Goodwill - Summarizes Goodwill Movement (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Goodwill And Intangible Assets Disclosure [Abstract]
At January 1, Gross cost			$ 384.2	$ 375.5
At January 1, Accumulated impairment losses			(235.2)	(234.0)
At January 1, Net book amount			149.0	141.5
Exchange effect			(0.1)	(0.1)
Acquisitions			17.0	0
Adjustments to purchase price allocation			0.4	0
Impairment losses	(0.4)	(0.3)	(1.0)	(0.9)
At September 30, Gross cost	401.5	375.4	401.5	375.4
At September 30, Accumulated impairment losses	(236.2)	(234.9)	(236.2)	(234.9)
At September 30, Net book amount	$ 165.3	$ 140.5	$ 165.3	$ 140.5