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
	Jul. 31, 2018	Jul. 31, 2017
Earnings Per Share [Abstract]
Net loss from continuing operations attributable to shareholders	$ (148,797)	$ (127,818)
Amounts allocated to participating securities	(142)	(160)
Net loss from continuing operations attributable to common shareholders	$ (148,939)	$ (127,978)
Basic weighted average common shares (in shares)	207,673	207,935
Potential dilutive shares (in shares)	0	0
Dilutive weighted average common shares (in shares)	207,673	207,935
Basic (in usd per share)	$ (0.72)	$ (0.62)
Diluted (in usd per share)	$ (0.72)	$ (0.62)