GOODWILL AND INTANGIBLE ASSETS (Schedule of Goodwill) (Details) - USD ($) $ in Thousands	3 Months Ended
	Jul. 31, 2020	Jul. 31, 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
Other acquisitions	0	1,083
Disposals and foreign currency changes, net	12,150	(3,101)
Impairments	0	0
Goodwill before impairment losses, ending balance	862,585	853,575
Accumulated impairment losses, ending balance	(138,297)	(32,297)
Goodwill, ending balance	$ 724,288	821,278
Wave
Goodwill [Roll Forward]
Other acquisitions		$ 303,359