Consolidated Statements of Income (USD $)	12 Months Ended
	Apr. 26, 2013		Apr. 27, 2012		Apr. 29, 2011
Consolidated Statements of Income [Abstract]
Net sales	$ 254,320,417		$ 218,502,731		$ 190,464,398
Cost of sales	21,907,264		19,656,332		23,020,032
Gross profit	232,413,153		198,846,399		167,444,366
Operating expenses:
Selling, general and administrative	112,515,262		102,568,776		89,654,039
Research and development	41,551,444		35,334,770		28,602,684
Total operating expenses	154,066,706		137,903,546		118,256,723
Income from operations	78,346,447		60,942,853		49,187,643
Interest income	84,287		326,118		262,298
Interest expense	(119,303)		(296,725)		(397,975)
Impairment of investment	(4,058,768)		0		0
Gain on warrants' liability	1,325,574		0		0
Other expense, net	(303,612)		(550,818)		(387,035)
Income before income taxes	75,274,625		60,421,428		48,664,931
Income tax expense	28,917,123		24,343,696		1,939,221
Net income	$ 46,357,502		$ 36,077,732		$ 46,725,710
Basic income per share (in Dollars per Share)	$ 1.68		$ 1.30		$ 1.67
Diluted income per share (in Dollars per Share)	$ 1.66	[1]	$ 1.28	[1]	$ 1.64
Shares used in computing basic income per share (in Shares)	27,604,006		27,826,586		28,050,638
Shares used in computing diluted income per share (in Shares)	28,008,960		28,306,732		28,609,619

[1] EPS in each quarter is computed using the weighted-average number of shares outstanding during that quarter while EPS for the full year is computed using the weighted-average number of shares outstanding during the year. Thus, the sum for the four quarters’ EPS does not necessarily equal the full year EPS