Condensed Consolidated Statements of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Treasury Stock	Accumulated other comprehensive income	Accumulated deficit
Beginning balance (in shares) at Sep. 30, 2020		29,551
Shares of common stock
Stock-based compensation (in shares)		433
Stock option exercises (in shares)		10
Issuance of common stock - ESPP (in shares)		126
Sale of common stock (in shares)		6,655
Ending balance (in shares) at Mar. 31, 2021		36,775
Balance, beginning of period at Sep. 30, 2020		$ 744,361	$ (47,721)	$ 918	$ (623,409)
Shares of common stock
Stock-based compensation		1,834
Stock option exercises		46
Tax withholding paid on behalf of employees for stock-based awards		(83)
Issuance of common stock - ESPP		382
Sale of common stock, net of offering costs		33,141
Translation adjustment	$ (21)			(21)
Net (loss) income	6,953				6,953
Balance, end of period at Mar. 31, 2021	116,401	$ 779,681	(47,721)	897	(616,456)
Beginning balance (in shares) at Dec. 31, 2020		29,783
Shares of common stock
Stock-based compensation (in shares)		203
Stock option exercises (in shares)		8
Issuance of common stock - ESPP (in shares)		126
Sale of common stock (in shares)		6,655
Ending balance (in shares) at Mar. 31, 2021		36,775
Balance, beginning of period at Dec. 31, 2020		$ 745,188	(47,721)	908	(620,840)
Shares of common stock
Stock-based compensation		931
Stock option exercises		39
Tax withholding paid on behalf of employees for stock-based awards		0
Issuance of common stock - ESPP		382
Sale of common stock, net of offering costs		33,141
Translation adjustment	(11)			(11)
Net (loss) income	4,384				4,384
Balance, end of period at Mar. 31, 2021	$ 116,401	$ 779,681	(47,721)	897	(616,456)
Beginning balance (in shares) at Sep. 30, 2021	36,984	36,984
Shares of common stock
Stock-based compensation (in shares)		405
Stock option exercises (in shares)		6
Issuance of common stock - ESPP (in shares)		0
Sale of common stock (in shares)		0
Ending balance (in shares) at Mar. 31, 2022	37,395	37,395
Balance, beginning of period at Sep. 30, 2021		$ 782,266	(47,721)	687	(597,766)
Shares of common stock
Stock-based compensation		2,232
Stock option exercises		29
Tax withholding paid on behalf of employees for stock-based awards		(156)
Issuance of common stock - ESPP		0
Sale of common stock, net of offering costs		0
Translation adjustment	$ 22			22
Net (loss) income	189				189
Balance, end of period at Mar. 31, 2022	$ 139,782	$ 784,371	(47,721)	709	(597,577)
Beginning balance (in shares) at Dec. 31, 2021		37,275
Shares of common stock
Stock-based compensation (in shares)		120
Stock option exercises (in shares)		0
Issuance of common stock - ESPP (in shares)		0
Sale of common stock (in shares)		0
Ending balance (in shares) at Mar. 31, 2022	37,395	37,395
Balance, beginning of period at Dec. 31, 2021		$ 783,329	(47,721)	707	(595,352)
Shares of common stock
Stock-based compensation		1,144
Stock option exercises		0
Tax withholding paid on behalf of employees for stock-based awards		(102)
Issuance of common stock - ESPP		0
Sale of common stock, net of offering costs		0
Translation adjustment	$ 2			2
Net (loss) income	(2,225)				(2,225)
Balance, end of period at Mar. 31, 2022	$ 139,782	$ 784,371	$ (47,721)	$ 709	$ (597,577)