Goodwill - Summary of Goodwill (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Goodwill and Intangible Assets Disclosure [Abstract]
At January 1, Gross cost			$ 424.4	$ 384.2
At January 1, Accumulated impairment losses			(236.5)	(235.2)
At January 1, Net book amount			187.9	149.0
Exchange effect			(0.3)	(0.1)
Acquisitions			0	17.0
Adjustments to purchase price allocation			0.3	0.4
Impairment losses	0	(0.4)	0	(1.0)
At September 30, Gross cost	424.4	401.5	424.4	401.5
At September 30, Accumulated impairment losses	(236.5)	(236.2)	(236.5)	(236.2)
At September 30, Net book amount	$ 187.9	$ 165.3	$ 187.9	$ 165.3

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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-Publisher FASB

-Name Accounting Standards Codification

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-SubTopic 20

-Section 50

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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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Amount before accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of accumulated impairment loss for an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of increase (decrease) from adjustments after acquisition date under purchase accounting of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of increase (decrease) from foreign currency translation adjustments of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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