Condensed Consolidated Statements of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Common Stock	Treasury Stock	Accumulated Other Comprehensive Income	Accumulated Deficit	Total
Beginning balance (in shares) at Sep. 30, 2019	28,893
Common Stock, Number of Shares [Abstract]
Stock-based compensation (in shares)	55
Stock option exercises (in shares)	0
Ending balance (in shares) at Dec. 31, 2019	28,948
Balance, beginning of period at Sep. 30, 2019	$ 739,926		$ 950	$ (616,409)
Common Stock, Number of Shares [Abstract]
Stock-based compensation	801
Stock option exercises	0
Tax withholding paid on behalf of employees for stock-based awards	(47)
Translation adjustment			(36)		$ (36)
Net loss				(1,335)	(1,335)
Balance, end of period at Dec. 31, 2019	$ 740,680	$ (47,721)	914	(617,744)	$ 76,129
Beginning balance (in shares) at Sep. 30, 2020	29,551				29,551
Common Stock, Number of Shares [Abstract]
Stock-based compensation (in shares)	230
Stock option exercises (in shares)	2
Ending balance (in shares) at Dec. 31, 2020	29,783				29,783
Balance, beginning of period at Sep. 30, 2020	$ 744,361		918	(623,409)
Common Stock, Number of Shares [Abstract]
Stock-based compensation	903
Stock option exercises	7
Tax withholding paid on behalf of employees for stock-based awards	(83)
Translation adjustment			(10)		$ (10)
Net loss				2,569	2,569
Balance, end of period at Dec. 31, 2020	$ 745,188	$ (47,721)	$ 908	$ (620,840)	$ 77,535