Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended								12 Months Ended
	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share [Abstract]
Net income (loss)	$ 1,539	$ 301	$ (3,330)	$ (5,662)	$ (5,142)	$ (3,215)	$ (829)	$ (300)	$ (7,152)	$ (9,486)	$ 15,510
Denominator:
Weighted average basic shares (in shares)									11,507	11,453	11,400
Dilutive effect of restricted stock units (in shares)									0	0	31
Weighted average diluted shares with assumed conversions									11,507	11,453	11,431
Net earnings (loss) per share:
Basic earnings (loss) per share (in dollars per share)	$ 0.13	$ 0.03	$ (0.29)	$ (0.49)	$ (0.45)	$ (0.28)	$ (0.07)	$ (0.03)	$ (0.62)	$ (0.83)	$ 1.36
Diluted earnings (loss) per share (in dollars per share)	$ 0.13	$ 0.03	$ (0.29)	$ (0.49)	$ (0.45)	$ (0.28)	$ (0.07)	$ (0.03)	$ (0.62)	$ (0.83)	$ 1.36