Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2020	Mar. 31, 2019
Numerator:
Net income (loss)	$ 7,421	$ 2,775	$ 958	$ (2,695)	$ 10,196	$ (1,737)
Denominator:
Weighted average basic shares (in shares)	11,621		11,570		11,617	11,560
Dilutive effect of restricted stock units (in shares)	60		62		56	0
Weighted average diluted shares (in shares)	11,681		11,632		11,673	11,560
Income (loss) per share:
Basic (in dollars per share)	$ 0.64		$ 0.08		$ 0.88	$ (0.15)
Diluted (in dollars per share)	$ 0.64		$ 0.08		$ 0.87	$ (0.15)