Goodwill And Intangible Assets (Schedule Of Intangible Assets) (Details) - USD ($) $ in Thousands	Oct. 31, 2017	Apr. 30, 2017	Oct. 31, 2016
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	$ 848,417	$ 812,133	$ 799,775
Accumulated Amortization	(441,977)	(402,769)	(366,640)
Net	406,440	409,364	433,135
Reacquired franchise rights
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	331,290	331,150	322,916
Accumulated Amortization	(101,987)	(90,877)	(79,484)
Net	229,303	240,273	243,432
Customer relationships
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	234,909	234,603	211,106
Accumulated Amortization	(147,881)	(133,207)	(117,539)
Net	87,028	101,396	93,567
Internally-developed software
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	146,985	139,709	137,533
Accumulated Amortization	(117,162)	(108,379)	(104,022)
Net	29,823	31,330	33,511
Noncompete agreements
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	32,471	32,408	31,625
Accumulated Amortization	(28,644)	(27,559)	(26,520)
Net	3,827	4,849	5,105
Franchise agreements
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	19,201	19,201	19,201
Accumulated Amortization	(11,414)	(10,774)	(10,134)
Net	7,787	8,427	9,067
Purchased technology
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	54,700	54,700	54,700
Accumulated Amortization	(34,889)	(31,973)	(28,941)
Net	19,811	22,727	25,759
Acquired assets pending final allocation
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	28,861	362	22,694
Accumulated Amortization	0	0	0
Net	$ 28,861	$ 362	$ 22,694