Plant Closures and Discontinued Operations - Summary of Restructuring Activities and Related Reserves (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Restructuring Cost And Reserve [Line Items]
Reserve, Beginning Balance	$ 18.3	$ 16.1
Accrual	4.9	14.6
Costs charged against assets	(2.1)	(6.3)
Reversal of accrued charges	(0.9)	(2.1)
Cash paid	(11.8)	(4.8)
Currency translation	(0.3)	0.8
Reserve, Ending Balance	8.1	18.3
Severance and Employee Benefits [Member]
Restructuring Cost And Reserve [Line Items]
Reserve, Beginning Balance	1.7	1.4
Accrual	0.0	0.9
Costs charged against assets	0.0	0.0
Reversal of accrued charges	0.0	(0.3)
Cash paid	0.0	(0.3)
Currency translation	0.0	0.0
Reserve, Ending Balance	1.7	1.7
Environmental Remediation [Member]
Restructuring Cost And Reserve [Line Items]
Reserve, Beginning Balance	2.7	1.5
Accrual	0.9	2.1
Costs charged against assets	0.0	0.0
Reversal of accrued charges	0.0	0.0
Cash paid	(3.4)	(1.1)
Currency translation	(0.2)	0.2
Reserve, Ending Balance	0.0	2.7
Asset Retirement [Member]
Restructuring Cost And Reserve [Line Items]
Reserve, Beginning Balance	10.6	10.0
Accrual	1.8	4.7
Costs charged against assets	0.0	0.0
Reversal of accrued charges	(0.9)	(1.8)
Cash paid	(7.9)	(2.4)
Currency translation	0.0	0.1
Reserve, Ending Balance	3.6	10.6
Other [Member]
Restructuring Cost And Reserve [Line Items]
Reserve, Beginning Balance	3.3	3.2
Accrual	2.2	6.9
Costs charged against assets	(2.1)	(6.3)
Reversal of accrued charges	0.0	0.0
Cash paid	(0.5)	(1.0)
Currency translation	(0.1)	0.5
Reserve, Ending Balance	$ 2.8	$ 3.3