Loss Per Share And Stockholders' Equity (Allocation Of Cost Of Shares Retired To Components Of Stockholders' Equity) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Oct. 31, 2012	Oct. 31, 2011
Earnings Per Share And Equity [Line Items]
Cost of common shares retired	$ 315,000	$ 177,500
Cost of treasury shares retired	1,140,797
Net impact on consolidated stockholders' equity
Common Stock [Member]
Earnings Per Share And Equity [Line Items]
Cost of common shares retired	213
Cost of treasury shares retired	600
Additional Paid-in Capital [Member]
Earnings Per Share And Equity [Line Items]
Cost of common shares retired	12,542
Cost of treasury shares retired	35,400
Retained Earnings [Member]
Earnings Per Share And Equity [Line Items]
Cost of common shares retired	302,245
Cost of treasury shares retired	$ 1,104,797