Goodwill and Intangible Assets (Schedule of Intangible Assets) (Details) - USD ($) $ in Thousands	Oct. 31, 2019	Apr. 30, 2019	Oct. 31, 2018
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	$ 994,523	$ 872,195	$ 869,264
Accumulated Amortization	(569,146)	(529,702)	(504,740)
Net	425,377	342,493	364,524
Reacquired franchise rights
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	355,116	350,410	339,719
Accumulated Amortization	(147,313)	(136,345)	(124,733)
Net	207,803	214,065	214,986
Customer relationships
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	299,245	274,838	256,739
Accumulated Amortization	(211,681)	(195,174)	(179,011)
Net	87,564	79,664	77,728
Internally-developed software
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	149,644	139,239	142,147
Accumulated Amortization	(113,863)	(109,885)	(117,060)
Net	35,781	29,354	25,087
Noncompete agreements
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	40,636	33,376	32,879
Accumulated Amortization	(32,620)	(31,446)	(30,596)
Net	8,016	1,930	2,283
Franchise agreements
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	19,201	19,201	19,201
Accumulated Amortization	(13,974)	(13,334)	(12,694)
Net	5,227	5,867	6,507
Purchased technology
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	122,700	54,700	54,700
Accumulated Amortization	(49,503)	(43,518)	(40,646)
Net	73,197	11,182	14,054
Trade name
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	5,800
Accumulated Amortization	(192)
Net	5,608
Acquired assets pending final allocation
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	2,181	431	23,879
Accumulated Amortization	0	0	0
Net	$ 2,181	$ 431	$ 23,879