Goodwill And Intangible Assets (Schedule Of Goodwill) (Details) - USD ($) $ in Thousands	6 Months Ended
	Oct. 31, 2018	Oct. 31, 2017
Goodwill [Roll Forward]
Goodwill before impairment losses, beginning balance	$ 540,168	$ 523,504
Accumulated impairment losses, beginning balance	(32,297)	(32,297)
Goodwill, beginning balance	507,871	491,207
Acquisitions	624	961
Disposals and foreign currency changes, net	(1,304)	891
Impairments	0	0
Goodwill before impairment losses, ending balance	539,488	525,356
Accumulated impairment losses, ending balance	(32,297)	(32,297)
Goodwill, ending balance	$ 507,191	$ 493,059