Goodwill And Intangible Assets (Schedule Of Intangible Assets) (Details) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2013	Apr. 30, 2012
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	$ 381,281	$ 362,301
Accumulated Amortization	(109,758)	(97,850)
Net	271,523	264,451
Reacquired Franchise Rights [Member]
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	214,330	214,330
Accumulated Amortization	(17,174)	(14,083)
Net	197,156	200,247
Customer Relationships [Member]
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	108,596	90,433
Accumulated Amortization	(52,820)	(46,504)
Net	55,776	43,929
Noncompete Agreements [Member]
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	23,054	22,337
Accumulated Amortization	(21,627)	(21,425)
Net	1,427	912
Franchise Agreements [Member]
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	19,201	19,201
Accumulated Amortization	(5,334)	(4,373)
Net	13,867	14,828
Purchased Technology [Member]
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	14,800	14,700
Accumulated Amortization	(11,911)	(10,665)
Net	2,889	4,035
Trade Name [Member]
Goodwill and Intangible Assets [Line Items]
Gross Carrying Amount	1,300	1,300
Accumulated Amortization	(892)	(800)
Net	$ 408	$ 500