Stockholders' Equity (Details) (USD $) In Thousands, except Share data	6 Months Ended	12 Months Ended
	Oct. 27, 2008	Apr. 30, 2011	Apr. 30, 2010	Apr. 30, 2009
Stock repurchased and retired during period shares		19,000,000	12,800,000
Stock repurchased and retired during period value		$ 279,947	$ 250,003
Common stock sold	8,300,000
Price per share	$ 17.50
Proceeds from issuance of common stock, net	$ 141,400			$ 141,415
Preferred stock		500,000	500,000
Authorized unissued preferred stock		5,600,000
Convertible Preferred Stock [Member]
Preferred stock		500,000
Preferred Stock No Par Value [Member]
Preferred stock		6,000,000
Participating Preferred Stock [Member]
Authorized unissued preferred stock		600,000