Goodwill and Intangible Assets - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012
Goodwill And Intangible Assets Disclosure [Abstract]
Amortization expense associated with identifiable intangible assets	$ 1.2	$ 0.7
Estimated total amortization expense 2013	2.6
Estimated total amortization expense 2014	2.5
Estimated total amortization expense 2015	2.5
Estimated total amortization expense 2016	0.9
Estimated total amortization expense 2017	$ 0.5