Goodwill and Other Intangibles - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Goodwill and Intangible Assets Disclosure [Line Items]
Estimated future amortization expense for 2014	$ 4.8		$ 4.8
Estimated future amortization expense for 2015	11.5		11.5
Estimated future amortization expense for 2016	9.0		9.0
Estimated future amortization expense for 2017	8.9		8.9
Estimated future amortization expense for 2018	8.2		8.2
Other Intangible Assets
Goodwill and Intangible Assets Disclosure [Line Items]
Amortization expense related to other intangible assets	$ 4.8	$ 5.2	$ 14.7	$ 15.5