Net Income (Loss) Per Share - Computation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Numerator: Basic and Diluted
Net income (loss) - Basic	$ (3,632)	$ 4,068	$ (11,659)	$ 7,336
Net income (loss) - Diluted			(11,659)	7,336
Dividends	(2,781)	(2,781)	(5,563)	(5,618)
Undistributed income (loss) - Basic	$ (6,413)	$ 1,287	(17,222)	1,718
Undistributed income (loss) - Diluted			$ (17,222)	$ 1,718
Percentage allocated to common shares	100.00%	99.30%	100.00%	99.30%
Undistributed income (loss) allocated to common shares - Basic	$ (6,413)	$ 1,279	$ (17,222)	$ 1,707
Undistributed income (loss) allocated to common shares - Diluted			(17,222)	1,707
Dividends paid on common shares outstanding	2,743	2,763	5,486	5,581
Net income (loss) available to common shares - Basic	$ (3,670)	$ 4,042	(11,736)	7,288
Net income (loss) available to common shares - Diluted			$ (11,736)	$ 7,288
Denominator: Basic and Diluted
Weighted average common shares outstanding - Basic	12,514,208	12,473,881	12,503,479	12,466,867
Adjustment for dilutive potential common shares		30,182		30,082
Weighted average shares outstanding - Diluted	12,514,208	12,504,063	12,503,479	12,496,949
Basic net income (loss) per share (in dollars per share)	$ (0.29)	$ 0.32	$ (0.94)	$ 0.58
Diluted net income (loss) per share (in dollars per share)	$ (0.29)	$ 0.32	$ (0.94)	$ 0.58