Stockholders' Equity (Details) (USD $)	1 Months Ended		12 Months Ended
	May 31, 2012	Nov. 30, 2007	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010	Jun. 30, 2012	Aug. 31, 2010	Sep. 30, 2009
Stockholders' Equity (Textual) [Abstract]
Share price in tender offer			$ 19.00		$ 11.92		$ 12.03	$ 24.13
Stockholders' Equity (Additional Textual) [Abstract]
Stock repurchase program authorized amount	$ 50,000,000	$ 35,000,000
Amount available for repurchases of shares			300,000			55,300,000
Amount of tender offer for repurchases of shares			55,000,000
Common stock repurchased, Shares			2,894,253	0
Common stock repurchased			$ 54,991,000		$ 2,032,000
Number of cumulative shares repurchased			1,303,240
Stock repurchased average price per share			$ 26.86
Maximum [Member]
Stockholders' Equity (Textual) [Abstract]
Share price in tender offer			$ 19.00
Minimum [Member]
Stockholders' Equity (Textual) [Abstract]
Share price in tender offer			$ 17.00