Net Income (Loss) Per Share - Computation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Numerator: Basic and Diluted
Net income (loss) - Basic	$ (8,097)	$ 3,802	$ (761)	$ 3,708
Net income (loss) - Diluted	(8,097)	3,802	(761)	3,708
Dividends	(2,792)	(2,760)	(8,410)	(8,277)
Undistributed income (loss) - Basic	(10,889)	1,042	(9,171)	(4,569)
Undistributed income (loss) - Diluted	$ (10,889)	$ 1,042	$ (9,171)	$ (4,569)
Percentage allocated to common shares	100.00%	98.90%	100.00%	100.00%
Undistributed income (loss) allocated to common shares - Basic	$ (10,889)	$ 1,030	$ (9,171)	$ (4,569)
Undistributed income (loss) allocated to common shares - Diluted	(10,889)	1,030	(9,171)	(4,569)
Dividends paid on common shares outstanding	2,792	2,729	8,410	8,182
Net income (loss) available to common shares - Basic	(8,097)	3,759	(761)	3,613
Net income (loss) available to common shares - Diluted	$ (8,097)	$ 3,759	$ (761)	$ 3,613
Denominator: Basic and Diluted
Weighted average common shares outstanding - Basic	12,475,406	12,449,738	12,469,703	12,443,039
Adjustment for dilutive potential common shares		141,858		148,183
Weighted average shares outstanding - Diluted	12,475,406	12,591,596	12,469,703	12,591,222
Basic net income (loss) per share (in dollars per share)	$ (0.65)	$ 0.30	$ (0.06)	$ 0.29
Diluted net income (loss) per share (in dollars per share)	$ (0.65)	$ 0.30	$ (0.06)	$ 0.29