Loss Per Share and Stockholders' Equity (Details) (USD $)	3 Months Ended		9 Months Ended
	Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2014	Jan. 31, 2013
Earnings Per Share [Abstract]
Net loss from continuing operations attributable to shareholders	$ (212,751,000)	$ (16,915,000)	$ (429,036,000)	$ (223,764,000)
Amounts allocated to participating securities	(88,000)	(62,000)	(242,000)	(199,000)
Net loss from continuing operations attributable to common shareholders	(212,839,000)	(16,977,000)	(429,278,000)	(223,963,000)
Basic weighted average common shares (in shares)	274,110,000	271,542,000	273,699,000	273,281,000
Potential dilutive shares (in shares)	0	0	0	0
Weighted Average Number of Shares Outstanding, Diluted	274,110,000	271,542,000	273,699,000	273,281,000
Basic (in usd per share)	$ (0.78)	$ (0.06)	$ (1.57)	$ (0.82)
Narrative Details [Abstract]
Antidilutive securities excluded from computation of earnings per share, amount (in shares)			5,700,000	7,700,000
Shares repurchased and retired (in shares)				21,300,000
Share repurchase and retired, value			315,000,000
Shares repurchased during the period, (in shares)			200,000	200,000
Shares repurchased during the period, Value			6,000,000	2,800,000
Shares issued during period (in shares)			1,800,000	1,300,000
Nonvested units granted			900,000
Stock-based compensation	4,700,000	3,700,000	15,500,000	11,500,000
Unrecognized compensation costs, options	1,400,000		1,400,000
Unrecognized compensation costs, nonvested shares and units	$ 28,200,000		$ 28,200,000