Goodwill And Intangible Assets (Schedule Of Goodwill) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2012
Goodwill [Roll Forward]
Goodwill before impairment losses, beginning balance	$ 467,079	$ 459,863
Accumulated impairment losses, beginning balance	(32,297)	(32,297)
Goodwill, beginning balance	434,782	427,566
Acquisitions	3,086	7,625
Disposals and foreign currency changes, net	(1,751)	(409)
Impairments	0	0	(7,409)
Goodwill before impairment losses, ending balance	468,414	467,079	459,863
Accumulated impairment losses, ending balance	(32,297)	(32,297)	(32,297)
Goodwill, ending balance	$ 436,117	$ 434,782	$ 427,566