(Loss) Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2019
Numerator:
Net (loss) income available to common shares	$ (68,577)	$ 142,828	$ 39,215
Denominator:
Weighted average common shares (in shares)	29,126,000	29,136,000	28,571,000
Weighted average effect of dilutive securities
Weighted average effect of dilutive securities (in shares)	0	444,000	523,000
Diluted weighted average common shares (in shares)	29,126,000	29,580,000	29,094,000
(Loss) earnings per share:
Basic (in dollars per share)	$ (2.35)	$ 4.90	$ 1.37
Diluted (in dollars per share)	$ (2.35)	$ 4.83	$ 1.35
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding stock options (in shares)	416,000
Stock option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding stock options (in shares)	25,000	102,000	196,000