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)		360,000
Stock option exercises (in shares)		5,000
Issuance of common stock for acquisition (in shares)		0
Issuance of common stock - ESPP (in shares)		93,000
Ending balance (in shares) at Jun. 30, 2018		27,486,000
Beginning balance at Sep. 30, 2017		$ 730,906	$ (47,721)	$ 561	$ (562,972)
Common Stock, Number of Shares [Abstract]
Stock-based compensation		2,713
Stock option exercises		21
Tax withholding paid on behalf of employees for stock-based awards		(1,257)
Issuance of common stock for acquisition		0
Issuance of common stock - ESPP		423
Translation adjustment	$ 320			320
Net loss	(11,567)				(11,567)
Ending balance at Jun. 30, 2018	111,427	$ 732,806	(47,721)	881	(574,539)
Beginning balance (in shares) at Mar. 31, 2018		27,458,000
Common Stock, Number of Shares [Abstract]
Stock-based compensation (in shares)		27,000
Stock option exercises (in shares)		1,000
Issuance of common stock for acquisition (in shares)		0
Issuance of common stock - ESPP (in shares)
Ending balance (in shares) at Jun. 30, 2018		27,486,000
Beginning balance at Mar. 31, 2018		$ 732,056	(47,721)	935	(566,125)
Common Stock, Number of Shares [Abstract]
Stock-based compensation		864
Stock option exercises		4
Tax withholding paid on behalf of employees for stock-based awards		(118)
Issuance of common stock for acquisition		0
Issuance of common stock - ESPP		0
Translation adjustment	(54)			(54)
Net loss	(8,414)				(8,414)
Ending balance at Jun. 30, 2018	$ 111,427	$ 732,806	(47,721)	881	(574,539)
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)		305,000
Stock option exercises (in shares)	208	1,000
Issuance of common stock for acquisition (in shares)		811,000
Issuance of common stock - ESPP (in shares)		66,000
Ending balance (in shares) at Jun. 30, 2019	28,760,000	28,760,000
Beginning balance at Sep. 30, 2018		$ 734,066	(47,721)	885	(580,425)
Common Stock, Number of Shares [Abstract]
Stock-based compensation		1,824
Stock option exercises		1
Tax withholding paid on behalf of employees for stock-based awards		(203)
Issuance of common stock for acquisition		2,916
Issuance of common stock - ESPP		237
Translation adjustment	$ 36			36
Net loss	(21,009)				(21,009)
Ending balance at Jun. 30, 2019	$ 90,607	$ 738,841	(47,721)	921	(601,434)
Beginning balance (in shares) at Mar. 31, 2019		27,856,000
Common Stock, Number of Shares [Abstract]
Stock-based compensation (in shares)		93,000
Stock option exercises (in shares)		0
Issuance of common stock - ESPP (in shares)
Ending balance (in shares) at Jun. 30, 2019	28,760,000	28,760,000
Beginning balance at Mar. 31, 2019		$ 735,257	(47,721)	912	(590,957)
Common Stock, Number of Shares [Abstract]
Stock-based compensation		677
Stock option exercises		0
Tax withholding paid on behalf of employees for stock-based awards		(9)
Issuance of common stock - ESPP		0
Translation adjustment	$ 9			9
Net loss	(10,477)				(10,477)
Ending balance at Jun. 30, 2019	$ 90,607	$ 738,841	$ (47,721)	$ 921	$ (601,434)