Goodwill And Intangible Assets (Schedule Of Goodwill) (Details) - USD ($) $ in Thousands	9 Months Ended
	Jan. 31, 2019	Jan. 31, 2018
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	13,076	11,579
Disposals and foreign currency changes, net	(942)	2,003
Impairments	0	0
Goodwill before impairment losses, ending balance	552,302	537,086
Accumulated impairment losses, ending balance	(32,297)	(32,297)
Goodwill, ending balance	$ 520,005	$ 504,789