Goodwill And Intangible Assets (Schedule Of Goodwill) (Details) - USD ($) $ in Thousands	6 Months Ended
	Oct. 31, 2015	Oct. 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	1,852	28,378
Disposals and foreign currency changes, net	1,615	313
Impairments	0	0
Goodwill before impairment losses, ending balance	474,365	496,479
Accumulated impairment losses, ending balance	(32,297)	(32,297)
Goodwill, ending balance	$ 442,068	$ 464,182