Goodwill And Intangible Assets (Schedule Of Goodwill) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Jan. 31, 2014	Jan. 31, 2013
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	5,206	7,650
Disposals and foreign currency changes, net	(2,602)	40
Impairments	0	0
Goodwill before impairment losses, ending balance	469,683	467,553
Accumulated impairment losses, ending balance	(32,297)	(32,297)
Goodwill, ending balance	$ 437,386	$ 435,256