Goodwill And Intangible Assets (Schedule Of Goodwill) (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Oct. 31, 2014	Oct. 31, 2013
Goodwill [Roll Forward]
Goodwill before impairment losses, beginning balance	$ 468,414	$ 467,079
Accumulated impairment losses, beginning balance	(32,297)	(32,297)
Goodwill, beginning balance	436,117	434,782
Acquisitions	28,378	9,207
Disposals and foreign currency changes, net	(313)	(1,177)
Impairments	0	0
Goodwill before impairment losses, ending balance	496,479	475,109
Accumulated impairment losses, ending balance	(32,297)	(32,297)
Goodwill, ending balance	$ 464,182	$ 442,812