Goodwill and Other Intangible Assets - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended		3 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 Acquired intangible assets [Member]
Finite-Lived Intangible Assets [Line Items]
Impairment charge of acquired intangible assets			$ 10.2
Intangible assets, carrying value			0
Gross intangible asset	101.1
Amortization of acquired intangible assets	$ 11.0	$ 35.0