Goodwill And Intangible Assets (Schedule Of Goodwill) (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Jan. 31, 2015	Jan. 31, 2014
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	9,614	5,206
Disposals and foreign currency changes, net	(2,770)	(2,602)
Impairments	0	0
Goodwill before impairment losses, ending balance	475,258	469,683
Accumulated impairment losses, ending balance	(32,297)	(32,297)
Goodwill, ending balance	$ 442,961	$ 437,386