Goodwill and Other Intangibles - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Finite-Lived Intangible Assets, Amortization Expense, Maturity Schedule [Abstract]
Amortization expense of intangible assets	$ 7.1	$ 5.8	$ 14.5	$ 11.7
Estimated amortization expense, 2013	28.4		28.4
Estimated amortization expense, 2014	28.0		28.0
Estimated amortization expense, 2015	28.0		28.0
Estimated amortization expense, 2016	27.0		27.0
Estimated amortization expense, 2017	27.0		27.0
Estimated amortization expense, 2018	$ 27.0		$ 27.0