Goodwill - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended			12 Months Ended
	Sep. 30, 2012	Mar. 31, 2012	Sep. 30, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2013
Goodwill And Intangible Assets Disclosure [Abstract]
Carrying amount of goodwill				$ 0	$ 19.8	$ 0
Goodwill impairment charges	$ 13.2	$ 6.6	$ 3.3	$ 19.8	$ 3.3