GOODWILL AND INTANGIBLE ASSETS (Schedule of Intangible Assets) (Details) - USD ($) $ in Thousands	Oct. 31, 2020	Apr. 30, 2020	Oct. 31, 2019
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,031,647	$ 1,022,157	$ 994,523
Accumulated Amortization	(641,276)	(607,181)	(569,146)
Net	390,371	414,976	425,377
Reacquired franchise rights
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	367,151	365,062	355,116
Accumulated Amortization	(169,613)	(159,754)	(147,313)
Net	197,538	205,308	207,803
Customer relationships
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	311,291	314,191	299,245
Accumulated Amortization	(237,906)	(227,445)	(211,681)
Net	73,385	86,746	87,564
Internally-developed software
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	164,610	154,083	149,644
Accumulated Amortization	(118,216)	(113,698)	(113,863)
Net	46,394	40,385	35,781
Noncompete agreements
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	40,894	41,072	40,636
Accumulated Amortization	(34,436)	(33,639)	(32,620)
Net	6,458	7,433	8,016
Franchise agreements
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	19,201	19,201	19,201
Accumulated Amortization	(15,254)	(14,614)	(13,974)
Net	3,947	4,587	5,227
Purchased technology
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	122,700	122,700	122,700
Accumulated Amortization	(65,078)	(57,548)	(49,503)
Net	57,622	65,152	73,197
Trade name
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	5,800	5,800	5,800
Accumulated Amortization	(773)	(483)	(192)
Net	$ 5,027	5,317	5,608
Acquired assets pending final allocation
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount		48	2,181
Accumulated Amortization		0	0
Net		$ 48	$ 2,181