Stockholders' Equity (Details) (USD $)	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2010
Summary of the activity with respect to stock options
Outstanding, Number, Beginning Balance	345,600	817,400	936,500
Granted	0	0	126,000
Exercised	(99,644)	(467,800)	(244,900)
Forfeited	0	(4,000)	(200)
Expired	0	0	0
Outstanding, Number, Ending Balance	245,956	345,600	817,400
Options, Outstanding, Weighted Average Exercise Price, Beginning Balance	$ 13.82	$ 9.26	$ 7.05
Granted, Weighted Average Exercise Price	$ 0.00	$ 0.00	$ 25.04
Exercised, Weighted Average Exercise Price	$ 13.63	$ 5.89	$ 8.93
Forfeited, Weighted Average Exercise Price	$ 0.00	$ 8.78	$ 5.63
Expired, Weighted Average Exercise Price	$ 0.00	$ 0.00	$ 0.00
Options, Outstanding, Weighted Average Exercise Price, Ending Balance	$ 13.90	$ 13.82	$ 9.26