Condensed Consolidated Statements of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Treasury Stock	Accumulated Other Comprehensive Income	Accumulated Deficit
Beginning balance (in shares) at Sep. 30, 2017		27,028,000
Common Stock, Number of Shares [Abstract]
Stock-based compensation (in shares)		333,000
Stock option exercises (in shares)		4,000
Issuance of common stock - ESPP (in shares)		93,000
Ending balance (in shares) at Mar. 31, 2018		27,458,000
Beginning balance at Sep. 30, 2017		$ 730,906	$ (47,721)	$ 561	$ (562,972)
Common Stock, Number of Shares [Abstract]
Stock-based compensation		1,848
Stock option exercises		17
Tax withholding paid on behalf of employees for stock-based awards		(1,139)
Issuance of common stock - ESPP		423
Translation adjustment				374
Net loss	$ (3,153)				(3,153)
Ending balance at Mar. 31, 2018	$ 119,144	$ 732,055	(47,721)	935	(566,125)
Beginning balance (in shares) at Sep. 30, 2017		27,028,000
Ending balance (in shares) at Sep. 30, 2018	27,577,000	27,577,000
Beginning balance at Sep. 30, 2017		$ 730,906	(47,721)	561	(562,972)
Common Stock, Number of Shares [Abstract]
Translation adjustment	$ 374
Net loss	(3,153)
Ending balance at Sep. 30, 2018		$ 734,066	(47,721)	885	(580,425)
Beginning balance (in shares) at Dec. 31, 2017		27,152,000
Common Stock, Number of Shares [Abstract]
Stock-based compensation (in shares)		212,000
Stock option exercises (in shares)		1,000
Issuance of common stock - ESPP (in shares)		93,000
Ending balance (in shares) at Mar. 31, 2018		27,458,000
Beginning balance at Dec. 31, 2017		$ 731,112	(47,721)	814	(563,054)
Common Stock, Number of Shares [Abstract]
Stock-based compensation		933
Stock option exercises		1
Tax withholding paid on behalf of employees for stock-based awards		(414)
Issuance of common stock - ESPP		423
Translation adjustment	121			121
Net loss	(3,071)				(3,071)
Ending balance at Mar. 31, 2018	$ 119,144	$ 732,055	(47,721)	935	(566,125)
Beginning balance (in shares) at Sep. 30, 2018	27,577,000	27,577,000
Common Stock, Number of Shares [Abstract]
Stock-based compensation (in shares)		212,000
Stock option exercises (in shares)	208	1,000
Issuance of common stock - ESPP (in shares)		66,000
Ending balance (in shares) at Mar. 31, 2019	27,856,000	27,856,000
Beginning balance at Sep. 30, 2018		$ 734,066	(47,721)	885	(580,425)
Common Stock, Number of Shares [Abstract]
Stock-based compensation		1,147
Stock option exercises		1
Tax withholding paid on behalf of employees for stock-based awards		(194)
Issuance of common stock - ESPP		237
Translation adjustment	$ 27			27
Net loss	(10,532)				(10,532)
Ending balance at Mar. 31, 2019	$ 97,491	$ 735,257	(47,721)	912	(590,957)
Beginning balance (in shares) at Dec. 31, 2018		27,668,000
Common Stock, Number of Shares [Abstract]
Stock-based compensation (in shares)		121,000
Stock option exercises (in shares)		1,000
Issuance of common stock - ESPP (in shares)		66,000
Ending balance (in shares) at Mar. 31, 2019	27,856,000	27,856,000
Beginning balance at Dec. 31, 2018		$ 734,341	(47,721)	899	(585,963)
Common Stock, Number of Shares [Abstract]
Stock-based compensation		722
Stock option exercises		1
Tax withholding paid on behalf of employees for stock-based awards		(44)
Issuance of common stock - ESPP		237
Translation adjustment	$ 13			13
Net loss	(4,994)				(4,994)
Ending balance at Mar. 31, 2019	$ 97,491	$ 735,257	$ (47,721)	$ 912	$ (590,957)