Goodwill And Intangible Assets (Schedule Of Goodwill) (Details) - USD ($) $ in Thousands	9 Months Ended
	Jan. 31, 2017	Jan. 31, 2016
Goodwill [Roll Forward]
Goodwill before impairment losses, beginning balance	$ 503,054	$ 474,128
Accumulated impairment losses, beginning balance	(32,297)	(32,297)
Goodwill, beginning balance	470,757	441,831
Acquisitions	13,346	4,025
Disposals and foreign currency changes, net	(783)	(2,438)
Impairments	0	0
Goodwill before impairment losses, ending balance	515,617	475,715
Accumulated impairment losses, ending balance	(32,297)	(32,297)
Goodwill, ending balance	$ 483,320	$ 443,418