Loss Per Share and Stockholders' Equity (Computations of Basic and Diluted Earnings Per Share) (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Oct. 31, 2019	Oct. 31, 2018	Oct. 31, 2019	Oct. 31, 2018
Earnings Per Share [Abstract]
Net loss from continuing operations attributable to shareholders	$ (183,554)	$ (170,937)	$ (329,278)	$ (319,734)
Amounts allocated to participating securities	(150)	(144)	(299)	(286)
Net loss from continuing operations attributable to common shareholders	$ (183,704)	$ (171,081)	$ (329,577)	$ (320,020)
Basic weighted average common shares (in shares)	198,079	205,520	200,058	206,596
Potential dilutive shares (in shares)	0	0	0	0
Dilutive weighted average common shares (in shares)	198,079	205,520	200,058	206,596
Basic (in usd per share)	$ (0.93)	$ (0.83)	$ (1.65)	$ (1.55)
Diluted (in usd per share)	$ (0.93)	$ (0.83)	$ (1.65)	$ (1.55)