Stockholders Equity - Additional Information (Detail) (USD $)	1 Months Ended		12 Months Ended			1 Months Ended					12 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Sep. 30, 2013	Sep. 30, 2012	Jun. 30, 2012	Nov. 30, 2007 November 2007 authorization plan [Member]	Jun. 30, 2013 May 2012 authorization plan [Member]	May 31, 2012 May 2012 authorization plan [Member]	Jun. 30, 2013 January 2013 authorization plan [Member]	Jul. 29, 2013 July 2013 authorization plan [Member]	Sep. 30, 2013 Open Market Share Repurchase Program [Member]	Sep. 30, 2012 Maximum [Member]	Sep. 30, 2012 Minimum [Member]
Stockholders Equity [Line Items]
Stock repurchase program authorized amount						$ 35,000,000		$ 50,000,000	$ 10,000,000	$ 20,000,000
Amount available for repurchases of shares	11,500,000		11,500,000		55,300,000
Amount of tender offer for repurchases of shares				55,000,000
Share price in tender offer												$ 19.00	$ 17.00
Common stock repurchased, Shares	390,353		795,643	2,894,253
Common stock repurchased			$ 18,809,000	$ 54,991,000			$ 300,000				$ 1,000,000
Number of cumulative shares repurchased		405,290		1,303,240
Stock repurchased average price per share		$ 25.47		$ 26.86
Stock repurchased average price per share	$ 21.71