Condensed Consolidated Statements Of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2013	Jan. 31, 2012
Net revenue:
Product	$ 132,763	$ 122,189	$ 245,310	$ 236,196
Engineering	5,791	4,244	13,111	8,094
Total net revenue	138,554	126,433	258,421	244,290
Cost of sales:
Product	77,340	75,705	146,014	146,936
Engineering	5,815	3,883	11,922	7,483
Total cost of sales	83,155	79,588	157,936	154,419
Gross profit	55,399	46,845	100,485	89,871
Operating expenses:
Research and product development	16,123	13,940	30,197	29,207
Selling and marketing	11,867	10,605	23,522	21,070
General and administrative	13,606	14,509	25,528	26,219
Total operating expenses	41,596	39,054	79,247	76,496
Income from operations	13,803	7,791	21,238	13,375
Other income (expense):
Interest income, net	95	133	208	269
Gain on sale of other investments		2,500		2,500
Other, net	(497)	322	(1,516)	497
Total other income (expense), net	(402)	2,955	(1,308)	3,266
Income before income taxes	13,401	10,746	19,930	16,641
Provision for (benefit from) income taxes	3,592	(8,869)	5,740	(7,000)
Net income	$ 9,809	$ 19,615	$ 14,190	$ 23,641
Net income per common share:
Basic	$ 0.80	$ 1.61	$ 1.15	$ 1.90
Diluted	$ 0.78	$ 1.59	$ 1.13	$ 1.88
Weighted average shares outstanding:
Basic	12,294	12,188	12,304	12,464
Diluted	12,581	12,333	12,574	12,595
Dividends declared and paid per share	$ 0.10	$ 0.10	$ 0.20	$ 0.20