Goodwill And Intangible Assets (Schedule Of Intangible Assets) (Details) - USD ($) $ in Thousands	Jan. 31, 2019	Apr. 30, 2018	Jan. 31, 2018
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	$ 880,450	$ 843,073	$ 855,857
Accumulated Amortization	(523,498)	(469,092)	(464,864)
Net	356,952	373,981	390,993
Reacquired franchise rights
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	350,459	339,779	339,544
Accumulated Amortization	(130,618)	(113,856)	(108,063)
Net	219,841	225,923	231,481
Customer relationships
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	274,293	256,137	251,792
Accumulated Amortization	(187,080)	(164,005)	(156,234)
Net	87,213	92,132	95,558
Internally-developed software
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	147,465	140,255	151,095
Accumulated Amortization	(119,664)	(111,734)	(123,309)
Net	27,801	28,521	27,786
Noncompete agreements
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	33,369	32,899	32,853
Accumulated Amortization	(31,040)	(29,673)	(29,195)
Net	2,329	3,226	3,658
Franchise agreements
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	19,201	19,201	19,201
Accumulated Amortization	(13,014)	(12,054)	(11,734)
Net	6,187	7,147	7,467
Purchased technology
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	54,700	54,700	54,700
Accumulated Amortization	(42,082)	(37,770)	(36,329)
Net	12,618	16,930	18,371
Acquired assets pending final allocation
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	963	102	6,672
Accumulated Amortization	0	0	0
Net	$ 963	$ 102	$ 6,672