Summary of Significant Accounting Policies (Details 9) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2013
Numerator: Basic and Diluted
Net income	$ 5,784	$ 6,602	$ 11,719	$ 6,381	$ 6,370	$ 2,096	$ (1,223)	$ (3,492)	$ 30,486	$ 3,751	$ 21,577
Dividends paid									(10,952)	(10,906)	(10,849)
Undistributed income (loss)									$ 19,534	$ (7,155)	$ 10,728
Percentage allocated to common shares									99.10%	99.20%	99.10%
Undistributed income (loss) allocated to common shares									$ 19,358	$ (7,098)	$ 10,637
Dividends paid on common shares outstanding									10,853	10,819	10,754
Net income (loss) available to common shares									$ 30,211	$ 3,721	$ 21,391
Denominator: Basic and Diluted
Weighted average common shares outstanding									12,331,805	12,291,881	12,223,838
Adjustment for dilutive potential common shares									12,404	29,819	41,792
Weighted average shares - Diluted									12,344,209	12,321,700	12,265,630
Basic net income (loss) per share (in dollars per share)	$ 0.46	$ 0.53	$ 0.94	$ 0.51	$ 0.51	$ 0.17	$ (0.10)	$ (0.29)	$ 2.45	$ 0.30	$ 1.75
Diluted net income (loss) per share (in dollars per share)	$ 0.46	$ 0.53	$ 0.94	$ 0.51	$ 0.51	$ 0.17	$ (0.10)	$ (0.29)	$ 2.45	$ 0.30	$ 1.74