Goodwill and Intangible Assets - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Goodwill And Intangible Assets Disclosure [Abstract]
Goodwill and intangible assets with indefinite lives	$ 59.7		$ 59.7
Amortization expense associated with identifiable intangible assets	0.6	0.2
Estimated total amortization expense 2014	2.3
Estimated total amortization expense 2015	2.3
Estimated total amortization expense 2016	0.7
Estimated total amortization expense 2017	0.4
Estimated total amortization expense 2018	$ 0.4