Plant Closure Provisions - Movements in Plant Closure and Restructuring Provisions (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Restructuring Cost and Reserve [Line Items]
Beginning Balance	$ 34.1	$ 32.4	$ 30.4
Charge for the period	6.8	5.0	3.9
Utilized in the period	(2.6)	(2.0)	(2.0)
Disposal in the period	(0.3)
Released in the period		(1.0)
Exchange effect	(0.3)	(0.3)	0.1
Ending Balance	37.7	34.1	32.4
Due within one year				$ (6.4)	$ (5.7)	$ (6.2)
Due after one year				31.3	28.4	26.2
Ending Balance	34.1	32.4	30.4	37.7	34.1	32.4
Severance [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	0.0	1.0	1.1
Charge for the period	0.0	0.0	0.0
Utilized in the period	0.0	0.0	(0.1)
Disposal in the period	0.0
Released in the period		(1.0)
Exchange effect	0.0	0.0	0.0
Ending Balance	0.0	0.0	1.0
Due within one year				0.0	0.0	0.0
Due after one year				0.0	0.0	1.0
Ending Balance	0.0	1.0	1.1	0.0	0.0	1.0
Remediation [Member]
Restructuring Cost and Reserve [Line Items]
Beginning Balance	34.1	31.4	29.3
Charge for the period	6.8	5.0	3.9
Utilized in the period	(2.6)	(2.0)	(1.9)
Disposal in the period	(0.3)
Released in the period		0.0
Exchange effect	(0.3)	(0.3)	0.1
Ending Balance	37.7	34.1	31.4
Due within one year				(6.4)	(5.7)	(6.2)
Due after one year				31.3	28.4	25.2
Ending Balance	$ 34.1	$ 31.4	$ 29.3	$ 37.7	$ 34.1	$ 31.4

Restructuring charges disposal in period

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- Definition

Amount charged against earnings in the period for incurred and estimated costs associated with exit from or disposal of business activities or restructurings pursuant to a duly authorized plan, including asset retirement obligations.

+ References

No definition available.

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- Definition

Amount of cash payments made as the result of exit or disposal activities. Excludes payments associated with a discontinued operation or an asset retirement obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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Carrying amount (including both current and noncurrent portions of the accrual) as of the balance sheet date pertaining to a specified type of cost associated with exit from or disposal of business activities or restructuring pursuant to a duly authorized plan.

+ References

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- Definition

Carrying amount as of the balance sheet date of known and estimated obligations associated with exit from or disposal of business activities or restructurings pursuant to a duly authorized plan, which are expected to be paid in the next twelve months or in the normal operating cycle if longer. Costs of such activities include those for one-time termination benefits, termination of an operating lease or other contract, consolidating or closing facilities, relocating employees, and costs associated with an ongoing benefit arrangement, but excludes costs associated with the retirement of a long-lived asset.

+ References

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Carrying amount as of the balance sheet date of known and estimated costs associated with exit from or disposal of business activities or restructurings pursuant to a duly authorized plan, which are expected to be paid after one year or beyond the next operating cycle, if longer. Costs of such activities include those for one-time termination benefits, termination of an operating lease or other contract, consolidating or closing facilities, and relocating employees, and costs associated with an ongoing benefit arrangement, but excludes costs associated with the retirement of a long-lived asset.

+ References

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- Definition

Amount of consideration other than cash used to fully or partially settle an accrued restructuring cost.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 5.P.4(b)(2))
-URI http://asc.fasb.org/extlink&oid=27011515&loc=d3e140904-122747

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 5
-Section P
-Subsection 3, 4

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- Definition

Amount of gain (loss) from translating a restructuring reserve to the currency of the reporting entity from an amount denominated or measured in a different currency.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB TOPIC 5.P.4(b)(2))
-URI http://asc.fasb.org/extlink&oid=27011515&loc=d3e140904-122747

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 420
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (b)(2)
-URI http://asc.fasb.org/extlink&oid=6394359&loc=d3e17939-110869

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Staff Accounting Bulletin (SAB)
-Number Topic 5
-Section P
-Subsection 3, 4

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