Goodwill And Intangible Assets (Schedule Of Goodwill) (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2016	Apr. 30, 2015
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	27,765	7,628
Disposals and foreign currency changes, net	(1,161)	(1,914)
Impairments	0	0
Goodwill before impairment losses, ending balance	503,054	474,128
Accumulated impairment losses, ending balance	(32,297)	(32,297)
Goodwill, ending balance	$ 470,757	$ 441,831