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		9 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2019	Jan. 31, 2018
Earnings Per Share [Abstract]
Net loss from continuing operations attributable to shareholders	$ (119,779)	$ (242,925)	$ (439,513)	$ (519,055)
Amounts allocated to participating securities	(160)	(177)	(446)	(498)
Net loss from continuing operations attributable to common shareholders	$ (119,939)	$ (243,102)	$ (439,959)	$ (519,553)
Basic weighted average common shares (in shares)	205,532	209,080	206,242	208,693
Potential dilutive shares (in shares)	0	0	0	0
Dilutive weighted average common shares (in shares)	205,532	209,080	206,242	208,693
Basic (in usd per share)	$ (0.58)	$ (1.16)	$ (2.13)	$ (2.49)
Diluted (in usd per share)	$ (0.58)	$ (1.16)	$ (2.13)	$ (2.49)