Provisions - Movement in Provisions (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Reconciliation of changes in other provisions [abstract]
Provisions, beginning balance	$ 2.6	$ 5.3
Charged to consolidated income statement	5.2	1.4
Credited to consolidated income statement	(0.4)	(0.6)
Cash payments	(3.5)	(3.3)
Translation		(0.2)
Provisions, ending balance	3.9	2.6
Included in current liabilities	2.8	1.5
Included in non-current liabilities	1.1	1.1
Rationalization and redundancy
Reconciliation of changes in other provisions [abstract]
Provisions, beginning balance	0.8	2.6
Charged to consolidated income statement	4.3	1.4
Credited to consolidated income statement	0.0	(0.2)
Cash payments	(3.0)	(3.0)
Translation		0.0
Provisions, ending balance	2.1	0.8
Included in current liabilities	2.1	0.8
Included in non-current liabilities	0.0	0.0
Employee benefits
Reconciliation of changes in other provisions [abstract]
Provisions, beginning balance	1.1	1.5
Charged to consolidated income statement	0.5	0.0
Credited to consolidated income statement	0.0	(0.4)
Cash payments	(0.5)	0.0
Translation		0.0
Provisions, ending balance	1.1	1.1
Included in current liabilities	0.0	0.0
Included in non-current liabilities	1.1	1.1
Environmental provisions
Reconciliation of changes in other provisions [abstract]
Provisions, beginning balance	0.7	1.2
Charged to consolidated income statement	0.4	0.0
Credited to consolidated income statement	(0.4)	0.0
Cash payments	0.0	(0.3)
Translation		(0.2)
Provisions, ending balance	0.7	0.7
Included in current liabilities	0.7	0.7
Included in non-current liabilities	$ 0.0	$ 0.0

The amount of additional other provisions made. [Refer: Other provisions]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 37
-IssueDate 2017-01-01
-Paragraph 84
-Subparagraph b
-URI http://eifrs.ifrs.org/eifrs/XBRL?type=IAS&num=37&date=2017-03-01&anchor=para_84_b&doctype=Standard
-URIDate 2017-03-09

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- Definition

The amount of current provisions. [Refer: Provisions]

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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- Definition

The increase (decrease) in other provisions resulting from foreign currency exchange rate changes on provisions measured in a currency different from the entity's presentation currency. [Refer: Other provisions]

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- Definition

The increase (decrease) in other provisions resulting from transfers and changes that the entity does not separately disclose in the same statement or note. [Refer: Other provisions]

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The amount of non-current provisions. [Refer: Provisions]

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The amount used (ie incurrent and charged against the provision) for other provisions. [Refer: Other provisions]

+ References

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The amount of liabilities of uncertain timing or the amount recognised when: (a) the entity has a present obligation (legal or constructive) as a result of a past event; (b) it is probable (ie more likely than not) that an outflow of resources embodying economic benefits will be required to settle the obligation; and (c) a reliable estimate can be made of the amount of the obligation.

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