Earnings Per Common Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Computation Of Earnings Per Common Share [Abstract]
Net income	$ 14,216	$ 16,781	$ 15,100	$ 16,751	$ 12,600	$ 14,503	$ 13,178	$ 13,196	$ 62,849	$ 53,477	$ 42,580
Weighted Average Number of Shares Outstanding, Basic	12,683	12,679	12,674	12,665	12,636	12,628	12,619	12,581	12,675	12,616	12,464
Weighted Average Number Diluted Shares Outstanding Adjustment									34	31	49
Weighted Average Number of Shares Outstanding, Diluted, Total	12,721	12,713	12,709	12,695	12,672	12,662	12,648	12,605	12,709	12,647	12,513
Basic EPS	$ 1.12	$ 1.32	$ 1.19	$ 1.32	$ 0.99	$ 1.15	$ 1.04	$ 1.05	$ 4.96	$ 4.24	$ 3.42
Diluted EPS	$ 1.12	$ 1.32	$ 1.19	$ 1.32	$ 0.99	$ 1.15	$ 1.04	$ 1.05	$ 4.95	$ 4.23	$ 3.40
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount									0	0	0