Goodwill And Intangible Assets (Schedule Of Goodwill) (Details) - USD ($) $ in Thousands	9 Months Ended
	Jan. 31, 2016	Jan. 31, 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	4,025	9,614
Disposals and foreign currency changes, net	2,438	2,770
Impairments	0	0
Goodwill before impairment losses, ending balance	475,715	475,258
Accumulated impairment losses, ending balance	(32,297)	(32,297)
Goodwill, ending balance	$ 443,418	$ 442,961