Goodwill And Intangible Assets (Schedule Of Intangible Assets) (Details) - USD ($) $ in Thousands	Jul. 31, 2018	Apr. 30, 2018	Jul. 31, 2017
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	$ 842,109	$ 843,073	$ 817,028
Accumulated Amortization	(487,278)	(469,092)	(423,056)
Net	354,831	373,981	393,972
Reacquired franchise rights
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	339,747	339,779	331,371
Accumulated Amortization	(119,386)	(113,856)	(96,600)
Net	220,361	225,923	234,771
Customer relationships
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	256,858	256,137	235,413
Accumulated Amortization	(171,542)	(164,005)	(140,881)
Net	85,316	92,132	94,532
Internally-developed software
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	137,914	140,255	143,206
Accumulated Amortization	(114,622)	(111,734)	(112,894)
Net	23,292	28,521	30,312
Noncompete agreements
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	32,888	32,899	32,498
Accumulated Amortization	(30,144)	(29,673)	(28,143)
Net	2,744	3,226	4,355
Franchise agreements
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	19,201	19,201	19,201
Accumulated Amortization	(12,374)	(12,054)	(11,094)
Net	6,827	7,147	8,107
Purchased technology
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	54,700	54,700	54,700
Accumulated Amortization	(39,210)	(37,770)	(33,444)
Net	15,490	16,930	21,256
Acquired assets pending final allocation
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	801	102	639
Accumulated Amortization	0	0	0
Net	$ 801	$ 102	$ 639