Goodwill And Intangible Assets (Schedule Of Intangible Assets) (Details) - USD ($) $ in Thousands	Jan. 31, 2018	Apr. 30, 2017	Jan. 31, 2017
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	$ 855,857	$ 812,133	$ 820,609
Accumulated Amortization	(464,864)	(402,769)	(385,889)
Net	390,993	409,364	434,720
Reacquired franchise rights
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	339,544	331,150	328,321
Accumulated Amortization	(108,063)	(90,877)	(85,127)
Net	231,481	240,273	243,194
Customer relationships
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	251,792	234,603	216,449
Accumulated Amortization	(156,234)	(133,207)	(124,771)
Net	95,558	101,396	91,678
Internally-developed software
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	151,095	139,709	142,571
Accumulated Amortization	(123,309)	(108,379)	(108,047)
Net	27,786	31,330	34,524
Noncompete agreements
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	32,853	32,408	31,821
Accumulated Amortization	(29,195)	(27,559)	(27,033)
Net	3,658	4,849	4,788
Franchise agreements
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	19,201	19,201	19,201
Accumulated Amortization	(11,734)	(10,774)	(10,454)
Net	7,467	8,427	8,747
Purchased technology
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	54,700	54,700	54,700
Accumulated Amortization	(36,329)	(31,973)	(30,457)
Net	18,371	22,727	24,243
Acquired assets pending final allocation
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	6,672	362	27,546
Accumulated Amortization	0	0	0
Net	$ 6,672	$ 362	$ 27,546