Goodwill and Intangible Assets, net - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Acquired Indefinite-lived Intangible Assets [Line Items]
Amortization expense	$ 18.3	$ 3.4	$ 3.6
Estimated aggregate amortization expense for 2013	35.3
Estimated aggregate amortization expense for 2014	33.8
Estimated aggregate amortization expense for 2015	31.0
Estimated aggregate amortization expense for 2016	27.9
Estimated aggregate amortization expense for 2017	$ 27.3