Summary of Significant Accounting Policies (Details 6) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011
Numerator:
Net income	$ 5,835	$ 4,009	$ 5,297	$ 6,436	$ 12,856	$ 13,732	$ 15,151	$ 8,443	$ 21,577	$ 50,182	$ 31,128
Less amount allocable to participating securities									(186)	(454)	(320)
Net income available for basic shareholders									21,391	49,728	30,808
Adjustment for dilutive potential common shares										2	(2)
Net income available for diluted common shares									$ 21,391	$ 49,730	$ 30,806
Denominator:
Weighted average shares - Basic									12,223,838	12,147,179	12,067,555
Adjustment for dilutive potential common shares									41,792	68,852	82,311
Weighted average shares - Diluted									12,265,630	12,216,031	12,149,866
Basic net income per share (in dollars per share)	$ 0.47	$ 0.33	$ 0.43	$ 0.52	$ 1.05	$ 1.12	$ 1.24	$ 0.69	$ 1.75	$ 4.09	$ 2.55
Diluted net income per share (in dollars per share)	$ 0.47	$ 0.32	$ 0.43	$ 0.52	$ 1.04	$ 1.11	$ 1.23	$ 0.68	$ 1.74	$ 4.07	$ 2.54
Number of stock option shares excluded as their effect would be anti-dilutive									170,623	98,630	130,195