Consolidated Statement of Shareholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income [Member]	Accumulated Deficit [Member]
Beginning balance (in shares) at Sep. 30, 2014	31,109,000
Balance as of September 30, 2014 at Sep. 30, 2014	$ 112,347	$ 755,368	$ (2,071)	$ 1,837	$ (642,787)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	63,100				63,100
Translation adjustment	(990)			(990)
Stock-based compensation (in shares)		948,000
Stock-based compensation	4,320	$ 4,320
Purchase of treasury stock (in shares)			(6,870,000)
Purchase of treasury stock	(45,650)		$ (45,650)
Stock option exercises (in shares)		290,000
Stock option exercises	1,409	$ 1,409
Issuance of common stock - ESPP (in shares)		121,000
Issuance of common stock - ESPP	493	$ 493
Issuance of common stock - Board of Directors (in shares)		78,000
Issuance of common stock - Board of Directors	$ 413	$ 413
Ending balance (in shares) at Sep. 30, 2015	25,676,000
Balance as of September 30, 2015 at Sep. 30, 2015	$ 135,442	$ 762,003	(47,721)	847	(579,687)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	8,266				8,266
Translation adjustment	(268)			(268)
Stock-based compensation (in shares)		284,000
Stock-based compensation	1,868	$ 1,868
Stock option exercises (in shares)		45,000
Stock option exercises	225	$ 225
Special dividend paid	(39,214)	$ (39,214)
Issuance of common stock - ESPP (in shares)		193,000
Issuance of common stock - ESPP	735	$ 735
Issuance of common stock - Board of Directors (in shares)		46,000
Issuance of common stock - Board of Directors	$ 263	$ 263
Ending balance (in shares) at Sep. 30, 2016	26,244,000
Balance as of September 30, 2015 at Sep. 30, 2016	$ 107,317	725,666	(47,721)	579	(571,207)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative adjustment for adoption of accounting standard		$ (214)			214
Net income	8,235				8,235
Translation adjustment	(18)			(18)
Stock-based compensation (in shares)		432,000
Stock-based compensation	$ 3,602	$ 3,602
Stock option exercises (in shares)	157,879	158,000
Stock option exercises	$ 534	$ 534
Issuance of common stock - ESPP (in shares)		133,000
Issuance of common stock - ESPP	773	$ 773
Issuance of common stock - Board of Directors (in shares)		61,000
Issuance of common stock - Board of Directors	$ 331	$ 331
Ending balance (in shares) at Sep. 30, 2017	27,028,000
Balance as of September 30, 2015 at Sep. 30, 2017	$ 120,774	$ 730,906	$ (47,721)	$ 561	$ (562,972)