Consolidated Statements of Stockholders' Equity (USD $)	Common Stock [Member]	Additional Paid-in Capital [Member]	Common Stock Warrants [Member]	Treasury Stock [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Accumulated Deficit [Member]	Total
Balance at Apr. 30, 2010	$ 286,115	$ 268,038,251	$ 25,200,000	$ (18,528,989)	$ (63,797)	$ (164,071,933)	$ 110,859,647
Balance (shares) at Apr. 30, 2010	28,611,475
Common stock issued under stock-based compensation plans, net	11,005	21,575,794					21,586,799
Common stock issued under stock-based compensation plans, net (shares)	1,100,532
Purchase of Treasury Stock				(14,177,574)			(14,177,574)
Bond Hedge Valuation Allowance Release		10,966,456					10,966,456
Net income						46,725,710	46,725,710
Other comprehensive income (loss)					(507,688)		(507,688)
Balance at Apr. 29, 2011	297,120	300,580,501	25,200,000	(32,706,563)	(571,485)	(117,346,223)	175,453,350
Balance (shares) at Apr. 29, 2011	29,712,007
Common stock issued under stock-based compensation plans, net	9,266	21,380,385					21,389,651
Common stock issued under stock-based compensation plans, net (shares)	926,598
Purchase of Treasury Stock				(50,444,649)			(50,444,649)
Net income						36,077,732	36,077,732
Other comprehensive income (loss)					993,286		993,286
Balance at Apr. 27, 2012	306,386	321,960,886	25,200,000	(83,151,212)	421,801	(81,268,491)	183,469,370
Balance (shares) at Apr. 27, 2012	30,638,605						30,638,605
Common stock issued under stock-based compensation plans, net	6,498	24,282,446					24,288,944
Common stock issued under stock-based compensation plans, net (shares)	649,839
Tax benefits from stock-based compensation plans		12,361,561					12,361,561
Purchase of Treasury Stock				(33,009,673)			(33,009,673)
Common stock issued upon conversion of convertible notes	1	3,984					3,985
Common stock issued upon conversion of convertible notes (shares)	96
Warrants settlements		21,550,084	(25,200,000)	279			(3,649,637)
Net income						46,357,502	46,357,502
Other comprehensive income (loss)					(253,824)		(253,824)
Balance at Apr. 26, 2013	$ 312,885	$ 380,158,961		$ (116,160,606)	$ 167,977	$ (34,910,989)	$ 229,568,228
Balance (shares) at Apr. 26, 2013	31,288,540						31,288,540