Goodwill And Intangible Assets (Schedule Of Goodwill) (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2020	Apr. 30, 2019	Apr. 30, 2018
Goodwill [Roll Forward]
Goodwill before impairment losses, beginning balance	$ 552,234	$ 540,168
Accumulated impairment losses, beginning balance	(32,297)	(32,297)
Goodwill, beginning balance	519,937	507,871
Other acquisitions		13,656
Disposals and foreign currency changes, net	(26,154)	(1,590)
Impairments	(106,000)	0	$ 0
Goodwill before impairment losses, ending balance	850,435	552,234	540,168
Accumulated impairment losses, ending balance	(138,297)	(32,297)	(32,297)
Goodwill, ending balance	712,138	$ 519,937	$ 507,871
Wave HQ Inc.
Goodwill [Roll Forward]
Other acquisitions	300,560
Goodwill, ending balance	300,560
Other acquisitions
Goodwill [Roll Forward]
Other acquisitions	$ 23,795