CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (USD $) In Thousands, except Share data	3 Months Ended		6 Months Ended
	Aug. 31, 2011	Aug. 31, 2010	Aug. 31, 2011	Aug. 31, 2010
CONSOLIDATED STATEMENTS OF OPERATIONS [Abstract]
Sales and revenues	$ 112,581	$ 104,084	$ 216,076	$ 201,243
Costs of goods sold	52,237	45,426	99,947	90,790
Gross profit on sales and revenues	60,344	58,658	116,129	110,453
Operating expenses:
Research and development	22,632	19,763	47,159	43,582
Selling, general and administrative	16,234	16,045	39,463	41,399
Restructuring charges	356	47	699	868
Revaluation of contingent consideration	(398)	457	(381)	457
Income from operations	21,520	22,346	29,189	24,147
Interest income	69	174	187	318
Interest expense	(39)	(66)	(76)	(95)
Other (expense) income, net	(99)	(181)	43	(336)
Income before income taxes	21,451	22,273	29,343	24,034
Provision for income taxes	9,560	9,371	11,274	10,505
Net income	$ 11,891	$ 12,902	$ 18,069	$ 13,529
Net income per share:
Basic	$ 0.52	$ 0.57	$ 0.78	$ 0.60
Diluted	$ 0.51	$ 0.57	$ 0.77	$ 0.59
Weighted average common shares outstanding:
Basic	23,065	22,606	23,047	22,540
Diluted	23,493	22,756	23,516	22,772