Goodwill And Intangible Assets (Schedule Of Goodwill) (Details) - USD ($) $ in Thousands	3 Months Ended
	Jul. 31, 2015	Jul. 31, 2014
Goodwill [Roll Forward]
Goodwill before impairment losses, beginning balance	$ 474,128	$ 468,414
Accumulated impairment losses, beginning balance	(32,297)	(32,297)
Goodwill, beginning balance	441,831	436,117
Acquisitions	14,030	42,274
Disposals and foreign currency changes, net	1,467	(454)
Impairments	0	0
Goodwill before impairment losses, ending balance	486,691	511,142
Accumulated impairment losses, ending balance	(32,297)	(32,297)
Goodwill, ending balance	$ 454,394	$ 478,845