Summary of Significant Accounting Policies - Dilutive Effect of The Company's Stock Options, Restricted Shares, and Performance Shares (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net income (loss)	$ (743)	$ 9,191
Weighted-average common shares outstanding (basic) (in shares)	5,759,000	5,661,000
Effect of dilutive securities:
Weighted-average common shares outstanding (diluted) (in shares)	5,759,000	5,791,000
Net income (loss) per share
Net income (loss) per share – basic (in dollars per share)	$ (0.13)	$ 1.62
Net income (loss) per share – diluted (in dollars per share)	$ (0.13)	$ 1.59
Anti-dilutive weighted-average common shares excluded from calculation of diluted earnings per share (in shares)	412,000	207,000
Restricted shares
Effect of dilutive securities:
Restricted and performance shares (in shares)	0	120,000
Net income (loss) per share
Anti-dilutive weighted-average common shares excluded from calculation of diluted earnings per share (in shares)	0	0
Performance shares
Effect of dilutive securities:
Restricted and performance shares (in shares)	0	10,000