Net Income (Loss) Per Share - Computation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Numerator: Basic and Diluted
Net income (loss) - Basic	$ 3,802	$ 713	$ 3,708	$ (23,881)
Net income (loss) - Diluted	3,802	713	3,708	(23,881)
Dividends	(2,760)	(2,756)	(8,277)	(8,272)
Undistributed income (loss) - Basic	1,042	(2,043)	(4,569)	(32,153)
Undistributed income (loss) - Diluted	$ 1,042	$ (2,043)	$ (4,569)	$ (32,153)
Percentage allocated to common shares	98.90%	100.00%	100.00%	100.00%
Undistributed income (loss) allocated to common shares - Basic	$ 1,030	$ (2,043)	$ (4,569)	$ (32,153)
Undistributed income (loss) allocated to common shares - Diluted	1,030	(2,043)	(4,569)	(32,153)
Dividends paid on common shares outstanding	2,729	2,731	8,182	8,196
Net income (loss) available to common shares - Basic	3,759	688	3,613	(23,957)
Net income (loss) available to common shares - Diluted	$ 3,759	$ 688	$ 3,613	$ (23,957)
Denominator: Basic and Diluted
Weighted average common shares outstanding - Basic	12,449,738	12,422,485	12,443,039	12,418,579
Adjustment for dilutive potential common shares	141,858	7,144	148,183
Weighted average shares outstanding - Diluted	12,591,596	12,429,629	12,591,222	12,418,579
Basic net income (loss) per share (in dollars per share)	$ 0.30	$ 0.06	$ 0.29	$ (1.93)
Diluted net income (loss) per share (in dollars per share)	$ 0.30	$ 0.06	$ 0.29	$ (1.93)