Goodwill And Intangible Assets (Schedule Of Goodwill) (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2021	Apr. 30, 2020	Apr. 30, 2019
Goodwill [Roll Forward]
Goodwill before impairment losses, beginning balance	$ 850,435	$ 552,234
Accumulated impairment losses, beginning balance	(138,297)	(32,297)
Goodwill, beginning balance	712,138	519,937
Acquisitions		23,795
Disposals and foreign currency changes, net	38,573	(26,154)
Impairments	0	(106,000)	$ 0
Goodwill before impairment losses, ending balance	895,956	850,435	552,234
Accumulated impairment losses, ending balance	(138,297)	(138,297)	(32,297)
Goodwill, ending balance	757,659	712,138	$ 519,937
Wave HQ Inc.
Goodwill [Roll Forward]
Acquisitions		$ 300,560
Goodwill, ending balance	300,560
Acquisitions
Goodwill [Roll Forward]
Acquisitions	$ 6,948