Consolidated Statements of Operations (USD $) In Thousands, except Per Share data	12 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2009
Consolidated Statements of Operations [Abstract]
Net sales	$ 204,160	$ 182,548	$ 165,928
Cost of sales (exclusive of amortization of purchased and core technology shown separately below)	94,702	86,266	80,470
Amortization of purchased and core technology	2,870	4,073	4,193
Gross profit	106,588	92,209	81,265
Operating expenses:
Sales and marketing	39,549	37,010	35,304
Research and development	31,642	27,825	26,381
General and administrative	18,206	17,889	14,557
Restructuring	154	(468)	1,953
Total operating expenses	89,551	82,256	78,195
Operating income	17,037	9,953	3,070
Other (expense) income, net:
Interest income	251	355	1,406
Interest expense	(86)	(138)	(257)
Other (expense) income	(687)	349	63
Total other (expense) income, net	(522)	566	1,212
Income before income taxes	16,515	10,519	4,282
Income tax provision	5,496	1,578	199
Net income	$ 11,019	$ 8,941	$ 4,083
Net income per common share:
Basic	$ 0.44	$ 0.36	$ 0.16
Diluted	$ 0.43	$ 0.36	$ 0.16
Weighted average common shares, basic	25,312	24,865	24,901
Weighted average common shares, diluted	25,819	25,154	25,183