Subsequent Events - Additional Information (Detail) (USD $)	9 Months Ended				0 Months Ended
	Sep. 30, 2014	Oct. 31, 2013	Oct. 31, 2012	Oct. 31, 2011	Oct. 28, 2014 Subsequent Event [Member]	Oct. 28, 2014 Subsequent Event [Member] Dividend Declared [Member]	Oct. 28, 2014 Subsequent Event [Member] Extraordinary Dividend [Member]
Subsequent Event [Line Items]
Cash dividend per share						$ 0.12
Date of payment to shareholders entitled to dividends						Dec. 26, 2014	Dec. 26, 2014
Date of record of shareholders entitled to dividends						Dec. 12, 2014	Dec. 12, 2014
Extraordinary cash dividends declared per common share	$ 0.50						$ 1.00
Share repurchase program limit amount		$ 25,000,000	$ 25,000,000	$ 25,000,000	$ 25,000,000
Share repurchase program expiration date	Dec. 31, 2014				Dec. 31, 2015