Goodwill And Intangible Assets (Schedule Of Goodwill) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Jul. 31, 2011	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2011
Goodwill [Roll Forward]
Goodwill before impairment losses, beginning balance	$ 459,039	$ 459,863	$ 459,039
Accumulated impairment losses, beginning balance	(24,888)	(32,297)	(24,888)
Goodwill, beginning balance	434,151	427,566	434,151
Acquisitions		7,625	5,377
Disposals and foreign currency changes, net		(409)	(4,553)
Impairments	(99,700)	0	(7,409)	(22,700)
Goodwill before impairment losses, ending balance		467,079	459,863	459,039
Accumulated impairment losses, ending balance		(32,297)	(32,297)	(24,888)
Goodwill, ending balance		$ 434,782	$ 427,566	$ 434,151