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2018	Dec. 31, 2017
Environmental Liability and Related Assets [Roll Forward]
Changes in estimates for pre-existing accruals(a)	[1]	$ 6.6	$ 8.8
Environmental Related Matters [Member]
Environmental Liability and Related Assets [Roll Forward]
Balance as of January 1		73.9	76.6
Accruals added during the period for new matters		2.0
Net cash activity(b)	[2]	(15.8)	(11.7)
Foreign currency		0.1	0.2
Balance as of December 31		$ 66.8	$ 73.9

[1] (a)Changes in estimates for pre-existing accruals includes environmental-related costs $3.7 reported within results of discontinued operations for the year ended December 31, 2017.

[2] (b)Includes cash payments the year ended December 31, 2018 and 2017 of $10.2 and $4.6, respectively, related to the sale of a former operating location.