Treasury Stock - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	1 Months Ended	3 Months Ended		9 Months Ended
	Oct. 31, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Treasury Stock Textual [Abstract]
Share repurchase program, new limit amount	$ 25.0
Treasury stock, shares purchased		0	0	0	0