Income per Common Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net Income available to common shareholders (in thousands)	$ 8,449	$ 7,249	$ 24,905	$ 19,849
Weighted average common shares outstanding (shares)	28,959,905	27,564,055	28,781,152	27,620,817
Effect of dilutive securities
Options (shares)	1,750,153	1,711,298	1,706,328	1,319,482
Weighted average common and potential shares outstanding (shares)	30,710,058	29,275,353	30,487,480	28,940,299
Basic income per share (usd per share)	$ 0.29	$ 0.26	$ 0.87	$ 0.72
Diluted income per share (usd per share)	$ 0.28	$ 0.25	$ 0.82	$ 0.69
Exercise price, lower range (usd per share)	$ 18.58	$ 10.00	$ 13.32	$ 6.73
Exercise price, upper limit (usd per share)	$ 26.76	$ 18.71	$ 26.76	$ 18.71
Stock Options
Effect of dilutive securities
Options to purchase shares of common stock (shares)	7,846	272,167	37,292	896,033