Goodwill And Intangible Assets (Schedule Of Intangible Assets) (Details) - USD ($) $ in Thousands	Apr. 30, 2021	Apr. 30, 2020
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,031,841	$ 1,022,157
Accumulated Amortization	(671,693)	(607,181)
Net	360,148	414,976
Reacquired franchise rights
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	370,112	365,062
Accumulated Amortization	(179,356)	(159,754)
Net	190,756	205,308
Customer relationships
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	316,508	314,191
Accumulated Amortization	(251,160)	(227,445)
Net	65,348	86,746
Internally-developed software
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	156,308	154,083
Accumulated Amortization	(116,126)	(113,698)
Net	40,182	40,385
Noncompete agreements
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	41,212	41,072
Accumulated Amortization	(35,484)	(33,639)
Net	5,728	7,433
Franchise agreements
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	19,201	19,201
Accumulated Amortization	(15,894)	(14,614)
Net	3,307	4,587
Purchased technology
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	122,700	122,700
Accumulated Amortization	(72,609)	(57,548)
Net	50,091	65,152
Trade name
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	5,800	5,800
Accumulated Amortization	(1,064)	(483)
Net	4,736	5,317
Acquired assets pending final allocation
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	0	48
Accumulated Amortization	0	0
Net	$ 0	$ 48