Net Income (Loss) Per Share - Computation (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Numerator: Basic and Diluted
Net income (loss) - Basic	$ 15,608	$ 422	$ 28,751	$ (11,237)
Net income (loss) - Diluted	15,608	422	28,751	(11,237)
Dividends paid and accrued	(2,732)	(2,814)	(8,271)	(8,377)
Undistributed income (loss) - Basic	12,876	(2,392)	20,480	(19,614)
Undistributed income (loss) - Diluted	$ 12,876	$ (2,392)	$ 20,480	$ (19,614)
Percentage allocated to common shares	99.00%	100.00%	99.00%	100.00%
Undistributed income (loss) allocated to common shares - Basic	$ 12,749	$ (2,392)	$ 20,271	$ (19,614)
Undistributed income (loss) allocated to common shares - Diluted	12,749	(2,392)	20,271	(19,614)
Dividends paid on common shares outstanding	2,705	2,776	8,187	8,263
Net income (loss) available to common shares - Basic	15,454	384	28,458	(11,351)
Net income (loss) available to common shares - Diluted	$ 15,454	$ 384	$ 28,458	$ (11,351)
Denominator: Basic and Diluted
Weighted average shares outstanding - Basic (in shares)	12,339,308	12,515,161	12,346,372	12,507,373
Adjustment for dilutive potential common shares (in shares)	119,947	161,133	160,566
Weighted average shares outstanding - Diluted (in shares)	12,459,255	12,676,294	12,506,938	12,507,373
Basic net income (loss) per share (in dollars per share)	$ 1.25	$ 0.03	$ 2.30	$ (0.91)
Diluted net income (loss) per share (in dollars per share)	$ 1.24	$ 0.03	$ 2.28	$ (0.91)