Net Income (Loss) Per Share - Computation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Mar. 31, 2022	Mar. 31, 2021
Numerator: Basic and Diluted
Net income (loss) - Basic	$ 8,484	$ (3,632)	$ 13,143	$ (11,659)
Net income (loss) - Diluted	8,484	(3,632)	13,143	(11,659)
Dividends paid and accrued	(2,730)	(2,781)	(5,539)	(5,563)
Undistributed income (loss) - Basic	5,754	(6,413)	7,604	(17,222)
Undistributed income (loss) - Diluted	$ 5,754	$ (6,413)	$ 7,604	$ (17,222)
Percentage allocated to common shares	99.00%	100.00%	99.00%	100.00%
Undistributed income (loss) allocated to common shares - Basic	$ 5,697	$ (6,413)	$ 7,525	$ (17,222)
Undistributed income (loss) allocated to common shares - Diluted	5,697	(6,413)	7,525	(17,222)
Dividends paid on common shares outstanding	2,703	2,743	5,482	5,486
Net income (loss) available to common shares - Basic	8,400	(3,670)	13,007	(11,736)
Net income (loss) available to common shares - Diluted	$ 8,400	$ (3,670)	$ 13,007	$ (11,736)
Denominator: Basic and Diluted
Weighted average shares outstanding - Basic (in shares)	12,330,567	12,514,208	12,349,904	12,503,479
Adjustment for dilutive potential common shares (in shares)	143,616		180,938
Weighted average shares outstanding - Diluted (in shares)	12,474,183	12,514,208	12,530,842	12,503,479
Basic net income (loss) per share (in dollars per share)	$ 0.68	$ (0.29)	$ 1.05	$ (0.94)
Diluted net income (loss) per share (in dollars per share)	$ 0.67	$ (0.29)	$ 1.04	$ (0.94)