Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Common Stock	Treasury Stock	Accumulated Other Comprehensive Income	Accumulated Deficit	Total
Beginning balance (in shares) at Sep. 30, 2017	27,028,000
Common Stock, Number of Shares [Abstract]
Stock-based compensation (in shares)	372,000
Stock option exercises (in shares)	6,000
Issuance of common stock - ESPP (in shares)	171,000
Ending balance (in shares) at Sep. 30, 2018	27,577,000
Balance, beginning of period at Sep. 30, 2017	$ 730,906		$ 561	$ (562,972)
Common Stock, Number of Shares [Abstract]
Stock-based compensation	3,648
Stock option exercises	28
Tax withholding paid on behalf of employees for stock-based awards	(1,257)
Issuance of common stock - ESPP	741
Translation adjustment			324		$ 324
Net loss				(17,453)	(17,453)
Balance, end of period at Sep. 30, 2018	$ 734,066	$ (47,721)	885	(580,425)	$ 106,805
Common Stock, Number of Shares [Abstract]
Stock-based compensation (in shares)	307,000
Stock option exercises (in shares)	1,000
Issuance of common stock for acquisition (in shares)	811,000
Issuance of common stock - ESPP (in shares)	197,000
Ending balance (in shares) at Sep. 30, 2019	28,893,000				28,893,000
Common Stock, Number of Shares [Abstract]
Stock-based compensation	$ 2,607
Stock option exercises	1
Tax withholding paid on behalf of employees for stock-based awards	(203)
Issuance of common stock for acquisition	2,951
Issuance of common stock - ESPP	504
Translation adjustment			65		$ 65
Net loss				(35,984)	(35,984)
Balance, end of period at Sep. 30, 2019	$ 739,926	(47,721)	950	(616,409)	$ 76,746
Common Stock, Number of Shares [Abstract]
Stock-based compensation (in shares)	309,000
Stock option exercises (in shares)	1,000				650
Issuance of restricted stock units (shares)	116,000
Issuance of common stock - ESPP (in shares)	231,000
Ending balance (in shares) at Sep. 30, 2020	29,550,000				29,551,000
Common Stock, Number of Shares [Abstract]
Stock-based compensation	$ 3,517
Stock option exercises	2
Tax withholding paid on behalf of employees for stock-based awards	(111)
Issuance of restricted stock units	410
Issuance of common stock - ESPP	617
Translation adjustment			(32)		$ (32)
Net loss				(7,000)	(7,000)
Balance, end of period at Sep. 30, 2020	$ 744,361	$ (47,721)	$ 918	$ (623,409)	$ 74,149