Consolidated Statements of Stockholders' Equity and Comprehensive Income (Loss) (USD $) In Thousands	Total	Common Stock	Treasury Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)
Balance at Sep. 30, 2008	$ 231,934	$ 283	$ (22,691)	$ 177,614	$ 78,625	$ (1,897)
Balance, shares at Sep. 30, 2008		28,336	2,960
Net income	4,083				4,083
Foreign currency translation adjustment	(4,622)					(4,622)
Net unrealized (loss) gain on investments (net of related tax effect of $2, $(22) and $66 for the year ended 2009, 2010 and 2011 respectively)	(4)					(4)
Reclassification of (gain) loss into net income (net of related tax effect of $3, $14 and $(4) for the year ended 2009, 2010 and 2011 respectively)	(4)					(4)
Total comprehensive income (loss)	(547)
Employee stock purchase issuances	982		1,106	(124)
Employee stock purchase issuances, shares			(145)
Purchase of treasury stock	(6,576)		(6,576)
Purchase of treasury stock, shares			893
Issuance of stock upon exercise of stock options	423	1		422
Issuance of stock upon exercise of stock options, shares		73
Tax benefit realized upon exercise of stock options	(148)			(148)
Stock-based compensation expense	3,518			3,518
Balance at Sep. 30, 2009	229,586	284	(28,161)	181,282	82,708	(6,527)
Balance, shares at Sep. 30, 2009		28,409	3,708
Net income	8,941				8,941
Foreign currency translation adjustment	(3,074)					(3,074)
Net unrealized (loss) gain on investments (net of related tax effect of $2, $(22) and $66 for the year ended 2009, 2010 and 2011 respectively)	34					34
Reclassification of (gain) loss into net income (net of related tax effect of $3, $14 and $(4) for the year ended 2009, 2010 and 2011 respectively)	(22)					(22)
Total comprehensive income (loss)	5,879
Employee stock purchase issuances	894		943	(49)
Employee stock purchase issuances, shares			(124)
Issuance of stock upon exercise of stock options	1,672	3		1,669
Issuance of stock upon exercise of stock options, shares		257
Tax benefit realized upon exercise of stock options	(846)			(846)
Stock-based compensation expense	3,371			3,371
Balance at Sep. 30, 2010	240,556	287	(27,218)	185,427	91,649	(9,589)
Balance, shares at Sep. 30, 2010		28,666	3,584
Net income	11,019				11,019
Foreign currency translation adjustment	(770)					(770)
Net unrealized (loss) gain on investments (net of related tax effect of $2, $(22) and $66 for the year ended 2009, 2010 and 2011 respectively)	(104)					(104)
Reclassification of (gain) loss into net income (net of related tax effect of $3, $14 and $(4) for the year ended 2009, 2010 and 2011 respectively)	6					6
Total comprehensive income (loss)	10,151
Employee stock purchase issuances	990		852	138
Employee stock purchase issuances, shares			(112)
Issuance of stock upon exercise of stock options	2,853	4		2,849
Issuance of stock upon exercise of stock options, shares		435
Tax benefit realized upon exercise of stock options	2,722			2,722
Stock-based compensation expense	3,444			3,444
Balance at Sep. 30, 2011	$ 260,716	$ 291	$ (26,366)	$ 194,580	$ 102,668	$ (10,457)
Balance, shares at Sep. 30, 2011		29,101	3,472