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
Goodwill and Intangible Assets Disclosure [Line Items]
Estimated future amortization expense for 2013	$ 10.2		$ 10.2
Estimated future amortization expense for 2014	20.4		20.4
Estimated future amortization expense for 2015	11.7		11.7
Estimated future amortization expense for 2016	9.1		9.1
Estimated future amortization expense for 2017	9.0		9.0
Other Intangible Assets
Goodwill and Intangible Assets Disclosure [Line Items]
Amortization expense related to other intangible assets	$ 5.1	$ 5.2	$ 10.3	$ 9.8