GOODWILL AND INTANGIBLE ASSETS (Schedule of Intangible Assets) (Details) - USD ($) $ in Thousands	Jan. 31, 2021	Apr. 30, 2020	Jan. 31, 2020
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,044,196	$ 1,022,157	$ 1,023,821
Accumulated Amortization	(662,932)	(607,181)	(590,747)
Net	381,264	414,976	433,074
Reacquired franchise rights
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	370,076	365,062	364,376
Accumulated Amortization	(174,484)	(159,754)	(153,392)
Net	195,592	205,308	210,984
Customer relationships
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	316,600	314,191	313,521
Accumulated Amortization	(244,441)	(227,445)	(219,664)
Net	72,159	86,746	93,857
Internally-developed software
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	168,642	154,083	154,962
Accumulated Amortization	(123,709)	(113,698)	(116,383)
Net	44,933	40,385	38,579
Noncompete agreements
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	41,177	41,072	41,386
Accumulated Amortization	(34,962)	(33,639)	(33,151)
Net	6,215	7,433	8,235
Franchise agreements
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	19,201	19,201	19,201
Accumulated Amortization	(15,574)	(14,614)	(14,294)
Net	3,627	4,587	4,907
Purchased technology
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	122,700	122,700	122,801
Accumulated Amortization	(68,844)	(57,548)	(53,525)
Net	53,856	65,152	69,276
Trade name
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	5,800	5,800	5,800
Accumulated Amortization	(918)	(483)	(338)
Net	$ 4,882	5,317	5,462
Acquired assets pending final allocation
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount		48	1,774
Accumulated Amortization		0	0
Net		$ 48	$ 1,774