Goodwill And Intangible Assets (Schedule Of Intangible Assets) (Details) - USD ($) $ in Thousands	Apr. 30, 2020	Apr. 30, 2019
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	$ 1,022,157	$ 872,195
Accumulated Amortization	(607,181)	(529,702)
Net	414,976	342,493
Reacquired franchise rights
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	365,062	350,410
Accumulated Amortization	(159,754)	(136,345)
Net	205,308	214,065
Customer relationships
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	314,191	274,838
Accumulated Amortization	(227,445)	(195,174)
Net	86,746	79,664
Internally-developed software
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	154,083	139,239
Accumulated Amortization	(113,698)	(109,885)
Net	40,385	29,354
Noncompete agreements
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	41,072	33,376
Accumulated Amortization	(33,639)	(31,446)
Net	7,433	1,930
Franchise agreements
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	19,201	19,201
Accumulated Amortization	(14,614)	(13,334)
Net	4,587	5,867
Purchased technology
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	122,700	54,700
Accumulated Amortization	(57,548)	(43,518)
Net	65,152	11,182
Trade name
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	5,800	0
Accumulated Amortization	(483)	0
Net	5,317	0
Acquired assets pending final allocation
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	48	431
Accumulated Amortization	0	0
Net	$ 48	$ 431