GOODWILL AND INTANGIBLE ASSETS (Schedule of Goodwill) (Details) - USD ($) $ in Thousands	9 Months Ended
	Jan. 31, 2020	Jan. 31, 2019
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
Acquisitions	23,421	13,076
Disposals and foreign currency changes, net	(5,088)	(942)
Impairments	0	0
Goodwill before impairment losses, ending balance	871,127	552,302
Accumulated impairment losses, ending balance	(32,297)	(32,297)
Goodwill, ending balance	838,830	$ 520,005
Wave
Goodwill [Roll Forward]
Acquisitions	$ 300,560